Overfishing, a major threat to the global marine ecology

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Temps de lecture : 3 minutes  


Today’s fishing technology is highly elaborate. Fishing lines can reach as much as 120 km, furnished with thousands of hooks. Some trawlers reach 170 metres in length and can take on board the volume equivalent of 12 jumbo jets, and drift-nets can exceed 60 km in length. Fishing vessels cover large distances at high speed, from coastal zone to high seas. They fish at great depth, stay at sea for several months, while fish are often prepared for the markets on board. Destructive sea-bed habitat bottom trawling involves powerful boats dragging heavy, metal weighed nets across the ocean floor to catch the maximum possible amount of bottom-dwelling life. Each year, bottom trawlers drag an area twice the size of the continental United –States! Sonars, air monitoring systems and satellite platforms help to locate fish schools and follow them with greater ease. Navigation apparatuses, such as Global Positioning System (GPS) and radar allow boat to constantly reconsider the best fishing spot, with very high precision. Fresh fish is a highly perishable product and its consumption was traditionally limited to coastal areas. With modern transport and food preservation technologies, one can offer fresh fish during all seasons, anywhere in the world.

Open access and over-capacity

Over- capacity is the presence of too many vessels in a growing number of fisheries. Fish stocks have generally been considered common property, open to the exploitation by anyone with a boat and gear as long as they were used outside a country’s 200 Mile Exclusive Economic Zone. If enough fish are caught to cover operating costs, there is little economic incentive to stop fishing once a vessel is built. As more fishermen enter the system, greater effort is required to catch a dwindling supply and revenues fall. In time, fish stocks can be severely depleted. Excessive fishing capacity leads to overfishing and therefore to the degradation of fishery resources. Such unsustainable practices, creating a conflict between short-term and long-term gains, lead to serious impact on biodiversity and diminish vital food production potential for a number of developing countries.


The word “bycatch” refers to the portion of marine life caught that was not targeted. It may include low-value species but also vast tonnage of young or undersized fish of valuable commercial species. Almost 25% of all the fish pulled from the sea never make it to the market. An average of 27 million tonnes of unwanted fish are thrown back each year, and a large portion does not survive. Sometimes bycatch fish are thrown back dead, because they may be the wrong species, the wrong size, of inferior quality, or surplus to the fishing operations quotas. The potential effects on bycatch are not just for commercial fish stocks but the entire diversity of species in marine ecosystems and essential food chain components. Bottom trawling nets are indiscriminate and tend to pick up everything in their path with an extremely high bycatch rate. For example, up to 95% of the take in halibut trawling can be bycatch, which include a variety of endangered or overfished species.

Subsidies and job

Large economic losses have plagued the global fisheries sector for more than a decade. However, national governments have traditionally heavily subsidised the fishing industry, since it is an important source of employment, food and export earnings. Such subsidies have often been used with little consideration for their long-term damage to natural resources. Global subsidies, which reach about US$ 13 billion per year, encourage fishermen to remain in a depleted fishery even though it may no longer be profitable, thus further depleting marine resources. About 50 million people( including 35 million fishermen) worldwide depend directly on fishing for their living. According to the FAO, reducing the large -and medium- scale fishing industry by half might eliminate several hundreds of thousands jobs. Reducing the small scale, artisan-fishing sector by half would eliminate several million jobs.

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