HSIAsia >>Marine Mammals >>

Commercial Fisheries and Marine Mammals

The United State Government estimates that as many as 100,000 marine mammals are killed or injured by the U.S. commercial fishing industry each year. These deaths and injuries result from boat collisions, entanglements in fishing gear, and entrapments as nontarget species (often called bycatch). Many more marine mammals are killed, injured, and harassed by foreign fleets, most infamously by the tuna fleets in the Eastern Tropical Pacific (ETP), despite large-scale efforts by environmental and animal protection groups to change fishing practices in the area. Because spotted and spinner dolphins associate closely with yellowfin tuna in the ETP, the nets used to capture the tuna encircle, traumatize, and may entangle and kill these dolphins.

Drift-netting, a practice that has yet to be completely outlawed internationally, is a deadly threat. Made of fine nylon mesh, drift nets can be miles long and many feet deep. The nets are left adrift for days and even weeks before fishing boats return to check their catch. These nets catch everything in their paths, including mammals, birds, turtles, and sharks. Many of these victims are considered worthless bycatch and are discarded. Drift nets are the indiscriminate stripminers of the seas.

Fisheries pose another danger, for they may compete with marine mammals for the same fish and in the process reduce fish populations that marine mammals depend on for food. Fisheries in many regions have cut their fleet sizes because they have overfished populations, and some have had to close because fish stocks have become commercially extinct, too small for continued commercial exploitation.

The loss of these fish populations has a negative effect on the marine ecosystem. For example, the decimation of the Steller sea lion population in the north Pacific is attributed to the collapse of fish stocks the sea lions have depended on, stocks that were overfished by certain Alaskan fisheries. Marine mammals cannot survive without a plentiful food supply, so overfishing by fisheries presents a real danger to the health of the marine ecosystem, especially when marine environments are also beset by pollution and other forms of habitat degradation.

Recreational fishermen claim seals and sea lions are threatening their livelihoods by following charter vessels out to sea and taking fish from sportfishermen's lines. While it is true that some seals and sea lions have taken advantage of foraging opportunities provided by commercial and recreational fishing boats and dams and locks at the entrance to fish spawning rivers, there are non-lethal solutions to these interaction problems. In addition, the real cause of declining fish stocks is not growing seal and sea lion populations but the growing human population. Too many people are moving to the coast and contributing to unsustainable habitat degradation and exploitation of resources.

Fisheries Factsheet

The United Nations' Food and Agriculture Organization (FAO) has estimated that 950 million people worldwide rely on fish and shellfish for more than one-third of their animal protein. Over 200 million people depend upon fish as a main source of income, particularly subsistence fishers in developing countries. The Humane Society of Asia recognizes the significant international dependence on fishing as an industry. Our primary concerns are the gross over-exploitation of fish populations, the impact of commercial fishing activities on other, non-target marine creatures, and the growing tendency of governments and industry to blame marine mammal predation for fish stock depletion.

Fisheries Over-Exploitation

Since the 1970s, fisheries have skyrocketed to unprecedented levels of production. The FAO estimates that 70% of the world's fish species are either fully exploited or depleted. The worldwide fleet of commercial fishing vessels has doubled since 1970 and operates at a loss of 54 billion taxpayer dollars every year. The annual global catch peaked in 1989 at 89 million tons and has currently stabilized at about 85 million tons. This abuse has raised great concern within all areas of the fishing community.

In the past, the world's oceans represented an international common ground and were essentially unregulated. The urgency of over-exploitation problems, however, has escalated localized disputes into international conflicts. Exclusive Economic Zones have been established along coastal borders to restrict foreign fishing, extending up to 200 nautical miles from a nation's shores, and are often forcefully defended.

Additional Depletion Factors

There are other factors contributing to the decline of the global fish population. As much as one-fourth of the annual catch is lost to spoilage or discarded as bycatch (fish that are under-sized or species of little or no commercial value to a particular fishery, although fish discarded as bycatch in one fishery may be the target species for another). Nets lost at sea continue to catch and kill fish and other marine life. Some fishers use potentially dangerous methods such as dynamite or cyanide to bring fish to the surface, which can heavily damage or destroy ecosystems such as coral reefs.

About 80% of marine pollution is land based. Coastal development has caused environmental degradation of marine ecosystems, including fragile coastal nursery areas used by open-ocean species, with increased erosion, sewage, toxic chemicals, and industrial pollution in rivers. Activities including dredging, oil drilling (and spills), pipe laying, and waste dumping all endanger fish habitats. It is predicted that global warming will slowly raise ocean temperatures. Increased ultraviolet radiation from ozone depletion threatens many species. Nuclear pollution in parts of the world also harms marine life. In addition, human introduction of exotic species threatens native populations.

Risk to Non-Target Species (Bycatch)

As a conservative estimate, more than 30 million tons of marine mammals, sea turtles, seabirds, sharks, and other unwanted fish are thrown back into the oceans, dead or dying, annually. The actual number is almost certainly far higher. Methods used by large-scale fisheries often prove deadly to the many other marine creatures who share their home with commercially targeted fish species. Some fisheries use large nets with small mesh, trapping or fatally wounding many non-target species. Other gear with high bycatch rates include "longlines" and "bottom trawls." One of the worst fishing methods is drift-netting; a drift-net may be miles long, with an all-but-invisible plastic mesh that ensnares everything in its path.