# data[].attributes.body
Yeah, you all know who this fine fellow is. After all, they were all over the news at one point due to a certain infamous documentary (but we'll talk about that later). For now, let's focus on what else we know about our beloved killer whales.

# data[].attributes.body
Fun fact: Orcas are actually in the same family as dolphins!

# data[].attributes.body
Recent research suggests that Orcinus orca may in fact be a species complex! Several distinct "ecotypes" have been discovered, each with their own specific behaviors, diets, and ranges.

Source: Morin PA, Archer FI, Foote AD, Vilstrup J, Allen EE, Wade P, Durban J, Parsons K, Pitman R, Li L, et al. 2010. Complete mitochondrial genome phylogeographic analysis of killer whales (Orcinus orca) indicates multiple species. Genome Research 20: 908–916.

# data[].attributes.attachment_link.readable_text
Abstract

Killer whales ( Orcinus orca) currently comprise a single, cosmopolitan species with a diverse diet. However, studies over the last 30 yr have revealed populations of sympatric "ecotypes" with discrete prey preferences, morphology, and behaviors. Although these ecotypes avoid social interactions and are not known to interbreed, genetic studies to date have found extremely low levels of diversity in the mitochondrial control region, and few clear phylogeographic patterns worldwide. This low level of diversity is likely due to low mitochondrial mutation rates that are common to cetaceans. Using killer whales as a case study, we have developed a method to readily sequence, assemble, and analyze complete mitochondrial genomes from large numbers of samples to more accurately assess phylogeography and estimate divergence times. This represents an important tool for wildlife management, not only for killer whales but for many marine taxa. We used high-throughput sequencing to survey whole mitochondrial genome variation of 139 samples from the North Pacific, North Atlantic, and southern oceans. Phylogenetic analysis indicated that each of the known ecotypes represents a strongly supported clade with divergence times ranging from ∼150,000 to 700,000 yr ago. We recommend that three named ecotypes be elevated to full species, and that the remaining types be recognized as subspecies pending additional data. Establishing appropriate taxonomic designations will greatly aid in understanding the ecological impacts and conservation needs of these important marine predators. We predict that phylogeographic mitogenomics will become an important tool for improved statistical phylogeography and more precise estimates of divergence times.

Theory and empirical studies have shown ecology to be a driving force in speciation ( Schluter 2009). Ancestral populations can subdivide and radiate into novel ecological niches and are then subject to divergent selection and subsequent adaptive divergence, which can lead to reproductive isolation and speciation ( Gavrilets and Losos 2009; Schluter 2009). This process of radiation into novel and divergent ecological niches is often characterized by a rapid burst of phenotypic diversification, which then slows as disparate ecological niches become filled ( Gavrilets and Losos 2009), and is consistent with phylogenies showing the greatest ecological differences early in a clade's history ( Grant and Grant 2008; Losos 2009).

Maintaining high levels of biodiversity by conserving both this process and the resultant genetic and phenotypic variation is an important goal of management bodies ( Moritz 2002). Determining units on divergent evolutionary trajectories can facilitate this, and a number of criteria and concepts have been suggested for defining species, subspecies, or management units. Some concepts are based purely upon genetic criteria such as reciprocal monophyly of mitochondrial DNA (mtDNA) haplotypes and significant divergence of allele frequencies at nuclear loci (e.g., Moritz 1994); others incorporate ecological and phenotypic data to assess "exchangeability" between putative species (e.g., Crandall et al. 2000; De Queiroz 2007). De Queiroz (2007) argued that the many concepts all agree in the basic description of species as independently evolving metapopulations, and that the criteria for defining these species all boil down to different types of supporting evidence.

Phylogenetic analysis using mtDNA is a widely used tool for the genetic component of delineating species ( Moritz 1994). The generally rapid rate of mtDNA sequence evolution and lineage sorting (relative to the nuclear genome) facilitate inference of evolutionary patterns ( Brown et al. 1982; Avise 1989; Moore 1995), especially for social species with a matrilineal group structure, which is common among terrestrial and oceanic mammals (e.g., Lyrholm and Gyllensten 1998; Nyakaana and Arctander 1999; Okello et al. 2008). Despite the general assumptions and its wide use, however, mtDNA sequence can in some cases be an uninformative marker for phylogenetics and species delineation if only portions of the genome are used ( Galtier et al. 2009b). Indeed, the mitochondrial "molecular clock" varies widely and has been shown to be especially slow in some taxa, e.g., cetaceans and sharks ( Nabholz et al. 2008a, b, 2009; Galtier et al. 2009a). Short sections of the mtDNA genome can therefore be uninformative phylogeographic markers in these taxa (e.g., Hoelzel et al. 2002). A further limitation of traditional mtDNA sequencing that focused on either the control region or cytochrome b sequences has been the inability to resolve relationships when a radiation was very rapid. Greater resolution of phylogenies can be achieved by increasing the amount of sequence data ( Saitou and Nei 1986; Ruvolo et al. 1991; Cummings et al. 1995; DeFilippis and Moore 2000; Rokas and Carroll 2005).

The advent of highly parallel long-read pyrosequencing technologies with targeted resequencing of large genetic regions from genetically tagged and pooled samples now makes it possible to rapidly and efficiently obtain orders-of-magnitude more sequence data than was previously possible with Sanger sequencing ( Meyer et al. 2008). Although whole mitochondrial genomes (mitogenomes) are now available for a number of species, they have typically been generated for deep phylogenetic analysis, and to allow more precise estimates of long divergence times ( Arnason et al. 2004, 2008; Xiong et al. 2009). To date, only a few studies have made use of phylogeographic mitogenomics to investigate patterns within a genus or species, and most have involved the use of few genomes, typically from species of medical or economic interest (e.g., Zarowiecki et al. 2007; Carr and Marshall 2008; Torriani et al. 2008). The ability to cost-effectively sequence the entire mitochondrial genome from larger numbers of samples for phylogeographic studies should help to resolve previously intractable polytomies resulting from low levels of sequence divergence or rapid radiations of many more species.

As a case study to investigate the potential of using whole mitochondrial genomes for phylogeography, we have undertaken a study of one such "difficult" species. Killer whales ( Orcinus orca) are apex predators found in all the world's oceans ( Forney and Wade 2006). Currently considered a single species ( Rice 1998), local variation in a number of characteristics, including body size, color patterning, social structure, vocalization pattern, and behavior, has led to the recognition of several named killer whale types (often referred to as "ecotypes") ( Barrett-Lennard et al. 1996; Ford et al. 1998; Baird 2000; Pitman and Ensor 2003; Deecke et al. 2005; Pitman et al. 2007; Foote et al. 2009; Parsons et al. 2009). In particular, prey specialization appears to be a defining characteristic of these types, with partially or fully sympatric populations having specific, sometimes nonoverlapping prey preferences (e.g., fish vs. marine mammals) ( Ford et al. 1998; Saulitis et al. 2000; Pitman and Ensor 2003; Herman et al. 2005; Krahn et al. 2007b). Although ecological specialization is not uncommon ( Gavrilets and Losos 2009; Schluter 2009), the fact that killer whales exhibit specialization within an ecosystem that is largely based on social mechanisms is of great interest, suggesting that speciation may have occurred in the absence of physical barriers to gene flow. Many killer whale populations are being negatively impacted by human activities, such as over-fishing and pollution, and such threats are likely to vary substantially between types (e.g., Ross et al. 2000; Ylitalo et al. 2001). Effective management therefore requires the delineation of conservation units ( Moritz 1994) within the genus Orcinus to facilitate different management strategies.

Despite a worldwide distribution and phenotypic differences among killer whale types, genetic diversity of mtDNA is low, and the control region and other mtDNA loci have been used with limited success to determine population structure and phylogeography. In a survey of ∼1000 bp of the control region from over 100 samples from various locations around the world, Hoelzel et al. (2002) found only 13 haplotypes and no clear pattern of genetic association with ocean basin or type. They concluded that killer whales had gone through a worldwide bottleneck ∼145,000-210,000 yr ago (i.e., during the Pleistocene), and that the genetic patterns reflected stochastic distribution of mitochondrial haplotypes following the post-bottleneck expansion, rather than phylogenetic lineages reflecting the evolution of ecotypes. Analysis of an expanded set of mtDNA control region sequences by LeDuc et al. (2008), including 80 samples from three described types in the Southern Ocean around Antarctica, found similar patterns, but also found that two Antarctic types associated with the ice edge were each monophyletic, albeit with very low levels of differentiation. Indeed, levels of differentiation among types worldwide have been marked by only one to six fixed differences and total genetic distances of <0.3% for the most divergent control region lineages. This low level of mtDNA diversity has resulted in only weak inference of phylogeographic patterns and divergence times in killer whales, limiting our ability to understand their evolution and taxonomy. Studies of nuclear microsatellites have begun to clarify population structure within ecotypes, and propose even more recent divergence of regional ecotypes within the last 20,000-40,000 yr ( Hoelzel et al. 2007; Pilot et al. 2010).

Killer whales are therefore an ideal candidate species for applying new high-throughput sequencing techniques to allow the production of a highly corroborated mitogenome tree and the testing of hypotheses of the timing of coalescence of killer whale populations (e.g., Hoelzel et al. 2002), with a precision of temporal discrimination not previously possible. Specifically, we test the hypotheses that killer whale ecotypes radiated toward the end of the Pleistocene, that ecotypes diversified regionally within ocean basins, and that mitochondrial haplotypes are stochastically distributed among ecotypes.

Results

Full-length mitochondrial genomes of ∼16,390 bp (16,386-16,392 bp) were sequenced and assembled for 143 killer whale samples ( Fig. 1) and three other cetacean species (false killer whale Pseudorca crassidens and long- and short-finned pilot whales Globicephala macrorhynchus, G. melas) for use as outgroups. An additional five partial mitochondrial sequences were generated, with one or more gaps in the sequence ranging from 35 bp to ∼9 kb. Analysis of eight full mitochondrial sequences that were replicated yielded only two differences (not including polynucleotide repeats), for a sequence error rate of ∼0.00076%. These included one sample sequenced in separate U.S. and Danish sequencing facilities as well as intra-lab replication. Mutation rate estimates for the whole mitogenome were 2.6 × 10 −3 (1.50-3.83 × 10 −3) substitutions per site per million years for Orcinus. This rate is lower than the mean for mammals (3.3 × 10 −2), and similar to rates estimated for other cetaceans (2.3 × 10 −3, extrapolated from third positions only) ( Nabholz et al. 2008a).

Previously published mitogenome sequences were combined with sequences generated in this study to estimate the time of divergence for the genus Orcinus ( Fig. 2A). Within Orcinus, 139 mitogenomes (66 distinct haplotypes) were used for further analysis, after removal of duplicates and one poor-quality sequence. Bayesian analysis of the 66 unique haplotypes produced the phylogenetic tree shown in Figure 2B. In contrast to results based on the control region sequences alone ( Hoelzel et al. 2002; LeDuc et al. 2008), no haplotypes were shared between killer whale types or ocean basins. However, animals of unknown type from multiple oceanic regions were grouped in the phylogenetic tree with the Offshore, eastern North Atlantic (ENA) Type 1, Antarctic Type A, and Transient types ( Fig. 2B), indicating possible common ancestry of widely separated populations, or, in the case of the one putative Antarctic A type that clusters with eastern North Pacific (ENP) Transient type (predominantly coastal mammal-eating specialist; Ford and Ellis 1999; Baird 2000), potentially an as yet undescribed new killer whale type in the Southern Ocean.

The most striking feature of the phylogenetic tree is the relatively deep divergence of the ENP Transient clade from all others, including two sympatric groups, the Offshore and Resident types. The estimated divergence time is 700,000 yr ago (95% highest posterior density interval [HPDI] = 488,000-960,000), and this clade has 40 fixed differences from all other samples when the single Type A sample is excluded (36 when included). This is 17% of all of the variable sites detected genus-wide. All other types differ from each other by three to 25 fixed differences ( Table 1). The time to most recent common ancestor (TMRCA) within Transients is estimated at ∼190,000 yr ago, and other types have mean TMRCAs ranging from 59,000 to 117,000 yr ago ( Table 2). The Antarctic types (including the single sample from the Gulf of Mexico) together form a clade with a mean TMRCA of ∼330,000 yr.

The "Resident" clade includes all fish-eating, coastal Resident types ( Baird 2000). The "Offshore" clade includes all ENP Offshore types (a relatively little known type thought to specialize on bony fish and elasmobranchs; Baird 2000; Dahlheim et al. 2008) and other Pacific Ocean samples from off western Mexico and Clipperton Island that were not previously identified as part of the Offshore population. Interestingly, one sample from Newfoundland (western North Atlantic; WNA) also clusters with the ENP Offshore haplotypes, indicating either an origin of the ENP Offshore and Resident groups from ancestral populations in the North Atlantic, or a remigration of animals in the ENP to the WNA via the Northwest Passage during periods of climate warming.

The "ENA 1-2" clade contains two haplotypes that diverged at approximately the same time as the ENP Offshore and Resident clades. These are from animals sampled near Iceland, Scotland, and England. The Icelandic and English samples were previously categorized as a generalist type (North Atlantic Type 1) that includes individuals specializing on fish and individuals that are thought to predate both fish and mammals ( Foote et al. 2009). The Scottish sample was categorized as being from a poorly characterized North Atlantic specialist type (Type 2) and had previously been clustered with Antarctic killer whales based on control region data ( Foote et al. 2009). ENA type 2 killer whales were represented by only a single sample, and the sequence contained a large gap (3848 bp). This type has been characterized primarily using museum specimens ( Foote et al. 2009), not suitable for long-range PCR. Sequencing methods used to obtain ancient mitogenome sequences (see Ho and Gilbert 2010) may be more suitable for further investigating the phylogenetic relationship between types within the ENA.

The "ENA Type 1" clade clusters a sample from New Zealand with whales from Iceland, Norway, and the Strait of Gibraltar. ENA type 1 has recently been described based on diet and morphology ( Foote et al. 2009). Together, the ENA samples cluster closely to the ENP Resident and Offshore types. Samples from both ocean basins appear to have similar levels of haplotypic diversity, so it is unclear whether the ancestral population was in the North Atlantic or the North Pacific, or if both arose from a broader generalist population in lower latitudes that is not yet adequately sampled.

There are three described Antarctic types that differ in diet and morphology ( Pitman and Ensor 2003; Pitman et al. 2007). All Antarctic samples except one (AntA2) cluster in a monophyletic group that also includes one sample from the Gulf of Mexico in the WNA, and this group is more closely related to all other types in both the ENA and ENP than to the ENP Transients. Two of the three types (B and C) in the Antarctic are also monophyletic, with three fixed differences between types B and C and 24-25 fixed differences between type A (excluding AntA2) and types B and C, respectively. The single sample from the Southern Ocean that does not cluster with the Antarctic types clusters basal to the Transient-type samples, indicating that it may in fact represent a separate population of Transient-like whales in the southern hemisphere. Further sampling in this region is warranted, especially in light of recent observations of a possible fourth pelagic killer whale type in the southern oceans ( Jefferson et al. 2007).

Mitochondrial DNA, though useful in phylogeographic studies, has the limitation of being a single, maternally inherited locus. Nuclear markers are needed to obtain data from multiple loci and from both male and female genetic components. Although microsatellites are a poor marker for taxonomic questions, they are the marker of choice for many intraspecific studies, and have been used to study killer whale types. In the North Pacific, previous analysis of 16 nuclear microsatellites has shown that types are genetically very distinct ( Hoelzel et al. 2007). Our data from 26 microsatellites genotyped from samples in the North Pacific and Antarctic indicate similarly high levels of differentiation among all killer whale types ( Table 3), when divergence is calculated as Hedrick's G′ ST to control for intrapopulation levels of diversity ( Hedrick 2005). These data are somewhat preliminary due to small sample sizes for three of the killer whale types and no data from ENA types, and though they do not rule out historical or even ongoing low levels of gene flow, they do indicate substantial genetic divergence among types, greater than reported among the majority of comparisons in a recent review of conspecific divergence ( Heller and Siegismund 2009). In that review, comparisons that exhibited G′ ST levels similar to sympatric killer whale types typically involved species where extrinsic barriers to gene flow existed and/or populations exhibited local adaptation (e.g., European wild boars separated by the Alps [ Scandura et al. 2008] and locally adapted Atlantic salmon [ Dionne et al. 2008]).

Discussion

Killer whale phylogenetics has been troublesome because of the extremely low levels of diversity found in the mitochondrial control region, so phylogenetic inference was weak or nonexistent ( Hoelzel et al. 2002; LeDuc et al. 2008). With highly parallel sequencing technologies, we have developed methods to sequence and assemble whole mitochondrial genomes from representative geographic and ecotype samples to provide strong inference of killer whale evolutionary patterns for the first time. The percent divergence among killer whale types was typically ≥50% higher in the control region than over the whole mitogenome (data not shown), suggesting that simply adding other short segments of mtDNA to the analysis would not significantly improve phylogenetic resolution. Additionally, Bayesian analysis in two phases allowed us to provide a much more accurate and precise date for the most recent common ancestor of all killer whales, and to use that date to estimate divergence times for each of the killer whale types.

Our estimated dates of divergence based on the entire mitogenome are much older than those inferred from short mitochondrial and nuclear loci. Previous studies using mitochondrial control region sequences and microsatellites have inferred that there was a Pleistocene bottleneck ∼145,000-200,000 yr ago that reduced variation in killer whale populations globally, followed by recent divergence among the known ecotypes in high-latitude coastal regions. The divergence times were estimated at 20,000-40,000 yr, with wide confidence intervals ( Hoelzel et al. 2002, 2007). Using these inferences as our hypotheses, we used whole mitogenomes to infer killer whale evolutionary patterns, and our results indicate much deeper initial separation (either geographic or ecological) between the mammal-eating Transient clade in the North Pacific and a second clade in the Atlantic or lower latitudes ∼700,000 yr ago, followed by ecological and/or geographical diversification of the second clade into the present day types at high latitudes, including secondary contact with Transients. These splits between types date from ∼150,000-700,000 yr ago rather than 20,000-40,000 yr ago, consistent with species or subspecies level designations. Given the clear lack of phylogenetic information in mitochondrial control region sequences, and the high mutation rates that could cause microsatellites to reach saturation over the time periods that we have inferred from mitogenomes, we believe the mitogenome data provide much stronger support for inference of divergence times.

Recent reviews on subspecies definitions in general have recognized the difficulty in coming up with criteria that will work for defining subspecies and species in all taxa, but they generally agree that data should support discreteness of the subspecies in relation to the remainder of the species and biological significance of the subspecies ( Haig et al. 2006). Species concepts are no closer to being universally accepted, but De Queiroz (2007) pointed out that all such concepts agree that species are separately evolving metapopulation lineages, and their delineation is primarily done by accumulation of lines of evidence. Using these criteria, we argue that the combined genetic, morphological, and behavioral evidence of divergence among sympatric types in the high-latitude regions of the North Pacific and Southern Ocean support the recognition of these types as separately evolving metapopulation lineages, and the elevation of three types to species, and several others to subspecies status.

It has previously been suggested that the Southern Ocean B and C types warrant species status on morphological grounds under the biological species concept (BSC), pending confirmation from genetic studies ( Pitman and Ensor 2003; Pitman et al. 2007). The genetic data presented here provide such confirmation, demonstrating that the two pagophilic (ice-associated) forms (B and C) are reciprocally monophyletic and form sister taxa substantially divergent from both open-water type A and all other killer whales. Therefore, we recommend that they be designated as distinct species that have diverged from one another for ∼150,000 yr and suggest that further analysis of nuclear sequence data should be performed for confirmation.

Our mitogenome data also indicate that the North Pacific Transients should be considered an independent species. Not only are they ecologically and morphologically distinct from other high-latitude killer whales, but genetically they are the most divergent type, diverging from all other killer whale types ∼700,000 yr ago. Taxonomic status for the Antarctic A type, North Atlantic types, and North Pacific Resident and Offshore types is less clear due to limited morphological divergence or limited morphological and ecological information, and/or small genetic sample sizes. As such, lines of evidence are not strong for species designation, and we recommend subspecies status pending additional nuclear sequence and morphological data.

Low levels of mtDNA variation have limited our ability to resolve evolutionary patterns in killer whales and some other cetacean species. The ability to use whole mitogenome sequences has allowed resolution of phylogeographic patterns. In killer whales these patterns are consistent with historical ecological specialization of small populations (or even single maternal groups) in each region reinforced by either temporary allopatry or in sympatry with social and behavioral isolating mechanisms. Given the typically very small population sizes of killer whale populations, numbering in the low hundreds to thousands, with higher densities in high-latitude coastal regions ( Barrett-Lennard and Ellis 2001; Forney and Wade 2006), monophyly might arise quickly in divergent types with little or no female dispersal ( Parsons et al. 2009), or dispersal limited to groups with similar vocal and behavioral patterns ( Baird et al. 1992; Baird 2000).

The limited sampling in lower latitudes, where diversity is relatively high but density is typically low ( Forney and Wade 2006), may mean that we have missed sharing of haplotypes across ocean basins in subtropical and tropical waters, but the patterns for the high latitudes are strongly supported by the more extensive sampling presented here. Most recognized types (except ENA types) have fixed differences in the mitogenomes, indicating independent evolution of each type. The pattern of relatedness among clades is consistent with the independent evolution of feeding specialization in different ocean basins, and apparent diversification of most types within each ocean basin, with the exception of the early separation of Transients from all others.

Type-specific prey specialization largely defines the ecological roles of killer whales and also determines their exposure to human impacts such as fisheries depletion of prey and bioaccumulation of pollutants. Each of these potential species, subspecies, or ecotypes represents a top predator in its ecosystem (or multiple top predators in areas where they are sympatric). As such, and because they are globally distributed, killer whales are critical components of the ocean ecosystems, and represent substantial biological and ecological diversity. Human impacts including over-fishing, persistent organic pollutants, and climate change are already affecting some killer whale populations (e.g., Hickie et al. 2007; Krahn et al. 2007a). Establishing appropriate taxonomic designations is critical for understanding the ecological impacts and conservation needs of these important marine predators, and for maintaining biological diversity and ecosystem health.

As indicated in this killer whale case study, previously reported limitations of using short DNA sequences can be overcome by using whole mitogenomes. High-throughput mitogenomics provides a new tool for intra- and interspecific phylogeography that addresses many of the problems of limited diversity and variable mutation rates and patterns found in short segments of mitochondrial loci. In addition, the long sequences provide both greater power for phylogenetic inference, and greater precision in estimation of divergence times. We expect that, as sequencing technologies continue to allow more samples, more sequence, and lower cost, the application of mitogenomics will become the default approach to phylogeography, as was previously the use of control region and cytochrome b sequence analysis.

Methods

DNA extraction and long-range PCR amplification

Skin biopsy samples were obtained from free-ranging killer whales by dart biopsy (e.g., Barrett-Lennard et al. 1996), or from stranded animals. Samples were selected to cover the broadest geographic range as well as genetic and killer whale type diversity. For the mitogenome analysis, most samples were selected from separate collection dates and, when known, identified groups to minimize chances of collecting close relatives or replicate individuals, except in the Southern Ocean, where all samples that had been assigned to one of the three types were included in the sample list (though not all were successfully sequenced). The sequenced sample set included: five (four, after removal of duplicate samples) Antarctic type A (Ant_A), 18 (15) Antarctic Type B (Ant_B), 39 (36) Antarctic type C (Ant_C), five ENP offshore, 11 ENP resident, 17 ENP transient, 12 ENP unknown, 12 eastern tropical Pacific (ETP) unknown, one Gulf of Mexico (unknown), one Newfoundland western Atlantic (unknown), one western South Pacific (New Zealand, unknown), 20 ENA Type 1, one ENA Type 2. In the Antarctic sample sets, we used all available samples, including one to four individuals each from 11 social groups of type C, and one to seven individuals from six social groups of type B whales. In the ETP, multiple (two to four) samples from four social groups were included in the analysis. All other samples are thought to be single samples from a social group. Sample collection locations and types are shown in Figure 1, and additional sample information is shown in Supplemental Table S1.

DNA was extracted using a variety of common extraction methods, including silica-based filter membranes (Qiagen), standard phenol/chloroform extraction (modified from Sambrook et al. 1989), and lithium chloride ( Gemmell and Akiyama 1996). Outgroup sequences were obtained from the NCBI GenBank or generated for this study (Supplemental Table S2).

PCR primers were designed from alignment of published whole mitochondrial genomes of other cetacean species, and partial mitochondrial genome sequences of killer whales to amplify the whole mitogenome in two to five overlapping fragments (Supplemental Table S3). PCR conditions for long-range amplification are given in Supplemental Table S3.

454 Life Sciences (Roche) sequencing

PCR products were quantified using Nanodrop (Thermo Scientific) or QuantIt Pico Green (Invitrogen) and pooled in equimolar concentrations for each sample. Samples were made into shotgun sequencing libraries following the manufacturer's instructions (454 Life Sciences [Roche]). Sample pools were grouped into sets, and within each sample set individual libraries were made to contain a different multiplexing identifier (MID) allowing for the combining of the libraries prior to emulsion PCR. Libraries were tagged for multiplexing according to the manufacturer's instructions (454 Life Sciences [Roche]) or Meyer et al. (2008). Sequencing libraries were quantified by qPCR ( Meyer et al. 2007) and pooled at equimolar concentrations. Library pools were divided among regions on GS FLX and Titanium sequencing runs. Sequences for 66 unique killer whale mitogenome haplotypes were deposited in GenBank (accession nos. GU187153-GU187164, GU187166-GU187219), as well as new mitogenome sequences for three outgroup species (accession nos. HM060332-HM060334). All accession numbers used for analysis are listed in Supplemental Table S2.

Microsatellites

A set of 26 microsatellite loci was used to genotype all Antarctic samples and samples collected across the northern North Pacific for population analysis and identification of samples representing duplicate biopsy sampling of the same individual. Forty-four samples were intentionally genotyped in duplicate to estimate error rates, and an additional 15 samples were found to be duplicate samplings of the same individual. One of each pair of unintentional duplicates was removed prior to statistical analysis. Sample sizes (after removal of duplicates) were: Transient, 126; Resident, 245; Offshore, six; Antarctic A, eight; Antarctic B, 15; Antarctic , 42. To test for genotyping errors, we compared replicated genotypes across all loci for replicated samples, and found a per-allele error rate of 0.2%, which is in the low range for published studies ( Morin et al. 2010). Population differentiation was calculated using G ST and Hedrick's G′ ST to control for the effect of heterozygosity, using the program SMOGD ( Crawford 2010). The approximate harmonic mean ( H) was calculated from the mean and variance across loci using the equation where A = average divergence across loci and var( D) = variance of divergence across loci (SMOGD website, http://www.ngcrawford.com/django/jost/).

Sequence assembly and phylogenetic analysis

Sequence reads for each sample were sorted by tag sequences, and a single sample was assembled de novo into a single 16,388-bp contig using 454 de novo Assembler software (Roche Applied Science). The consensus sequence and assembly reads were exported as an ACE file and edited with Consed ( Gordon et al. 1998), and used as the reference sequence for all subsequent assemblies using the 454 Reference Mapper software (Roche Applied Science). Consensus sequences were aligned in Sequencher (v.4.7, Gene Codes Corporation) or GENEIOUS (Biomatters Ltd), and ambiguities in polynucleotide repeats were individually checked in the 454 Reference Mapper assembly viewer and edited in Sequencher or GENEIOUS. For a region of between nine and 14 Cs in a row (positions 1130-1144 in the original alignment), and another region of seven to eight As in a row (positions 5210-5217), the assembly was unreliable, so the regions were shortened to a fixed set of nine Cs and seven As, respectively, for phylogenetic analysis to avoid introducing potentially erroneous variation. Eight samples were sequenced twice and analyzed for differences between replicates. Sequence alignments of other cetacean sequences and killer whale sequence were performed using Clustal v2.0.4 ( Larkin et al. 2007). A figure showing variable sites is shown in Supplemental material S4.

Neighbor-joining trees (MEGA4; Tamura et al. 2007) were constructed initially to select a subset of samples that represented the diversity in the killer whale clades. Bayesian phylogenetic trees and estimates of time since divergence of clades were conducted using BEAST v1.4.8 ( Drummond and Rambaut 2007). The HKY nucleotide substitution model was used, with relaxed clock and a Yule speciation process. We performed two sequential analyses to first estimate divergence times for the genus Orcinus, then for types within killer whales. In the first analysis, posterior distributions for divergence times of other cetaceans were used to estimate the divergence time for killer whales, using a set of seven samples representing each of the killer whale clades (Supplemental Table S5). The posterior distribution of divergence time for Orcinus from this analysis was then used as a prior distribution with all unique haplotypes to generate the killer whale phylogenetic tree and divergence time estimates for types. The phase I analysis used a burn-in period of 100,000 Markov chain Monte Carlo (MCMC) steps, 100 million total MCMC steps, and samples taken every 1000 steps. Phase II analysis was identical, except that the burn-in period was 80,000 and 80 million MCMC steps were used. Acceptable mixing and convergence to the stationary distribution were checked by visual inspection of posterior samples. Effective sample sizes were 1701 for Orcinus in the phase I analysis, 2700-5500 for type clades in the phase II analysis.

Acknowledgments

We thank the many people who provided tissue samples that allowed this analysis to be completed, including Gísli Víkingsson, MRI, Reykjavík; Nils Øien, IMR, Bergen; Renaud de Stephanis and Philippe Verborgh, CIRCE; and Bob Reid, Scottish Agricultural College. All samples in the US were collected by or transferred to the SWFSC under NMFS/MMPA and CITES permits. Samples analyzed in Copenhagen were collected under permit and transferred under CITES permit. We thank Michi Hofreiter, Matthias Meyer, and Simon Ho for advice on methods; and Bill Perrin, Kelly Robertson, Barb Taylor, Paula Olson, Malgorzata Pilot, the SWFSC subspecies journal club, and three anonymous reviewers for helpful discussion and help with the manuscript. We thank Rich Cosgrove for helping to generate the sample map. We thank Jon Nowacki, Jane Hutchinson, and Teri Mueller for project coordination and software assembly of 454 sequence reads. Support for this research was provided by Roche Applied Science, the Danish National Science Foundation, The Marie Curie Actions "Genetime" grant, Marine Directorate of the Scottish Government, Systematics Research Fund of the Linean Society, the Northwest Fisheries Science Center, and the Division of Protected Resources, Southwest Fisheries Science Center, NOAA National Marine Fisheries Service. R.L.P. was supported in part by a grant from the National Science Foundation (OPP-0338428).

Footnotes

# data[].attributes.attachment_link.title
Complete mitochondrial genome phylogeographic analysis of killer whales (Orcinus orca) indicates multiple species

# data[].attributes.attachment_link.description
Killer whales ( Orcinus orca) currently comprise a single, cosmopolitan species with a diverse diet. However, studies over the last 30 yr have revealed populations of sympatric "ecotypes" with discrete prey preferences, morphology, and behaviors.

# data[].attributes.body
Surprisingly, different populations of orcas have fill different roles in their ecosystems. This paper explores the various ecologies of several different population across the globe.

Source: Bruyn, P. J. N. D., C. A. Tosh, and A. Terauds. 2012. Killer whale ecotypes: is there a global model? Biological Reviews 88:62–80.

# data[].attributes.body
Orcas are one of, if not the most, widely distributed mammal species (other than people, of course). They can be found throughout the world's oceans, but generally prefer cold-water areas, often close to shore where food is most abundant (with exception to one open-water ecotype). There also appear to be distinct geographical populations, such as those in the North Pacific and around South Africa.

# data[].attributes.body
This may come as a surprise, given how charismatic this species is. However, because of their wide distribution, only specific populations have been estimated, not necessarily the species as a whole. There are also large gaps in information in areas of the Indian, South Pacific, and Southern Atlantic. The most recent estimate of minimum total population size was around 50,000 individuals worldwide.

# data[].attributes.body
Note the disparity in the population size between this and what the IUCN estimated. This further emphasizes how little we truly know about the total orca population size.

# data[].attributes.body
The name "killer" whale is a well-earned title for these apex predators. Orcas have an incredibly diverse diet, having been documented feeding on 140+ species! These can include fish, seabirds, rays, squid, penguins, seals, sharks, sea turtles, other whales, and the occasional moose. That is not to say, however, that every orca eats all of these animals. Each of the aforementioned ecotypes appears to have a specialized diet and hunting strategies. If you want to know more about the specific diets of each ecotype, you can visit:

# data[].attributes.attachment_link.readable_text
Food Preferences & Resources

Killer whales are top-level predators in the ocean. Killer whales are the largest predator of warm-blooded animals alive today.

Globally, killer whales appear to have an extremely diverse diet. Yet, individual ecotypes or populations are often extremely specialized. In many parts of the world, killer whales prey on fishes or marine mammals, but not both.

Worldwide, killer whales have been observed preying on more than 140 species of animals, including many species of bony fish, sharks and rays, and 50 different species of marine mammals.

Killer whales have also been reported to eat many other types of animals including leatherback sea turtles, dugongs, moose, and penguins and other seabirds.
Antarctic small type B killer whales have been observed hunting penguins like these Adélies.

Antarctic type A killer whales have been observed hunting southern elephant seals.
Each killer whale ecotype has a fairly specific diet.

The five forms of Antarctic killer whales differ in their diet:

Type A whales eat mostly Antarctic minke whales and have also been observed hunting southern elephant seals.

Minke whales are hunted by the North Atlantic type 2 killer whales in the northern hemisphere and by the Antarctic type A and large type B ecotypes in the southern hemisphere.

Large type B whales eat mainly seals, especially Weddell seals, and also hunt minke whales.

Small type B killer whales have been observed hunting penguins and are believed to mainly eat fishes.

Type C killer whales mostly eat Antarctic toothfish (Dissostichus mawsoni).

Little is known about the diet of type D killer whales, however, they have been observed preying on Patagonian toothfish (Dissostichus eleginoides) caught on longlines.

The feeding habits of resident and transient whales of the eastern North Pacific Ocean differ.

Resident whales spend about 60% to 65% of daylight hours foraging for fishes. Salmon make up 96% of their diet; Chinook salmon (Oncorhynchus tshawytscha) is the preferred species. Their diet is highly specialized and this dependence may be a limiting factor for this population. To a much lesser degree, residents are also known to eat one species of squid (Gonatopsis borealis) and 22 other species of fish including rockfish (Sebastes spp.), Pacific halibut (Hippoglossus stenolepis) and Pacific herring (Clupea pallasi). There is no evidence of resident killer whales eating marine mammals.

The eastern North Pacific resident killer whales prefer Chinook salmon.

Transient whales spend about 90% of daylight hours foraging. They primarily eat marine mammals including seals, sea lions, walruses, baleen whales, other toothed whales, and occasionally sea otters.

The transient ecotype in the eastern North Pacific hunt marine mammals including sea otters.

Researchers theorize that the divergent, specialized feeding habits of resident and transient killer whales help prevent these two groups of whales from competing with each other for food.

Such extremely different feeding habits, which is not known to occur in any other sympatric mammal species, has also resulted in significant differences in vocalizations, echolocation, group size and behavior between the two ecotypes.

The diet of offshore killer whales in the northeastern Pacific include fishes such as salmon (Oncorhynchus spp.), sculpin (Cottus spp.), Pacific halibut (Hippoglossus stenolepis), and Pacific sleeper sharks (Somniosus pacificus).

In the North Atlantic, the type 1 killer whales consume a varied diet that includes seals and small, schooling fishes such as herring and mackerel. Type 2 killer whales specialize in cetacean prey including dolphins, porpoises, and baleen whales such as minke whales.

Although rarely seen, killer whales in Hawaiian waters seem to have a more varied diet including humpback whales, dolphins, octopuses and squids.

In the North Atlantic, type 1 killer whales hunt schooling fishes such as these herring.

The diet of killer whales in Hawaiian waters includes dolphins..
Food Intake

At SeaWorld parks, adult killer whales eat approximately 1% to 3.5% of their body weight in food per day.

Growing calves eat more - as much as 10% of body weight during growth periods.

At zoological parks, calves begin to take a few fish at about two to three months.

A killer whale's lower teeth emerge at about 11 weeks.

By the age of one year, calves at SeaWorld eat 23 to 27 kg (50 to 60 lbs.) of herring, smelt, and squid per day.

Killer whales don't chew their food. They swallow their food whole, or they may tear or shred it.

Methods of Collecting Food

Killer whales often hunt cooperatively in pods for food.

Salmon-eating resident killer whales in the North Pacific often pursue prey singularly or in small groups. After a successful kill they regularly (75% of the time) share their fish, usually family members and particularly offspring.

At times killer whales work together to encircle and herd small prey before attacking. The comparatively large pod size of resident whales is an advantage when herding a school of fish.

Researchers observed Norwegian killer whales hunting cooperatively using a "carousel-feeding" technique. They cooperatively herded small fishes into a tight ball close to the surface. Then the whales stunned the fishes with their tail flukes and ate the stunned fish.

To hunt a large baleen whale, a pod of killer whales may attack the whale from several angles. One attack was witnessed by SeaWorld researchers. About 30 killer whales attacked an 18.2 m (60 ft.) blue whale. Two killer whales stayed ahead and two brought up the rear while the others surrounded the blue whale from the sides and underneath in an apparent effort to prevent escape. Some leaped onto its back. The whales took turns biting flesh and blubber from their prey. After five hours the pod broke off the attack.

Around New Zealand a group of seven killer whales were observed hunting a shortfin mako shark (Isurus oxyrhinchus). As the shark attempted to retreat, it was bitten and held by its tail and then around its girth and head until consumed. Another group of killer whales was filmed attacking a blue shark (Prionace glauca) by striking it hard at the surface of the water with their tail flukes.

Transient pods are known to "sneak attack" marine mammals. These small groups most often hit quietly or silently. Other observed transient hunting techniques include driving and trapping groups of Pacific white-sided dolphins in confined bays and ramming sea lions with their heads or stunning them with tail fluke swats before taking the animal underwater and drowning it.

In the Antarctic, individual killer whales slide out onto ice floes to hunt penguins. Similarly, killer whales sometimes slide up onto sand bars or beaches to hunt pinnipeds such as juvenile elephant seals.

Killer whales sometimes hit ice floes from below to knock penguins and pinnipeds into the water. When an ice floe is too big to be overturned, Antarctic type B killer whales will swiftly swim side-by-side at the ice floe, diving below the floe at the last second, to create a wave large enough to wash a hauled out seal into the water.

Sometimes killer whales feed in connection with fisheries operations, eating fishes that slip from the nets and bycatch (nontarget fish caught during a fishing operation) discarded by fishermen. In some areas, killer whales congregate near longline boats and feed on the hooked fish.

To hunt a large baleen whale, a pod of killer whales may attack the whale from several angles.

Prey such as these sea lions, may not be safe from killer whales even on land.
Killer whales also hunt individually.

In the Antarctic, killer whales slide out onto ice floes to hunt penguins. Similarly, killer whales sometimes slide up onto sand bars or beaches to hunt sea lions.

Killer whales sometimes hit ice floes from below to knock prey into the water.

An encounter between a great white shark (Carcharodon carcharias) and killer whales was documented off of Southeast Farallon Island near San Francisco, California. shark

Two killer whales were in the area feeding on a California sea lion (Zalophus californianus) - a favored food of great whites. Perhaps the smell of fresh sea lion blood drew the shark to the area, but once one of the killer whales sighted the great white it immediately charged and contacted the shark under water.

The killer whale pulled the 3 to 4 m (10 to 13 ft.) shark to the surface in its mouth and the killer whales consumed sections of the great white such as its enormous liver.

This is certainly no indication of what may happen every time killer whales face great whites, but it does demonstrate the variety of a killer whale's diet.

# data[].attributes.attachment_link.keywords[]
killer whales are top-level predators in the ocean. killer whales are the largest predator of warm-blooded animals alive today.

# data[].attributes.attachment_link.description
Killer whales are top-level predators in the ocean. Killer whales are the largest predator of warm-blooded animals alive today. Globally, killer whales appear to have an extremely diverse diet. Yet, individual ecotypes or populations are often extremely specialized. In many parts of the world, killer whales prey on fishes or marine mammals, but not both.

# data[].attributes.attachment_link.title
Orcas Vs Shark: Killer Whales Take Down Tiger Shark

# data[].attributes.attachment_link.title
Killer Whale vs. Sea Lions | National Geographic

# data[].attributes.attachment_link.readable_text
Bowhead whales in Russia's Okhotsk Sea are endangered, struggling to recover from threats both past (commercial whaling) and present (warming seas).

But that doesn't faze the local orcas, which have become skilled at hunting and killing the whales.

For the first time, scientists have witnessed, thanks to drone video, how the predators work as a team to surround and kill a juvenile bowhead, which can be three times heavier than an adult orca. ( Read how orcas work together to whip up a meal.)

"We've known for a long time that orcas can hunt grey and bowhead whale calves by separating them from their mothers, but it's interesting that here they kill a bowhead aged between one and five years old," says Olga Shpak, a biologist at the Severtsov Institute of Ecology in Russia who saw the hunt firsthand. The juvenile bowhead was already over 26 feet long and weaned from its mother, she says.

But this orca family, known to scientists since 2011, know what they're doing: They specialize in hunting juvenile bowheads. The matriarch's nickname is Whale Killer.

"Once they start to learn something, orcas will keep perfecting the skill, and this family has honed their hunting to require minimal energy," Shpak says. ( See an interactive graphic of orca hunting.)

Phil Clapham, leader of the Cetacean Assessment and Ecology Program at the Marine Mammal Laboratory in Seattle, Washington, says by email that whales often carry visible scars from failed orca attacks, but such events "are rarely observed."

"This is unique and extraordinary footage."

Adolescence is awkward for bowheads as they lose fat and bone acquired in their first year of life, redirecting body resources to develop their massive head and feeding apparatus, particularly the baleen plates that sieve zooplankton, their food source.

Unlike with bowhead calves and smaller whale species, such as minke, the orcas' hunting strategy in this situation went beyond drowning their prey. ( See the surprising reason why orcas attacked this blue whale.)

"This whale is too big to be drowned, so they ram its side, crushing the ribs," says Shpak, who analyzed the video footage.

While the matriarch attacks in this manner, other pod members have assigned roles. The young orca swims near the whale's head, blocking its escape, while other adult orcas pull the animal by the fins away from shallow waters.

"They can only kill the whale in deep waters because the orca needs to accelerate and gather enough speed for the strike," says Shpak, who has seen this pod hunting bowheads four or five times. ( See National Geographic's whale pictures.)

Orcas likely killed six bowheads in the Okhotsk Sea's Academy Bay in 2016 alone. The hunting pressure may be why the local whale population isn't bouncing back after commercial whaling in the 19th century and illegal Soviet whaling in the 1960s and '70s, Shpak says. Since the 1980s, Okhotsk bowhead numbers have hovered around 400.

"Whether such attacks represent a threat to the population is not clear," notes Clapham. "They are almost always on calves or yearlings (not adults), and we don't know how often they are successful."

Shpak adds "the presence of bowheads there is paradoxical to begin with," because the bays of the western Okhotsk Sea are much warmer and less salty than the species' typically Arctic habitat. Colleagues studying bowheads in the Arctic routinely refer to the Okhotsk whales as "tropical," she jokes.

But that's also why the rare Okhotsk bowheads could be "a great model for studying how an Arctic species adapts to a warming climate."

# data[].attributes.attachment_link.title
Orcas Team Up to Kill Whale in Raw, First-Ever Video

# data[].attributes.attachment_link.description
Bowhead whales in Russia's Okhotsk Sea are endangered, struggling to recover from threats both past (commercial whaling) and present (warming seas). But that doesn't faze the local orcas, which have become skilled at hunting and killing the whales.

# data[].attributes.body
This study proposes the idea that the degree of sociality may differ with varying ecological roles. They compare the social cohesion and behaviors of Atlantic orcas that hunt mammals and those that hunt fish. They also compare these orcas against the Pacific ecotypes.

Source: Beck, S., S. Kuningas, R. Esteban, and A. D. Foote. 2011. The influence of ecology on sociality in the killer whale (Orcinus orca). Behavioral Ecology 23:246–253.

# data[].attributes.attachment_link.readable_text
Abstract

The persistence and size of social groups can be plastic and governed by ecological selection or be under greater genetic control and constrained by phylogenetic inertia. Comparing sociality of phylogenetically divergent populations under the same ecological conditions or between groups within a population under different ecological conditions can identify the relative influence of ecological selection on group formation. Here, we compare the size and persistence of social groups within a community of Atlantic killer whales, comparing between data collected from an area around Scotland where the whales have mainly been seen to hunt seals and data collected from an area around Iceland where the whales have mainly been seen to hunt herring. Additionally, we compare the observed social structure with that of previously studied Pacific ecotypes. Atlantic killer whale groups in both locations had a stable long-term primary social tier (association index level > 0.8) similar to that of Pacific killer whales. However, associations between these groups were much lower when hunting for seals than for fish in both the Atlantic and the Pacific. The occurrence of these differences in sociality between Atlantic groups, which are linked in a single social network, suggests that ecological selection partially determines sociality in this species. Furthermore, if sociality was constrained by phylogenetic inertia, then the Atlantic killer whales would all be expected to be more similar to the Pacific fish-eating ecotype than the more phylogenetically distant Pacific mammal-eating ecotype. Our study suggests that sociality in killer whales is to some extent plastic and can be adapted to the local ecological conditions.

INTRODUCTION

Sociality can increase both individual and inclusive fitness when groups consist of close kin. Cooperative interactions within a group such as alloparental care, transmission of socially learned behavior, and communal defense can increase access to resources or mates ( Maynard Smith 1964; Crook and Gartlan 1966; Alexander 1974; Packer and Ruttan 1988; Packer et al. 1990; Connor et al. 1992, 1999; Giraldeau et al. 1994; Clutton-Brock et al. 1998; McComb et al. 2001; Rendell and Whitehead 2001). However, there can be fitness costs of sociality, including parasite and disease transmission, intra- and interspecific competition, and increased probability of detection by predators or prey ( Wrangham et al. 1993; Clutton-Brock et al. 1998; Altizer et al. 2003; Nunn et al. 2008). These extrinsic ecological factors can govern both the size and persistence of social groups.

However, among some taxa, behavioral traits such as social structure can show little evidence of adaptive convergent evolution due to ecological conditions, instead the differences are attributable to phylogenetic distance between these taxa ( Chapman and Rothman 2009). Determining the relative influence of ecological conditions on sociality can be achieved by comparing social structure in groups within a population inhabiting different ecological conditions or by comparing social structure in phylogenetically distant populations inhabiting similar ecological conditions ( Chapman and Rothman 2009).

Here, we apply this approach to compare sociality in groups within a population of Atlantic killer whales ( Orcinus orca) using data collected under distinct ecological conditions (e.g., hunting herring in Icelandic waters and hunting seals off Scotland). We then compare these observations with published data on 2 divergent Pacific killer whale ecotypes, one a mammal-eating specialist and the other a fish-eating specialist ( Ford et al. 1998), which differ in social structure ( Baird 2000). The phylogenetic distance between Atlantic lineages and the Pacific mammal-eating "transient" ecotype is much greater (time to most recent common ancestor, TMRCA ∼0.7 MYA) than the phylogenetic distance between Atlantic lineages and the Pacific fish-eating "resident" ecotype (TMRCA ∼0.2 MYA; Morin et al. 2010). Therefore, under strong phylogenetic inertia, we would expect the social structure of Atlantic groups not to vary due to ecological conditions and to be most similar to the Pacific resident ecotype. However, if environmental conditions do influence social structure and phylogenetic inertia is weak, then sociality in Atlantic killer whale groups hunting seals should be more similar to that of the Pacific transient ecotype than to either Atlantic or Pacific fish-eating groups.

MATERIALS AND METHODS

Study sites and data collection

The main study site consisted of Caithness: the northeastern tip of the Scottish mainland and the Northern Isles, which consist of 2 island archipelagoes, Orkney and Shetland, approximately 25 and 50 miles, respectively, northeast of Scotland. Hereafter, this study site is referred to as Scotland. The occurrence of killer whales in this area is highly correlated with the harbor seal ( Phoca vitulina) pupping season during the summer months ( Bolt et al. 2009). Observed predation events, group follows, and collected prey remains suggest that the killer whales photo-identified in Scottish nearshore waters in this area are mainly predating seals when in this area ( Foote et al. 2010; Deecke et al. 2011). Killer whale groups have been photo-identified further offshore around Shetland feeding on herring in the summer ( Deecke et al. 2011) and mackerel in the winter ( Foote et al. 2010) but have not yet been linked by association to the nearshore groups. Photo-identification data were collected from 17 encounters during 2 dedicated field seasons conducted in Shetland in summer 2008 and 2009 (see Foote et al. 2010; Deecke et al. 2011). Opportunistic photographs from Scotland taken by local wildlife photographers were collected between 2005 and 2010 (see Foote et al. 2010). All opportunistic photographs were taken between March and August, with over 80% being taken in the months May-July. Photo-identification data were collected on the herring grounds off East Iceland between 1981 and 1999 in areas where herring shoals were acoustically detected and/or the whales were seen feeding on shoals of herring at the surface ( Sigurjónsson et al. 1988). No predation of mammals was recorded in any of the Icelandic encounters. See Foote et al. (2010) for details on data collection.

Photographic analysis

All analysis was based on photo-identification data only and not visual identification in the field. Photographs in which the fin and saddle filled less than 10% of the photograph, not in focus, poorly lit or in which the animal was not parallel to the camera were excluded. Both left side and right side photographs were included. The best photograph of each individual from each encounter was then selected. Individuals were identified based on the presence of long-lasting markings, such as fin-nicks, or scars or pigmentation on the saddle patch (see Similä and Lindblom 1993; Figure 1). Photographic matching of Scottish data and between Scottish and Icelandic data was performed by an experienced observer (A.D.F.) and then double checked by a second experienced observer (S.K.); photographic matching between Icelandic encounters had previously been performed by an experienced observer (T. Similä; see Foote et al. 2010).

For some individuals, we were able to establish stage of maturity and sex class. The presence of secondary sexual characteristics could be used to identify adult males, and the development of these characteristics during the study period could be used to identify subadult males. The consistent close association of a calf could be used to identify a sexually mature adult female. Some female-sized individuals photographed off Scotland had been photographed off Iceland in the 1990s and had not developed secondary sexual characteristics and were therefore confirmed as adult females rather than subadult males. Lastly, the sex of some individuals was determined through observation of the gender-specific pigmentation in the genital area. Individuals were classified as adults, subadults (males ca. 15-21 years old), juveniles (ca. 3-14 years old), and calves (ca. 2 years old or younger).

Strength of associations

Association was defined as presence in the same group. We defined a group as all individuals showing a degree of coordinated behavior often surfacing within 5-10 s of each other and traveling within visual range of the observers (as per Baird and Dill 1996; Baird and Whitehead 2000). This could be determined from opportunistic photographs if individuals were not all caught in the same frame, by noting the time signature of the photo of each individual. Dedicated fieldwork encounters around Shetland were typically several hours in duration, and all members of the group were identified, except in one case where conditions cut the encounter short. Opportunistic encounters were often brief and not all individuals within the group may have been identified. Similarly, in Iceland conditions and group sizes mean that not all individuals present within the group in each encounter may have been photographed. The large numbers of groups aggregated on the Icelandic herring grounds meant that individuals photo-identified during the same encounter may not fit the definition of a group given above, which may confound comparison with the Scottish data. Analyses that did not require all members of the group to have been identified were therefore employed (see below). To reduce inaccuracies and biases associated with small sample sizes, most analyses were limited to individuals sighted in at least 4 different encounters following previous studies (e.g., Ottensmeyer and Whitehead 2003; de Stephanis et al. 2008; Tosh et al. 2008).

All association analyses were conducted using SOCPROG 2.4 ( Whitehead 2009) run in the MATLAB computing environment. The strength of association between dyads was measured using 2 indices of the frequency of co-occurrence: the half-weight association index (AI) and the simple ratio AI ( Cairns and Schwager 1987; Ginsberg and Young 1992). The simple ratio index generates a statistically unbiased estimate of association and is appropriate when association is defined by presence in the same group during a sampling period ( Ginsberg and Young 1992). However, the half-weight index can be more suitable when not all individuals within each group have been identified. As the inferences drawn were the same for both indices, and both were indicated as being good representations of social structure by high cophenetic correlation coefficient values (>0.9 for both indices for Iceland and Scotland), only the values of the half-weight AI are presented. The association matrix containing all individuals was displayed as a sociogram in which individuals are represented by points around a circle and the thickness of lines between points indicates the strength of association ( Whitehead and Duffault 1998). The association matrix containing all individuals seen on at least 4 different days was displayed as an average linkage cluster analysis ( Manly 1994) showing the average level of association between hierarchically formed clusters. The strength of association is indicated by the point of bifurcation on the x axis between individuals, which are arranged on the y axis ( Whitehead and Duffault 1998).

Permutation tests ( Bejder et al. 1998; Whitehead 1999) were used to test whether the observed association patterns were different than expected for random association in a population of the same size and with the same residency patterns as our study population. If the observed standard deviation (SD) of the pairwise association indices is significantly greater than those from the permuted data set, then this is taken as evidence that individuals have preferred or avoided associates ( Whitehead 1999). To ensure that P values were stable, 6 runs of the permutation test were generated with 20 000 permutations generated for each test using the simple ratio and half-weight indices in 3 runs each (see Ottensmeyer and Whitehead 2003; de Stephanis et al. 2008).

Persistence of associations

To investigate and model the temporal aspects of social structure, we used the standardized lagged association rate (SLAR; Whitehead 1995, 2007). The SLAR is the average probability given that individuals A and B are associated at time 0, that B will be identified later in a photograph of a randomly chosen group member at a time lag τ when A is also present ( Whitehead 1995). The SLAR is estimated by calculating

where c(A, t, τ) is the number of associates that were seen with individual A at both time t and time t + τ, and N(A, t) is the number of associates seen with individual A at time t. We then compared the SLAR at all time lags with the null association rate, that is, the SLAR expected if all individuals are associating at random, given the population size:

where P is the number of well-marked individuals in the analysis. Sampling periods were individual days, and the analysis was restricted to individuals encountered in at least 4 sampling periods as above. Standard errors were estimated using jackknife methods ( Efron and Gong 1983). Mathematical models representing simulated social structures ( Whitehead 1995) were fitted to the SLAR. The best-fit model was chosen as that which minimized the quasi Akaike's (1974) information criterion (see Burnham and Anderson 2002; Whitehead 2007).

Hierarchical tiers of social structure

To compare the number and level of social tiers in the social structure of killer whales photo-identified hunting seals around Scotland with those photo-identified on the Icelandic herring grounds and with the Pacific mammal-eating killer whales (using the data presented in Baird and Whitehead 2000), we displayed the results of the hierarchical cluster analysis as a knot diagram ( Wittemyer et al. 2005; Whitehead 2009). A knot diagram is a graph of the cumulative number of bifurcations plotted against a function of the AI ( Wittemyer et al. 2005; Whitehead 2009). We plotted the number of bifurcations directly against the negative logarithm of association level, which can be considered an association distance congruent with that used by Wittemyer et al. (2005). Sudden drops in the rate of bifurcation, termed "knots," can identify potentially useful levels at which to define clusters, and more than one knot can indicate hierarchical tiers of clusters ( Wittemyer et al. 2005; Whitehead et al. 2009). The significance of all potential putative knots was assessed by comparing the distribution of bifurcations per stepwise increment above versus below the knot values using the Wilcoxon two-sample test. The Wilcoxon two-sample Z statistics of all contiguous knots were compared, and the putative knots that maximized these statistics were used to delineate social tiers (see Wittemyer et al. 2005).

RESULTS

In the nearshore Scottish waters, we photo-identified a total of 37 well-marked individuals from 60 photographic encounters, 18 of which were identified in more than 4 sampling periods. With the exception of 4 individuals (18, 29, 30, and 31), all individuals were observed predating a mammal during dedicated fieldwork or clearly photographed predating a mammal in the opportunistic photographs in at least one encounter. All individuals were photographed following the shoreline around seal haulouts less than 20 m from shore.

The Icelandic data set consisted of 294 well-marked individuals from 550 photographic encounters. Thirty-seven individuals were identified in more than 4 sampling periods and were used for further analyses, including an individual also identified in Scottish nearshore waters (Iceland ID No. IF-4, Scotland ID No. 21). Six individuals were photographed in both Scotland and Iceland, and 4 of these were photographed feeding on seals in nearshore Scottish waters, therefore forming links in a network based on association between our 2 ecological conditions ( Figure 1). These links were based on associations and not one-off overlaps in occurrence in the same location, as individuals from Scotland were identified in multiple years in the Icelandic data set and in association with the same "Icelandic" individuals. Two individuals (Iceland ID No. I-1, Scotland ID No. 113; Iceland ID No. I-9479, Scotland ID No. 122) photo-identified off Iceland were also photographed in a group seen feeding on North Sea herring on the 1 July 2009 approximately 5 miles offshore of Shetland, they were not photographed in nearshore Scottish waters and were not included in further analyses. These 2 individuals and the group they were part of were also linked to the network in Figure 1; however, for clarity, the Shetland herring-feeding group is not included in the network figure.

Group size

Group size of the killer whales encountered in nearshore Scottish waters and observed predating on mammals ranged from 1 to greater than 15 ( Figure 2). The modal group size of killer whales encountered in nearshore waters around Scotland was 5 individuals both during dedicated fieldwork and when opportunistic encounters from Scotland were included ( Figure 2). The mean group size was 4.6 (SD = 2.6) from dedicated encounters and 5.8 (SD = 3.0) when opportunistic encounters were included. The sum of all associations, which is a similar measure to the "typical group size" of Jarman (1974), for individuals encountered in at least 4 sampling periods was 5.51 (SD = 1.58). The SD of the typical group sizes sensu Jarman (1974) was 1.42 indicating that there are no large differences in gregariousness or sociality among individuals within the data set.

Group size from a subset of 38 encounters from surveys in October and November 1986 on the Icelandic herring grounds (see Sigurjónsson et al. 1988) for which we had detailed notes ranged from 2 to 80 ( Figure 2). Taking the most conservative group size estimate from each encounter, the mean group size was 14.8 (SD = 12.0), significantly larger (Mann-Whitney U test: P < 0.01) than observed in nearshore Scottish waters.

Association strength

A sociogram of the half-weight index of association indicated that all identified individuals from nearshore Scottish waters were linked by association ( Figure 3). The average linkage cluster analysis ( Figure 4a) indicated that individuals encountered during 4 or more sampling periods were frequently sighted with preferred associates, with some individuals never being encountered without a preferred associate also being identified (e.g., ID Nos. 65 and 66; 12 and 13). The cophenetic correlation coefficient was 0.989 indicating that the dendogram was a good representation of social structure ( Whitehead 2009). The individuals sighted on 4 or more days were split into 3 clusters at an association level of 0.5 or more. As there was incomplete photographic coverage during opportunistic encounters, the absence of an individual from the photo-identification records of an encounter could result from failure to photographically capture that individual or its genuine absence from the group. The estimated association levels estimated here are therefore likely to be negatively biased. An adult male (ID No. 14) was not placed in any of the 3 clusters and was most frequently observed on his own ( Figure 4a). Two calves (ID Nos. 161 and 162) were born subsequent to previous encounters with the mother resulting in lower values in the terminal association node (the node with the weakest association within the group). The SD of the observed pairwise association indices was significantly higher than those from the permuted data sets (half-weight index: P = 0.00005; simple ratio index: P < 0.00005). Thus, we could reject the null hypothesis that individuals associated randomly.

The average linkage cluster analysis of the Icelandic data ( Figure 4b) had a high cophenetic correlation coefficient (0.908) indicating that it was a good representation of social structure ( Whitehead 2009), and the SD of the observed pairwise association indices was significantly higher than those from the permuted data sets (half-weight index: P = 0.00005; simple ratio index: P < 0.00005), allowing rejection of the null hypothesis that individuals associated randomly.

Persistence of associations

The SLAR between individuals identified at least 4 times in Scottish waters dropped after approximately 1 week but then appeared to stabilize at a rate that was above the null association rate (the rate expected if individuals were associating at random; see supplementary Material). This suggests that long-term relationships exist. However, the error bars estimated at approximately 12 days and at approximately 60 days cross the null association rate. Inspection of the resighting data indicates that the group containing individuals 27, 34, 72, and 73 was observed 8, 10, 60, 307, 361, 423, and 698 days before being identified in a large aggregation of 13 individuals all of which were photo-identified but which that particular group had not been associated with in any other encounter (see supplementary Material). These lags correspond to minimum values in the SLAR, and the low SLAR at these time lags appears to be largely an artifact of this single encounter with a large group. Therefore, the overall persistence of associations above random expectations at longer time lags appears reasonable. The best-fit model for the SLAR curve for individuals in each of the 3 groups was "constant companions," i.e., long-term consistent relationships ( supplementary Material).

The best-fit model for the SLAR curve for the Icelandic data was of 2 levels of association: constant companions (long-term consistent associations) and "casual acquaintances" (short-term associations; see Whitehead 1995; supplementary Material).

Hierarchical tiers of social structure

Significant knot values indicated points where association levels changed from persistent groups with high association between individuals to more fission-fusion type associations with a lower association level ( Figure 5). The concave down shape of the knot diagram indicates that the primary social tier (e.g., the association level with the largest amount of bifurcations) is at a high AI level for the Pacific mammal-eating transients, Scottish and Icelandic data. However, there was only a significant knot in the Scotland data and Baird and Whitehead's (2000) Pacific mammal-eating killer whale data, in both cases at AI = 0.84 (Scotland: Z = −2.201, P = 0.028; Pacific: Z = −1.992, P = 0.046). There were more bifurcations at high association levels in the Icelandic data and although nonsignificant, the knot with the highest Z statistic for changes in the slope was at AI = 0.86 ( Z = −1.604, P = 0.109), suggesting a similar primary social tier to the Scottish and Pacific data. There were further bifurcations at a range of AIs in the Icelandic data, suggesting more frequent or more persistent associations at a secondary social tier. However, interpretation of this is confounded by the Iceland data including possible aggregations rather than groups as defined above. There was no published Pacific "resident" dendrogram to compare the rate of bifuractions at different AI levels with. However, previous studies found that there was no dispersal from the natal matriline ( Bigg et al. 1990), which would suggest a primary social tier at AI = 1.0. Additionally, many matrilines are known to associate greater than 50% of the time; these social units are known as pods ( Bigg et al. 1990). More recent studies also suggest intermatriline associations at a wide range of AI levels >0.1 ( Parsons et al. 2009; Ivkovich et al. 2010).

DISCUSSION

Our results indicate that the primary social tier of the Atlantic groups consisted of long-term stable associations regardless of the ecological conditions. This cohesive primary social tier has been found in all studies on this species to date regardless of their prey (salmon Oncorhynchus sp.: Bigg et al. 1990; Parsons et al. 2009; Ivkovich et al. 2010; pinnipeds: Baird and Whitehead 2000; Tosh et al. 2008; and tuna Thunnus thynnus: Esteban Pavo 2008) and therefore appears to be relatively robust to ecological differences. Cohesive social groups have also been reported in other closely related species, for example, long-finned pilot whale Globicephala melas, short-finned pilot whale G. macrorhynchus, and false killer whale Pseudorca crassidens ( Shane and McSweeney 1990; Heimlich-Boran 1993; Ottensmeyer and Whitehead 2003; de Stephanis et al. 2008). Phylogenetic inertia may therefore play a role in partially determining the social structure of killer whale populations.

The second social tier, that is, the level of association between these cohesive groups, appears to be more plastic and influenced to some extent by ecological selection. Group sizes of killer whales hunting seals off Scotland in this study were on average, smaller, and more consistent in size than groups encountered on the Icelandic herring grounds. Similar results have been reported from the Pacific, of smaller more consistent group sizes of mammal-eating transient killer whales (mean of 3.9; SD of 1.9) compared with fish-eating resident killer whales (mean of 16; SD of 19.1; Zerbini et al. 2007). These differences in group size appear to result partly from limited dispersal from the primary social tier of mammal-eating groups ( Baird and Dill 1996; Baird and Whitehead 2000) but mostly from a lower level of association at the secondary social tier ( Figure 5).

Baird and Dill (1996) suggested that larger groups of mammal-hunting killer whales would suffer a cost due to an increased probability of detection by prey. In their study in British Columbia waters in which the prey species was harbor seal ( P. vitulina) in 95% of the 136 successful attacks, the most frequently observed and optimal group size for maximizing energy intake was 3 individuals ( Baird and Dill 1996). Previous experimental work using playbacks of killer whale calls found that harbor seals respond to the sounds of mammal-eating killer whale calls by diving away from the surface, which may make them more difficult to detect by echolocation ( Deecke et al. 2002). Norwegian herring also responded to playbacks of Norwegian herring-eating killer whale calls; shoals decreased in density by spreading out through the water column ( Doksæter et al. 2009). However, groups of killer whales use a coordinated foraging strategy to bring the herring close to the surface and herd it back into dense shoals ( Similä and Ugrate 1993; Similä 1997; Nøttestad et al. 2002). Therefore, detection by prey may be less costly for killer whales when feeding on pelagic fish compared with when feeding on seals. Further playback experiments simulating different group sizes could provide further insights into this potential constraint on sociality.

An additional variable that we were unable to control for when comparing between the 2 Atlantic study sites was that conditions can change over time and lead to temporal variation in sociality (e.g., Wittemyer et al. 2005; Erhart and Overdorff 2008; Chapman et al. 2010). Such a change has been observed in killer whales in the Northeast Pacific in which temporal variation in sociality has been correlated to variation both in salmon abundance and the occurrence of the Pacific Decadal Oscillation ( Lusseau et al. 2004; Parsons et al. 2009). East Iceland and the North Sea are subject to a simple bottom-up controlled food chain and are therefore sensitive to this climate variation ( Beaugrand 2004; Astthorsson et al. 2007). Values for the winter NAO index obtained from the Climatic Research Unit, University of East Anglia, Norwich, UK ( http://www.cru.uea.ac.uk/∼timo/datapages/naoi.htm) indicate that the NAO index was undergoing an upward trend during the collection of the Icelandic data but has been in a downward trend with greater variability during the collection of the Scottish data. Further data collection from the Icelandic herring grounds concurrent with data collection around Scotland are currently underway (see Samarra et al. 2010) and could help elucidate the relative effects of climate variability and prey species on sociality of these North Atlantic killer whales.

Although it is not possible to predict the ecological niche of the ancestral populations, the results do suggest that sociality is influenced by ecology to some extent rather than simply reflecting common ancestry. First, the social contact between the seal-hunting groups and the herring-hunting groups suggests that they are a part of the same population and therefore that there is variation in ecology and sociality within a population. Second, phylogenetic distance is less between these Atlantic lineages and the Pacific residents than between either and the Pacific transients ( Morin et al. 2010; Foote et al. 2011). If phylogenetic inertia constrained sociality, then it would be expected that all the individuals within the Atlantic population would have a social structure similar to the Pacific residents.

Killer whales observed hunting seals around Shetland are markedly similar in behavioral phenotype to the Pacific mammal-eating transient killer whale ecotype. Both hunt in small, silent, cohesive groups ( Baird and Dill 1996; Deecke et al. 2005, 2011). The groups observed hunting herring around Iceland are more similar in behavioral phenotype to the Pacific fish-eating resident ecotype, as they typically hunt in larger groups, but with greater variability in group size, and are highly vocal ( Simon et al. 2007). It appears these behavioral phenotypic traits that characterize each hunting strategy are to some extent plastic. The social links between the Atlantic groups observed using each hunting strategies are in contrast to the social isolation between the Pacific killer whale ecotypes ( Bigg et al. 1990). Previous studies have observed Norwegian groups hunting both seals and herring on different occasions ( Stenersen and Similä 2004). A study using long-term dietary markers found that within several maternal lineages, there was a range of stable isotope values consistent with trophic level differences in the diet; however, all these specimens had worn teeth suggesting a shared component of the diet ( Foote et al. 2009). The behavioral ecology of these Northeast Atlantic lineages therefore appears more consistent with specialization in foraging behavior at the individual- or group-level rather than population or ecotype level, and diet does not seem to be as exclusive as in the Pacific ecotypes. Theoretically, there should be no disadvantage to outbreeding between mammal-eating or fish-eating killer whales if all traits under selection are nonheritable and developed through social learning ( Hoelzel et al. 2007). It would therefore appear that an additional factor may be responsible for the differences in the level of social isolation between foraging specialists in the Pacific compared with the Atlantic. Sympatry between the Pacific ecotypes appears to result from secondary contact following an allopatric phase, i.e., the resident type migrated from the Atlantic in to the Pacific ( Foote et al. forthcoming). The behavioral plasticity within some North Atlantic lineages and links of association between foraging specialists would suggest that an allopatric phase could be an important determinant as to whether phenotype diversification leads to the development of socially isolated ecotypes in this species.

SUPPLEMENTARY MATERIAL

Supplementary material can be found .

FUNDING

Carnegie Trust for the Universities of Scotland, Marine Scotland: the Scottish Government; Scottish Natural Heritage; Shetland Amenity Trust; Iceland Air; and Northlink Ferries.

We thank all individuals and groups that contributed toward the database of photographs, including the contributors of Nature in Shetland, Shetland Sea Mammal Group, Brydon Thomason, Karen Munroe, Harriet Bolt, Sandra Abel Nielsen, Volker Deecke, Milaja Nykänen, Nicola Rehn, Alice Rocco, Adam U, Julia Vilstrup, and Hannah Wood. We especially thank Gísli Víkingsson and Tiu Similä for allowing access to the Icelandic photo-id database. Scottish Natural Heritage in Lerwick and the Shetland Amenity Trust and the Yell Sound ferry generously provided logistic support in Shetland. Luis Giminez, the editor, and 2 anonymous reviewers provided useful comments that greatly improved this manuscript.

References

,

,

University of Chicago Press

(pg.

-

)

,

,

,

,

pg.

,

,

pg.

,

,

2nd ed

,

,

,

,

# data[].attributes.attachment_link.title
influence of ecology on sociality in the killer whale ( Orcinus orca )

# data[].attributes.attachment_link.description
The persistence and size of social groups can be plastic and governed by ecological selection or be under greater genetic control and constrained by phylogenetic inertia. Comparing sociality of phylogenetically divergent populations under the same ecological conditions or between groups within a population under different ecological conditions can identify the relative influence of ecological selection on group formation.

# data[].attributes.body
Killer whales have some of the most complex and unique social structures in the animal kingdom. It is believed that these closely knit social groups are a part of what makes them such effective pack hunters. Unlike many other animal societies, orcas are matriarchal. Their most basic social group, called the maternal group, is centered around the mother and offspring, even the adult offspring. Several closely related maternal groups, like daughters' or cousins' groups, may come together to form a pod. Pods travel together and may be anywhere from 5 to 50 individuals. Many pods may form a community and members of these communities frequently socialize with one another. These communities are also marked by a distinct lack of aggression between members. However, members of different communities rarely interact with one another. There is also a fourth social designation: the clan. Clans consist of pods that have vocalizations in common, almost as though they were speaking the same language or dialect. Belonging to different clans does not prevent socialization, however. Different pods within the same community may also have their own behaviors, such as preferred hunting strategies or ways of greeting one another.

Sources:
OrcaLab. n.d. OrcaLab RSS. <https://orcalab.org/orcas/orca-social-organization/> Accessed 31 Mar 2020.
Understanding Orca Culture. 2011. Smithsonian.com. Smithsonian Institution. <https://www.smithsonianmag.com/science-nature/understanding-orca-culture-12494696/> Accessed 31 Mar 2020.

# data[].attributes.headline
The History of Killer Whales in Captivity

# data[].attributes.subject
The History of Killer Whales in Captivity

# data[].attributes.body
Because of their large size, high intelligence, and incredible athletic ability, orcas have become a favorite species of people everywhere. Certainly, this species was also catapulted to fame by their inclusion marine parks and shows, such as SeaWorld. However, recently concerns about the ethics and safety of these practices have emerged after a series of tragic events and the orca's poor living conditions were revealed to the public.

# data[].attributes.attachment_link.readable_text
SeaWorld has announced it is evolving its killer whale shows, which typically feature the orca Shamu, after activists repeatedly called them cruel.
Shamu is actually a brand name, based on the original star of these shows, who performed 50 years ago.

The first Shamu was captured in October 1965 and was purchased for SeaWorld in San Diego two months later.

She died in 1971 but lent her name to the many orcas who would follow, in shows that have become controversial.

Recently celebrities such as Harry Styles and Pamela Anderson have been campaigning against SeaWorld but in the past it wasn't frowned upon for them to pose with the orcas.

Peter Graves starred in the television series Mission Impossible and posed with a subsequent Shamu in 1975.

Kalina was the first orca to be successfully born and survive in captivity in 1985. Her parents Katina and Winston had been captured in the wild.

Kalina was known as Baby Shamu, although she was not directly descended from the original Shamu. She gave birth to a number of her own offspring, including this one in 1999.

Since then there have been Grandbaby Shamus and Great Grandbaby Shamus.

The first Great Great Grandbaby Shamu was born in 2014 and called Amaya.

Over the years, a number of trainers have had minor injuries and some have been seriously hurt, after altercations with the captive orcas.

The worst came in 2010, when Dawn Brancheau, who had many years of experience, was dragged by an orca called Tilikum into the water and died in front of Orlando park guests.

Park visitor Victoria Biniak said the whale "took off really fast, and then he came back around to the glass, jumped up, grabbed the trainer by the waist and started shaking her violently.

"The last thing we saw was her shoe floating."

SeaWorld has repeatedly updated its safety policies over the years and job applicants are told that the role is one of the "most rigorous" in the park.

Animal rights group Peta said it had long been asking SeaWorld to stop taking wild, ocean-going mammals and confining them to an area that, to them, is "the size of a bathtub".

Tilikum, the orca which killed Ms Biniak, was retired from performing for a while, but later returned to the park as one of its star turns.

He and other captive orcas were the subject of the 2013 documentary, Blackfish, which claims that they experience stress, increased aggression and a shorter lifespan by being kept in tanks.

This film spurred further campaigns against SeaWorld. The park has since called the film "propaganda".

In a statement on their website, SeaWorld says: "We object to Blackfish because its two central premises are wrong."

These are that "SeaWorld is harmful for killer whales and for trainers" and that they "attempted to cover up the facts surrounding the tragic death of trainer Dawn Brancheau" and Tilikum's role.

"Nothing could be further from the truth," they conclude.

Regulators in California approved SeaWorld plans to expand the orca habitat in San Diego, upsetting campaigners who want to see the animals released into the wild instead.

SeaWorld say the Blue World Project will give the public better access to viewing the orcas, while scientists will be able to better understand and care for them.

They say the habitat will have "more natural habitats" including water currents and shallow, beach-like areas.

The current San Diego show, One Ocean, will run throughout 2016, before being replaced.

In a statement, SeaWorld says: "The new experience will engage and inform guests by highlighting more of the species' natural behaviours.

"The show will include conservation messaging and tips guests can take home with them to make a difference for orcas in the wild."

While the public displays may be very different by 2017, this big investment suggests captivity will continue for some time to come.

Follow @BBCNewsbeat on Twitter, BBCNewsbeat on Instagram, Radio1Newsbeat on YouTube and you can now follow BBC_Newsbeat on Snapchat

# data[].attributes.attachment_link.title
The story of SeaWorld's Shamu killer whales

# data[].attributes.attachment_link.description
SeaWorld has announced it is evolving its killer whale shows, which typically feature the orca Shamu, after activists repeatedly called them cruel. Shamu is actually a brand name, based on the original star of these shows, who performed 50 years ago.

# data[].attributes.body
In 2013, the documentary Blackfish came out on Netflix and dramatically changed the way many people view SeaWorld and keeping killer whales in captivity. The documentary focuses on the history of SeaWorld's orcas, the practices SeaWorld uses to train and house its orcas, and several incidents between the animals and humans, some of which resulted in deaths of trainers. The program generated a firestorm of controversy in the media over the animals' welfare and incited a great deal of backlash against SeaWorld.

# data[].attributes.attachment_link.title
Blackfish Official Trailer #1 (2013) - Documentary Movie HD

# data[].attributes.body
Tilikum the killer whale is prominently featured in the documentary, as he was responsible for the deaths of two trainers and suspected in the death of another man who was thought to have illegally entered the park after hours to swim with the orcas. Blackfish portrayed Tilikum as being driven into madness by poor living conditions.

# data[].attributes.headline
However, not everyone agrees with the film.....

# data[].attributes.subject
However, not everyone agrees with the film.....

# data[].attributes.body
After the release of the film, former trainers spoke out against the film, saying that the trainers interviewed in the program were inexperienced and were not involved in any of the incidents they discussed. The documentary has also been accused of editing footage and audio to sway viewers, omitting important details about SeaWorld (such as their research and education programs), and and spreading misinformation about the incidents with the orcas and the park as a whole.

# data[].attributes.attachment_link.readable_text
SAN ANTONIO - Two former SeaWorld trainers involved in the controversial documentary "Blackfish" say the film is deceiving and includes speculation from inexperienced trainers who were not involved in the incidents they discussed.

The film, released last year, questions treatment of whales in captivity and the danger to trainers who perform with the whales.

Since it debuted, the park has endured public backlash. Eight performers, including Texas singer Willie Nelson, have canceled appearances, citing concerns about abuses depicted in the movie. Attendance, it seems, has not been affected.

Mark Simmons, a former senior trainer at SeaWorld Orlando who appears in the film, said the movie pushes a narrow viewpoint without providing balancing perspectives from more experienced trainers and sensationalized events to play to viewers' emotions.

"I was physically present during many of the events that (the trainers) talked about in the movie, and I can tell you firsthand they completely misrepresented, provided disinformation and in many cases blatantly lied about those events," said Simmons, who founded a marine mammal research and conservation organization in Orlando after working at SeaWorld from 1987 to '96.

Bridgette Pirtle, who worked at SeaWorld San Antonio from 2001 to '11, said the film was produced to make money, gain an audience and push an agenda to release all killer whales and shut down SeaWorld.

"It's not a fact-based movie," said Pirtle, who left SeaWorld in 2011 after the death of trainer Dawn Brancheau in Orlando, which is the central focus of the film.

"Yes, I'm still against animals as a form of entertainment, yes, I still believe that the breeding program should be ended," said Pirtle, 31. "But the goal of this film shouldn't have been to shut down SeaWorld, it was supposed to be an opportunity to improve the lives of the whales I dedicated my life to."

The film focuses on a killer whale named Tilikum, who killed Brancheau in 2010.

The documentary features in-depth interviews from four former trainers who provide perspective on the incident and operations at the waterpark.

Magnolia Pictures, the production company behind "Blackfish," declined multiple requests for comment. CNN, which produced the film and aired it nationally in October 2013, did not return multiple requests for comment.

SeaWorld said this week that it has had the best-ever attendance for the last quarter of 2013 and expects to report record full-year revenue of about $1.46 billion when the newly public company officially reports its fourth-quarter results in March, according to the Associated Press.

David Kirby, who authored "Death at SeaWorld," said the movie is accurate.

"I believe these allegations against the film are unfounded, and I don't know why they are being made but it certainly must be making SeaWorld very happy," said Kirby, whose research for his book was used in the movie.

Pirtle said she does not agree with SeaWorld that whales should be in captivity for entertainment purposes but that conservation, research and knowledge that stems from a limited number of animals in captivity is vital.

Simmons added that the social awareness that SeaWorld animals provide to visitors is important and leads to positive activism and education.

Pirtle, who's now a dance instructor in San Antonio, said she also is at odds with SeaWorld on the amount of money they invest in the whales' care, particularly because the orcas are the biggest money-maker for the theme park.

SeaWorld is one of the largest research and conservation organization for killer whales and other marine mammals.

Simmons said the director intentionally skirted details about that side of the industry to slant the movie.

There was no title or clear direction for the film when Simmons agreed to do an interview, he said.

Of the more than three hours of interview footage Simmons provided for the documentary, less than three minutes were used, even though he was the only trainer in the film who regularly worked with Tilikum.

Simmons said he asked for an advanced copy but the director, Gabriela Cowperthwaite, declined.

"When you watch the movie, I think it gives you the impression that this is a vastly dangerous environment to work in," said Simmons, 45. "My wife and I worked for a combined 18 years at SeaWorld, I've had thousands of interactions in the water with the whales, and neither one of us had a single injury caused by a whale."

Simmons said he had plenty of injuries during his tenure performing with the whales, from stitches to knee surgery, but none involved a whale. Simmons said his injuries came from slipping on the wet stage, ear infections from being in the water and back problems from carrying 40-pound buckets.

Pirtle, who did not appear in the film but was involved in its production, said the trainers featured in the film were inexperienced, have not worked at SeaWorld in more than a decade and have chips on their shoulders.

"My experience wasn't congruent with the direction of the film, which is now: 'Free the animals, SeaWorld is horrible, put the whales in a sea pen,'" Pirtle said, adding that the movie exploited Brancheau's death to make a profit.

For example, a 911 call at the beginning of the movie that features a first responder saying Tilikum swallowed Brancheau's arm, which is untrue, Simmons said. He said audio of whales feeding were portrayed to be the audio of young whales being separated from their mother.

Simmons and Pirtle, who spoke to the blog MiceChat last week, denied any communication with SeaWorld regarding their comments on the movie. Simmons said his zoological research company, Ocean Embassy, recently submitted a bid to SeaWorld for a zoological research database for the theme park but was denied.

Fred Jacobs, vice president of communications at SeaWorld, said the theme park has not been in communication with the trainers and confirmed the denied bid.

"We don't have any business association with Ocean Embassy," Jacobs said. "As Mark noted, another firm got the bid."

Pirtle said she hopes the film will encourage people to do their own research and to put energy into prevention of poaching and the collection of animals for entertainment.

"I think we are at a turning point right now where we can phase out using animals for entertainment. The whales that are there right now need to stay there. It is in the best interest of the animals, and it would be cruel to attempt to reintegrate them into the wild," said Pirtle. "But steps to perpetuate the cycle of having these animals in captivity need to stop. With the animals we do have in captivity, we need to switch gears, stop exploiting them for entertainment and use them for conservation, research and education."
kparker@express-news.net

# data[].attributes.attachment_link.title
Ex-SeaWorld trainers dispute 'Blackfish,' say phase out whale show

# data[].attributes.attachment_link.description
The film, released last year, questions treatment of whales in captivity and the danger to trainers who perform with the whales. Since it debuted, the park has endured public backlash. Mark Simmons, a former senior trainer at SeaWorld Orlando who appears in the film, said the movie pushes a narrow viewpoint without providing balancing perspectives from more experienced trainers and sensationalized events to play to viewers' emotions.

# data[].attributes.body
In response to the public's growing outcry against keeping killer whales in captivity, SeaWorld agreed to stop breeding whales for its programs. They also began to phase out their theatrical orca shows, instead replacing them with a more educational program  that still showed off the animals' talents.

# data[].attributes.attachment_link.readable_text
click to enlarge

Photo via Wikimedia Commons

With a new CEO at the helm, SeaWorld looks to be back on track with previously announced plans to phase out entertainment-driven animal shows. Its orca show, "One Ocean," is retiring at the end of December in both Orlando and San Antonio.

During the heat of SeaWorld's rough seas, former CEO Joel Manby made a splash in 2016 by announcing the end of orca breeding, and plans to phase out its theatrical orca shows. A year later, "Orca Encounter" debuted in San Diego in a newly remodeled orca theater that more closely resembled the natural Pacific Northwest where many orcas are found. The show opened to mixed reviews, but it was clear that this would be the future of the parks.

click to enlarge

Less than a year after the new show debuted, controversial CEO Joel Manby was out. Since then, the company has seen a revolving door of CEOs, with the most recent one, Sergio Rivera, coming aboard in November.

In the two and a half years since "Orca Encounter" debuted in San Diego, the company has been silent on what the future holds for its other two SeaWorld parks. But now with a new CEO in place, the plans to roll out the more educational presentations are now moving forward. An updated version of "Orca Encounter" will debut in Orlando on Jan. 1. In San Antonio, "One Ocean" will close Dec. 31 and "Orca Encounter" will debut when the park reopens in late February. Through Jan. 5, while the park wraps up its holiday openings, the short educational presentation "Killer Whales Up Close" will remain in the rotation, giving guests an opportunity to see the orcas.

For now, the stadium enhancements that San Diego saw won't happen in Orlando, where the new show will debut less than 24 hours after the final "One Ocean" show. It's expected that the Orlando and San Antonio shows will feature much of the same video content as the San Diego show, which focuses on orca biology and characteristics. Gone are the big musical numbers, emotional storyline, and trainers dancing to music. Instead, the orcas explore the tank as trainers talk about them. In between videos, trainers display many of the same tricks as the current show features, but now the tricks are presented in a more educational format that helps explain how they mimic natural tendencies of the orcas and why they're necessary to ensure the continued health of the animals.

Dr. Chris Dold, Chief Zoological Officer at SeaWorld Parks explained, "SeaWorld is excited about our new Killer Whale educational presentation, 'Orca Encounter.' Guests will learn about killer whales' role in the ocean ecosystem, behaviors the animals exhibit in the wild, the importance of conservation to their habitat, and animal welfare practices at SeaWorld. This educational presentation reflects our company's mission to inspire people and protect the animals and wild wonders of our world through education, research, animal rescue and conservation."

click to enlarge

The new show is a bit of a throwback to some of SeaWorld's earlier shows, before the spectacles they're now known for began. When "One Ocean," with its original soundtrack, debuted in 2011, it made history as the first show to remove trainers from the water with the orcas.

A year prior, trainer Dawn Brancheau was killed by an orca during a Dine with Shamu presentation. Surprisingly, both "One Ocean" and San Diego's version of "Orca Encounter" still feature trainers in close proximity to the orcas during the shows, including times where the trainers kiss the killer whales in a slide-out area near the front of the stadium.

While the educational show may appease some critics, SeaWorld still faces decades of criticism due to the use of captive orcas. Of the five orcas currently at SeaWorld Orlando, only one is above the age of 15 years old. Half of San Diego's ten orcas are 18 years old or younger. Two of San Antonio's orcas are less than ten years old.

According to the nonprofit whale advocacy group the Whale and Dolphin Conservation, in the wild male orcas can live up to 60 years, with an average lifespan of 30, while female orcas can live up to 90 years, with an average lifespan of 46. One female orca at SeaWorld Orlando, Katina, is currently 44 years old, while the oldest orca in SeaWorld's care is 54-year-old Corky II in San Diego.

Katina and Corky II are two of the three orcas still in SeaWorld's care that were wild-caught. Nearly four decades ago, the company pledged not to receive any wild-caught orcas. That pledge, along with the 2016 one to end breeding, means the current 20 orcas in SeaWorld's care will be the last ones that park, and likely the nation, will see. Online speculation that SeaWorld may introduce another "wow" animal to replace the orcas is also hamstrung by this pledge, since many of the more impressive species of sea life, like whale sharks, have yet to be successful breed in captivity.

click to enlarge

The new educational presentations are important, but some have pointed out that valid criticism of the tank size remains. Previous proposals to increase the size of the orca tanks, already some of the largest in the world, and provide "water treadmills" were quietly canceled, but the question remains what SeaWorld plans to do with the orcas in the long term.

Insiders have reported that trainers who work with the orcas are attempting to train the mostly captive breed whales how to catch live bait, which is preferred for multiple physical and mental health reasons. Much like a domesticated dog, the orcas in SeaWorld's care have lost many of their natural tendencies. It's also unclear how robust their immune systems are. These concerns have meant the theoretical sea pens that some advocate for may not be a possibility. But as animal welfare concerns become more mainstream, many animal facilities with large mammals are struggling to keep up with public expectations.

In recent years, wellbeing concerns for orcas have overshadowed those of many other animals, but there remains an increasing push for improved conditions for other animals, including elephants and dolphins. Some zoos, such as the Central Florida Zoo in Sanford, have phased out elephants altogether, replacing them with smaller, easier to care for animals. Many animal care facilities are also turning to new technology, like virtual reality, to shift how they tell the stories of these crucial species, but an orca-themed VR experience at SeaWorld San Diego received less than optimal reviews. As of now, there has been no indication that SeaWorld will offer the VR experience in Orlando.

The last significant new animal habitat at SeaWorld Orlando was the Manta aquariums in 2009, with the most recent animal habitat improvement being the Antarctica penguin exhibit in 2013. Since then, the company has focused on bringing non-animal attractions to the park, including the Mako coaster, the Sesame Street Land, and the upcoming Ice Breaker roller coaster. A similar thrill ride reliant growth strategy has been used at all of SeaWorld's other parks, including Busch Gardens Tampa and the other two SeaWorld-branded parks.

The company has also been quietly phasing out the Shamu branding, with the San Diego Shamu stadium being rebranded when it opened the new "Orca Encounter" show. Across all three SeaWorld parks, Dine with Shamu was

click to enlarge

replaced by a more generic Dine with Orcas branding. The Shamu Express kiddie coasters in Orlando and San Antonio were replaced by a Sesame Street theme in early 2019. They were the final Shamu-branded ride, though other references to the park chain's most famous orca remain.

Despite the shift away from Shamu, orcas remain a paramount part of SeaWorld's identity. In Orlando, the orca stadium still has a large Shamu Stadium sign and the park has a statue of orcas along its entrance on Central Florida Parkway. Nearby hotels have an orca-themed splash pad and bus stops in the area feature the park's iconic orca-tail design. Orca plushes are sold in gift shops throughout the tourist corridor and orca whale-tail ornaments hang from Christmas trees at SeaWorld. For the foreseeable future, orcas will remain a part of SeaWorld parks, for better or worse.

After the nearly universal approval of the orca retirement plan laid out by previous CEO Joel Manb in 2016, any backtracking would likely reignite controversies the company has mostly been able to settle. But with the orcas likely to remain around for decades, SeaWorld still has plenty to grapple with, from its past to how it shapes its future.

click to enlarge

Image via Stand with SeaWorld/Facebook

Stay on top of Orlando news and views. Sign up for our weekly Headlines newsletter.

# data[].attributes.attachment_link.title
SeaWorld Orlando is ending its theatrical orca shows, but they still have a long road ahead

# data[].attributes.attachment_link.description
click to enlarge Photo via Wikimedia Commons With a new CEO at the helm, SeaWorld looks to be back on track with previously announced plans to phase out entertainment-driven animal shows. Its orca show, "One Ocean," is retiring at the end of December in both Orlando and San Antonio.