Nowadays the demand of marine resources constantly grows. The growing demand stimulates the development of fishery and other marine resources exploitation. However, the unreasonable use of marine resources can cause the fatal damage to some ecosystems and to the global ecosystem of the world ocean. The over fishing is a main concern. The United Nations Food and Agriculture Organization, or FAO, provides the statistics about the global production from capture fisheries in the world. Within the recent two decades (starting from 1985) the reported landings of marine capture fisheries have fluctuated between 80 and 86 million tones per year (DKNVS report, 2006) However, the constantly increasing contribution of developing countries and China leads to the progressive growth of captive fisheries volume. At the same time, the overfishing in some regions has already led to ecosystem degradation and some species extinction. Analytics think that at the nearest future the fish will stay the increasingly high-value commodity, and the global demand to the fish and marine products will continue to grow.
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The usage of other marine resources, like energy resources, minerals, and gene pool, also grows and can lead to overuse and ecosystem degradation, too. In the aggregate the human exploitation of the marine resources and other factors of human influence, like the water pollutions and coastal agriculture, can lead to the irreversible changes in the ecosystem of the ocean up to the total degradation. Nowadays the technological potential of humankind doesn’t have the technologies of marine ecosystem resurrection.
The thesis of this paper the following: the human exploitation of the marine sources has to be controlled to prevent overfishing and other kinds of overuse, or the ecosystem of the global ocean can be irreparably damaged.
Human exploitations: earth vs sea
Humans are the link in the food chain so the human activity has an impact on ecosystems. Even early human societies changed the surrounding ecosystems. Nowadays the growth of human population and its impact on the environment escalated the problem on the global scale. Sure, the exploitation of the land resources is more active than the exploitation of the marine sources. There are many terrestrial ecosystems damaged and ruined with human factors. However, the lower speed of marine life cycle causes harder resurrection of the pelagic sources. The principal difference in the human exploitation on the land and on the sea is the following: on the land the humankind rebuilt the structure of terrestrial ecosystems and replaced the wild species with the domestic species. In the sea the important species weren’t replaced. They became extinct and the extinction of some marine species led to the degradation of marine ecosystems. Despite the existing fisheries regulations, the last majority of the fish stocks throughout the ocean are overfished. Not only fishes but marine animals like turtles and whales and some species suffer from population reduction up to 40% comparatively to the population volume a century ago. Some popular species are almost approaching extinction, for example, blue-fin tuna.
There are three types of overfishing, or three kinds of direct effects of captive overfishing. To make the maximal gain per recruit the fish should grow to the proper average size. The fishery of the smaller fish is a growth overfishing. To replenish the population it is needed the proper percent of mature adults. The shortage of mature adults in the population to the lower the level of reproductive capacity is a recruitment overfishing. The change in the balance of ecosystem caused by fishery and preventing the population growth is an ecosystem overfishing. All three types of overfishing have the negative impact on the ecosystem.
Thus, the exploitation of marine resources should be more careful and reasonable because of lower temp of resurrection.
Ecosystem effects of overfishing
Overfishing as a treat to biodiversity
There are also some indirect effects of overfishing, and the decrease in biodiversity is one of them. The loss in biodiversity is a serious treat to the ecosystem in a whole. “The cumulative loss of species-from inconspicuous worms to large fish-sharply reduces the ability of sea life to resist diseases, filter pollutants and rebound from stresses such as overfishing and climate change” (Blankenship, 2006) The numerous studies show that higher rate of biodiversity is the base of health and stability of ecosystem, as well as its ability to recover. However, the overfishing and the collapse of some the most popular species create the trend, which can lead to the total collapse of ocean ecosystem in 2048 (Blankenship, 2006). The careful fishery management can prevent the total collapse but the strict limits and bans should be implemented without delay.
The alternations in the food chains
Italian scientist Lorenzo Camerano outlined the dilemma of double-sided regulation in 1880 year. The dilemma is following: the high amount of birds can decrease the population of the insets in ecosystem, however, the number of birds can be high only on those regions were the large amount of food (mainly insects) is available. (Sheffer et al, 2005)This particular example illustrates the top-down and bottom-up mechanism of regulation in the ecosystem. The bottom-up regulation is the main mechanism of natural regulation and the marine ecosystems are no exception. However, the human interference is an important factor of top-down regulation, which changes the natural regulation in ecosystems including marine ones. The nature of food chain is similar in every ecosystem: solar energy and inorganic compounds are transformed by autotrophs, chemotrophs and litotrophs through photosynthesis and chemosynthesis to organic compounds. Then the organic compounds are transformed by heterotrophs into the more complex organic compounds. The predators are the highest link in the pyramid. Usually the number of predators is regulated by the number of low-level organisms. The disappearance of predators from the food chain can lead to the unrestrained growth of low-level organisms’ population.
The marine ecosystems have their specific features. The role of photosynthesis isn’t as significant as in terrestrial ecosystems. On the other hand, the majority of chemotrophic organisms inhabit the ocean. The primary producer in the marine ecosystem is phytoplankton and the fish is a main natural predator. Nowadays the top positions in the food web of all ecosystems are occupied with people. The overfishing, or the extinction the main natural fishing, can lead to trophic cascading effects changes in the ecosystems.
The recent example of trophic cascading effects caused by overfishing
The ecosystem of Canadian East Coast, hardly damaged with cod overfishing, suffers from the particular changes in the ecosystem. The east coast of Newfoundland was historically known as the region of fishery. The article in the Greenpeace archive tells that in 1497 year the explorer John Cabot wrote the huge cod school “virtually blocked his ship”. Five centuries after the Canadian government totally banned the fishery in this region because of the collapse of ecosystem.
After the decrease of large fish population following level of the food web – small fishes and large invertebrates, such as northern shrimp and northern snow crab – significantly increased the population volume. The growth on this food-web level caused the shortage on its nutritive base, large plant-eating zooplankton (> 2 mm). The decrease of zooplankton, in its turn, became the reason for phytoplankton population volume increase. The unexpected (but natural) consequence was the exponential increase in seal populations. The large fishes like cod compete with seals in the food web for the nutrition base. The extinction of main competitor allowed growing the seal population.
The economic consequences of cod overfishing were also significant. Thus, the cod stocks have started to recover in areas south of 44 degrees north. The strict bans can help to recover the cod population and to return the ecosystem to its initial state. However, other areas north of 44 degrees North the cod stock failed to recover despite a nearly complete shutdown of cod fishing. The coastal communities of Newfoundland still suffer from the job loss and struggle to recover.
The changes in marine ecosystem lead to the shift in commercial fishery to the low-level of food-web, smaller fishes and crabs. Nowadays the economic value of the shrimp and crab fisheries is more than the earlier value of the cod fishery.
Other indirect effects
There are also some other indirect effects of oversifishing that are not so visible, but they also contribute to the general problem.
The loss of macrofauna leads to the loss of ecosystem structure and the rise of “pests”. Generally pests are the species detrimental to humans. In the case of degraded marine ecosystems pests are the invasive species. With the lack of restrictive factors such species are able to congest the ecosystem and force out almost all native species declining the biodiversity. For example, European green crab, the native inhabitant of Baltic sea and the northern part of the Atlantic ocean, became the invasive specie in the seas of Australia, South Africa and South America.
The “ghost fishing” is effect from fishing nets lost of left in the ocean by fishermen. The nets are almost invisible in the dim underwater light. They can drift for a long distance. Fishes, marine animals, sea birds and even human divers can be caught and entangled with the net. The net restrict movement and can cause the disease, starvation and suffocation. The volume of “ghost fishing’ can hardly be evaluated because the most victims go down the ocean bottom.
Methods of overfishing prevention
The importance of fishery management increases simultaneously with the fishery development. The most popular methods of over fishing prevention are the implementation of fishing quotas, limits and bans, the development of fishing farms instead of captive fishery, the coastal zone management and some other measures.
Fishing quotas, limits and bans
Studies and analyses show that in the nearest future the sustainability concerns will increase due to environmental controversy. The growing demand will require the increase of fishery but the protection of marine ecosystems will require the strict bans, limits and control. The developed countries should implement the environmental regulations and institutions first and provide the same norms to the developing countries. The use of fishoil and feashmeal should become the important issue of the national policy. For example, China bans the fishery in the South China Sea for the certain period every year. However, all the quotas and limits cause the protests and resistance from fishermen.
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Fishing farms
The fishing farms are rather new but successful kind of fish production. “According to FAO statistics, the contribution of aquaculture to global supplies of fish, crustaceans and molluscs continues to grow, increasing from 3.9 percent of total production by weight in 1970 to 29.9 percent in 2002. Worldwide, the sector has grown at an average rate of 8.9 percent per year since 1970, compared with only 1.2 percent for capture fisheries and 2.8 percent for terrestrial farmed meat-production systems over the same period.” (DKNVS report, 2006) the shift to the fish farming from the captive fishing is rather slow. However, the fish farming can help to protect and even prevent the extinction of marine species. Thus, last year in Australia the first land farm of southern blue-fin tuna was established. The blue-fin tuna is very popular fish because of its buttery meat, for this reason this species is almost collapsed. The land farm fishing is a real fishing alternative and should be developed.
Coastal Zone Management
The Norwegian experience shows that coastal zone plans for every municipality can be very useful. These plans should designate the zones for tourism and recreation, for agriculture; for certain fishery related activities and protected zones. These plans should be revised within a certain number of years according the results of activities.
Other methods of fishing control
The pelagic stocks should be protected not only from overfishing but form the pollutions and the issue of global ocean environmental protection will receive more attention worldwide. The use of fish products in the terrestrial agriculture (like the use of fishoil as the nutritional supplement) should be reconsidered and reduced. Among the other measures of pelagic stocks protection should be the reduction and mitigation of the environmental impacts of intensive aquaculture. At last, the global institutions worldwide should develop the programs of poverty reduction on the seaside zones. It is necessary to reduce the volume of the captive fishery, both legal and illegal, and shift the fishery to fish farming.
Exploitation of other marine living resources
The overfishing is in the focus of this research; however, it is necessary to mention other kinds of marine resources exploitation. Besides the biomass resources like fish, plant and marine invertebrates, the marine resources include the raw resources (underwater deposits of oil, gas and minerals and the minerals dissolved in the sea water), the energy resources (thermal energy, wave energy, etc), and the gene pool. The development of underwater oil deposits (offshore drilling) started in the 19s century. For more than a century it became clear that offshore drilling changes the marine ecosystems in the region. The recent accident on the BP oil platform in the Caribbean Sea attracted the attention of global publicity to the problem of offshore drilling environmental impact and renewed the hot debates regarding the issue. The oil price growth stimulates the offshore drilling development, but the environmental damage of it overweighs the profits from oil trade in the long-term perspective.
The genetic potential of marine sources also attracts the attention to the marine sources. The biological and chemical diversity of the pelagic sources are well-known. Unique chemical compounds have a great potential for the cosmetic, pharmaceutics, and agrochemical industries.
The global ocean also hosts more than 300,000 species of plants and animals, and the scientists claim the majority of deep-water species is still undiscovered. Thus, the gene pool of marine biomass is a field of active research. The observations in Norwegian marine industries provide the information that “a relatively small number of marine plants, animals, and microbes have already yielded more than 12,000 novel chemicals. Some of the marine bioactive substances (with industrial applications as technological compounds, laboratory tools or ingredients in cosmetics) are already marketed and generate high benefits to mankind (and investors)” (DKNVS report, 2006).
Thus, the chemical compounds arabinosides extracted from the sponge, Tethya crypta, can be used in antiviral pharmacology and as the medicine in the acute myeloid leukemia treatment. It has a market potential up to $50 million annual sales.
The further research of the marine species and their potential will lead to the additional attention to the marine resources. However, the exploitation of any marine resource can be carefully managed and controlled to prevent the collapse of ocean ecosystem.
Summary and conclusion
The researches of marine resources discover new and new potential of its commercial use. The gene pool and the variety of chemical compounds in the ocean open new possibilities in pharmacology, industrial chemistry, cosmetics, etc. Modern technologies allow the development of offshore drilling and the underwater mining. However, the overuse of these possibilities can lead to the collapse of marine ecosystem. The example of overfishing shows the possible consequences of marine sources overuse. The fishery exists as long and humankind, thus its consequences are the most obvious and significant. The overshishing causes the decrease of diversity in ecosystems, the tropic cascading effects, and even the collapse of some species. It is the treatment to overall ecological unity of the ocean.
The fishery management can slowdown the ecosystem degradation and prevent the irreparable damage. The modern techniques of fishery management include fish quotas and bans, fish farming, coastal zone management and some other global management like the struggle with poverty in the coastal zones. The human factor already created the trend to the collapse of ocean ecosystem, and the immediate measurer are necessary to prevent it.
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