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Human use of ocean resources—past, present, and future In the past 

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Human use of ocean resources—past, present, and future In the past 

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There have been 200 years of resource exploitation in the Southern Ocean. From 1800 to 1840 the main catch was seal. After 1840, sealers were replaced by whalers, mainly because the seal populations had been virtually wiped out. Whales were caught mainly for their oil. In the next 100 years, the whale populations were reduced to a tiny percentage of their original numbers. Until the International Whaling Convention was set up in 1946, there were no controls on the number of whales caught. However, when the last whaling station in South Georgia was abandoned in 1954, it was because whale stocks had become so low that a profit could no longer be made, rather than as a result of the international regulations and the increasing public outcry against killing whales.

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The Southern Ocean consists of the southern parts of the Atlantic, Indian, and Pacific Oceans where they border Antarctica. Its cold waters are rich in life for three main reasons.

·      Cold-water holds dissolved gases such as carbon dioxide and oxygen better than warm water.
Nutrients and minerals are kept in suspension where they can bed try the phytoplankton because of the surface surface currents and regular storms that keep the sea surface rough.

·      During the long hours of daylight in summer there is almost constant photosynthesis, which allows a high yield of phytoplankton.

The phytoplankton is the basis of the food chain. The zooplankton in is ocean is dominated by the 5cm this long shrimp-like krill, which feeds on the phytoplankton. Krill often form dense swarms just below the surface, so dense on occasions that the ocean looks Pink. This means that the predators   higher up in the food chain can catch them with the minimum of effort. Krill are the major link in the Southern Ocean and Antarctic food chain, both as a direct and an indirect food supply.

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Marine pollution is a global problem: every country contributes to it. All the oceans are linked together and ocean currents transfer water between them. Therefore international organizations, such as the United Nations, must take the lead role to try to achieve international cooperation between governments. Organizations can only respond, however, once pollution has already taken place and the problem has been identified as serious. As early as 1982, dumping of radioactive waste at sea was banned worldwide. Locally, the United Nations Environment Programme (UNEP) coordinates programmes to tackle pollution in particular areas where several countries are involved, such as around the shores of the Black Sea. Although a large body of water, the Black Sea has only one narrow connection to the Mediterranean Sea. Two of Europe's largest rivers, the Danube and Dnieper, flow into it. These rivers carry and dump in pollutants from 9 different countries. The Black Sea has already suffered serious ecological damage from toxic chemicals, pathogens, phosphorus, and nitrogen. Eutrophication is taking place.

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Although environmentalists complain about increasing signs of pollution in the open ocean, many parts arc still relatively clean compared with coastal regions. This is because over 75 per cent of marine pollution comes from the land; the rest mainly comes from dumping by ships and from offshore mining and oil production. The impacts from some pollutants are immediate and easy to observe. Oil spills, for example, devastate marine life throughout the affected area. Other pollutants have longer-term and more sinister effects. It can take many years after exposure to radioactive isotopes for cancers to grow in humans to the point where they are life-threatening. Traces of metals accumulate in living organisms and gradually become more concentrated as they are passed up the food chain, until a point is reached where they begin to seriously affect sea birds and marine animals.

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Strategies for the harvesting of sustainable fisheries 

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Strategies for the harvesting of sustainable fisheries 

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At the United Nations Law of the Sea Conference in 1974, governments of coastal countries agreed to establish zones of 200 nautical miles around their shores. Within this zone a country has sole rights to all natural resources. This 200-mile wide zone is mown as an Economic Exclusion Zone (EEZ). Countries are responsible for marine resources in their own territorial waters.

The main way that countries manage fish stocks in their EEZs is through quotas. Annual limits are set for the amount and types of fish that can be caught. Once the quota limit has been reached, further fishing is forbidden; boats have to remain in harbor. Provided that scientific calculations of fish stock size are correct, existing stocks should recover to levels that will allow quotas to be increased in future years. To be effective the limits need to be policed both out at sea and in the ports where the fish is landed.

Quotas can be supported by other management policies. These include
• closed season for fishing, usually during the main breeding time during the year
• restricted areas with no fishing allowed so that breeding can take place and stocks recover
• limits on net types and sizes so that young fish can swim through the nets, leaving them time to grow to maturity and reproduce.

Peru now manages its fishing grounds better than it used to do. Nets are inspected and there is a 2-3 month closed season. Patrols are used to enforce the exclusion zone to keep out foreign vessels, especially Japanese.

Iceland refused to join the EU (European Union) so that it could keep full control over the management of the rich marine resources within its exclusion zone. Fish account for about 15 per cent-of Iceland's national income and tip .to 70 per cent by value of its exports. The quota to be caught by Icelandic fishermen each year is worked out as shown below.

• The Marine Research Institute, which is an independent scientific organization, estimates the size of the cod stock aged four years and above.
• Fishermen are allowed to catch 25 per cent.

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Consequences of Overfishing

Fish stocks on some fishing grounds are now at such low levels that for many year they will not recover the numbers needed for commercial fishing to begin again. All wild populations have their good times and bad; huge surpluses of fish that build up in years when food supply is plentiful are needed to ensure sufficient breeding stock for the lean years which will certainly come. Humans have regarded such surpluses as a gift of nature just waiting to be extracted and are now paying the price.

Hundreds of thousands of jobs in fishing and related industries were lost in the 1990s. Fishing boats were left rusting in ports, worth less than what owners paid for them. Small port communities, in remote locations where fishing is the only source of employment, have been badly hit. The desperate search for new fish supplies is spreading the problem of overfishing to other parts of the world, hitherto untouched,such as the Southern Ocean.

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Few have doubts about the main cause—use of new technology. There is comparison between old and new boats and methods of fishing. Luck no longer plays any part in finding great shoals of fish. Instead sophisticated fish-finding sonar and satellite navigation allow locations to be pinpointed with great accuracy. Once taken on board the modern factory ship, useful fish are sorted, gutted, filleted and frozen; their remains, along with the fish considered non-commercially useful, are thrown back into the sea. Working close to the home port is no longer essential.
In summary, today's modern boats are larger, can travel further, detect the whereabouts of the big shoals of fish with precision, and use nets so large that they scoop up everything in the sea including small and immature fish.
Despite falling stocks, fishing continues. Demand for fish continues to rise as the world population increases; fish shortages mean good prices for everything that is caught. Having invested a lot of money in boats and equipment, it is easy to understand why fishermen are desperate to stay in business and preserve their livelihoods. This is why some boat owners continue to overexploit fish stocks and use nets with too small a mesh size that trap immature fish.
Where a change in natural circumstances for the worse is combined with overfishing, the results are dire.

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Every major fishing ground in the world is now considered to be at risk; some have collapsed. It is estimated that 70 per cent of all world fish stocks have reached the point where commercial fishing is no longer sustainable. When European settlers first arrived in what is now Canada, they heard rumours that there were so many fish in the sea you could almost walk on them. Today on the Grand Banks off Newfoundland there are practically no fish. Overfishing has meant that there are insufficient fish left to carry on the reproductive cycle and raise stock levels to the point where large scale commercial fishing can return.
What has now become clear is that the number of fish caught should not be determined by the number of fish available, but by the numbers that will be left to maintain future fish stocks. Making money has been more important than leaving sufficient fish to grow to full size that will allow maximum levels of reproduction to be achieved.

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Fish are a major source of food, and in addition, an important source of protein, particularly in developing countries, where diets are often plant-based. Many jobs, both full-time and part-time, depend upon fishing. Apart from fishing itself, there is also work in related processing industries, such as canning, curing and farming for human use. Many of the smaller fish and other organisms, like krill, are processed in factories to make per food, animal feed, and fertilizers. In addition there are related industries, notably boat building, making nets and fishing tackle, and ice production.
There are wide variations in fish productivity in the world’s oceans. Traditional fishing grounds are located predominantly in the temperate zone of the northern hemisphere due to natural (physical) factors. The main factor is wide expanses of continental shelf--- off the cast coasts of North America and Asia, and off the west coast of Europe. These areas are naturally rich in plankton because of their shallow waters. However, the presence of mineral-transporting ocean currents (Labrador, North Atlantic Drift and Kurile) is also of great significance. Shoal fish such as herring, mackerel, cod and haddock prefer cooler temperate waters. In warmer tropical waters, the nutrient cycle does not function so effectively because a thermo layer occurs because of the lack of mixing between the warm surface waters and the cold deeps.
Human factors also help to explain the distribution of major fishing grounds. Many

Coastal regions in temperate areas are heavily populated fish has traditionally formed an important part of the diet, especially in Japan, and in Scandinavian countries like Norway and Denmark. Many boats work in the tropical water, between and around the islands of Indonesia; great quantities of fish arc eaten in many South-cast Asian countries as well, although a lot of the fish eaten in this part of the world comes from fresh-water sources and from fish farming.

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Movements of ocean currents are very complicated: they all vary in strength and change course from time to time. Undoubtedly the change that occurs off the coast of Peru, between the Peruvian and Southern Equatorial Currents about every 6 to 8 years, is the greatest. It has great human and environment till effects, which are not confined to South America and the pacific Ocean where it occurs
An EL Nino year in Peru

For reasons not fully understood, the south-east trade winds are weaker in some years. Warm water from Indonesia is allowed to drift eastwards across the Pacific. The usual pattern of flow of surface currents is reversed. This happens around Christmas off Peru, which is why Peruvian fishermen gave it the name 'El Nino', meaning the Christ child. This happens every 3-8 years.

The sudden change in seawater temperature has a dramatic effect on life both in the sea and on the land. Warm ocean water kills plankton and fish, because its currents are low in oxygen and nutrients. Beaches become littered with washed up dead fish and sea birds. The large fish shoals move further offshore into colder waters, out of range of fishermen with only small boats.

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• The Peruvian Current is supplied by cold water from the Antarctic Drift.
• Up-welling of cold water to the ocean surface takes place next to the coast of Peru.
• Surface, water off Peru is about 5tt cooler than expected.
• the current is rich in nitrates and nutrients.
• Higher up the food chain, great shoals of anchoveta fish arc supported.
• Large flocks of sea birds feed on the fish.
Economic importance of fish to Peru
• Anchoveta arc processed into fishmeal in factories in the coastal ports.
• Fishmeal is exported for animal feed.
• Earnings account for about 15 per (cm of Peru's exports is by value. )

• Many people work as fishermen and in the processing factories in the coastal towns.
• since it is a desert coast, other types of work scarce.
• Fish remains arc crushed and bird droppings (guano) arc collected for fertilizer.

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Ocean currents have direct effects upon the climate of adjacent coastal areas. Warm Ocean keep nearby coastal areas warmer in winter than they would otherwise be. Western European countries. such as the UK and Norway, should be very cold in winter, because they lie in high latitudes above 50'N. In fact, winters are mild because of the warming influence of the Gulf Stream and North Atlantic Drill. Outdoor activities can continue all year and less energy is consumed for heating, resulting in economic benefits.
The principal effect of a cold ocean current on climate is to reduce amounts of rain. Often that is a lot of mist and fog, but little actual rain. Compare the distribution of the world's dry areas with the places in the tropics where cold currents flow close to the coast. The world's driest desert in southern Peru and northern Chile is next to where the Peruvian current flows. In Africa, the Canaries and Benguela currents contribute to the formation of the Sahara and ‘Namib deserts. Economic activities on land (especially farming) are limited by a lack of rain, but offshore the cold currents greatly increase fishing opportunities.
One great economic advantage of ocean currents is that they support the world's richest fishing grounds. Currents carry nutrients. They are constantly being replenished to support great amounts of phytoplankton. In turn, at a higher level in the food chain, large fish stocks can exist. Ecologically, the richest areas occur where up-wellings of deep water happen, such as at continental margins, for example, off the coast of Peru and on the sides of oceans ridges, such as the mid-Atlantic ridge around Iceland .

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Distribution of ocean currents and their effects 

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Distribution of ocean currents and their effects 

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An ocean current is a great surface movement of water in a fairly well-defined direction. , The prevailing wind direction is the main influence upon its direction of flow. The friction between the wind and the surface causes 'drifts' of water. The shape and position of the landmasses influence the actual courses taken.
For example, look at the course followed by the Antarctic Drift on Figure 2.46. This current is pushed around the globe by north-westerly winds, the prevailing wind direction in temperate latitudes in the southern hemisphere. Unlike the other currents, it has no landmasses to interrupt flow. It simply drifts round and round the globe.
South of the equator, the circulation of currents in all three oceans (Pacific, Indian and Atlantic) is mainly anti-clockwise. This is because prevailing south-east trade winds in tropical latitudes push the West Australian, Benguela and Peruvian Currents northwards.
North of the equator current circulations arc mainly clockwise. The North Atlantic Drift flows towards Europe, driven by prevailing south-westerly winds, while north-east trade winds steer the Canaries Current back towards the equator.
Ocean currents are of two types, 'warm and 'cold'. This does not mean that the water in a warm ocean current is always warmer than that in a cold current. Warm and old are relative terms. In a warm ocean current, the water is warmer than would be expected at the latitude where it is flowing, because it is moving warm water from the tropics towards the poles. Cold ocean currents flow towards the equator; since they are moving water from colder areas of ocean, they are relatively cold bodies of water.

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Unfortunately during the past century, as the total human population on Earth increased, massively, not much thought was given to the world's oceans and was. People have removed billions of tonnes of living creatures from the sea, for most of the century, in the blind belief that this scars an inexhaustible resource. In exchange, they have added to the oceans billions of tonnes of toxic substances! Fish and other living things are looked on as commodities instead of important components of a living ecosystem. There needs to be more awareness that people need healthy oceans for a generally healthy Earth.

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Resources that people can use are concentrated on the continental shelf. This is the platform of level land no more than 200 meters under the ocean surface, between the low tide mark and the continental slope. Beyond are ocean deeps, about which much less is known because of problems of access.
The width of the continental shell varies greatly from place to place. It tends to be best developed along coasts fringing areas of lowland. Examples include
• off western Europe (it extends 320km from Land's End in south-west England) ...
• off north-eastern North America
• along the Arctic coast of Siherja (where it is up to I 200km wide).
Around other continents it is much narrower or almost completely absent, especially
along coasts where fold mountains run parallel and close to the sea, as along the borders of the eastern Pacific in both North and South America.
Fish is the most important ocean resource for humans. 'the world's most important fishing grounds are lotted on the continental shelves. More light can penetrate here than in deeper waters, and more oxygen is present. They arc also the most nutrient-rich puts of the oceans, with nutrients carried from the nearby land by rivers, which encourages an abundance of phytoplankton. . Oil and natural gas are examples of natural resources under the sea floor that arc exploited by people. Certain areas of shallow water, such as the Gulf in the Middle East,  the Gulf of Mexico, and the North Sea have hundreds of drilling platforms and rigs. These are commercially valuable resources because of the high world demand, for which the extra costs of operating in the sea, compared with on land, can be recovered. Within tropical waters, coral reefs attract tourists because of their natural beauty and teeming life of brightly coloured fish. Resorts in the Caribbean, around the Red Sea and Indian Ocean, and on the Great Barrier Reef in Australia attract visitors fascinated by divine and snorkeling possibilities among the reefs.

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Oceans occupy 70 percent of the Earth’s surface. Of all thee water on Earth, 97 percent is in the oceans. They exert a great influence over the planet’s weather and climate. They stabilise temperatures on land. More importantly, they yield moisture back into the atmosphere by evaporation, which replaces the Earth’s fresh water supplies in rivers and lakes so that all of us can use it. In the life-filled oceans, oxygen is generated and carbon dioxide absorbed. Without the ocean, earth would be a lot like mars— a place unsuitable for humans and the rest of life on earth, as we know it.

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The primary producers, upon which all the other ocean life depends, are the phytoplankton simple single-called organisms of the sea. They only exist in the upper layers of water because they depend upon sunlight and for the production of organic matter through the process of photosynthesis. Of the 100 percent of energy available from the phytoplankton only about 2 percent is left from the fish layer and potentially available for human use, the rest has been lost to respiration and water. The key feature in all ecosystems is interdependence: each part of the chain depends upon another. For example, what would be the knock-on effects in the food chain of a decrease in availability of nutrients in one part of the ocean?