One-quarter (25%) of all the fish pulled from the sea never make it to market. The UN's Food and Agriculture Organization (FAO) reports that, on average, 27 million tons of unwanted fish catch are thrown back each year. Most do not survive (FAO's estimated range of bycatch/discards is 17-39 million tons/yr, but does not include marine mammals, sea birds and some invertebrates killed in fishing operations). Twenty seven million tons represent more than half of all fish produced annually from marine capture fisheries for direct human consumption.
Bycatch is the marine life caught during fishing even though it is not being targeted. Most bycatch include non-target or low-value species, but vast tonnage of undersized fish of valuable commercial species are also involved. Sometimes bycatch fish are kept for market, but most often they are thrown back dead, because they may be the wrong species, the wrong size (usually too small but sometimes too big), of inferior quality, or surplus to the fishing operation's quotas.
Recent research from Alaska, for instance, suggests that Bering Sea red king crab discards amounted to about 16 million animals in 1990, more than five times the number actually landed for market. It is not known how many of these discarded crab (many of them immature crabs) survive after they have been thrown back into the sea.
Almost 350 million kilograms/350,000 tons) of fish were caught and then thrown back by Alaskan fishing boats in 1993 because they weren't the kind of fish or the size that the boats were trying to catch. In the Gulf of Alaska's pollock fishery discards nearly equal the actual catch in some areas.
In the North Sea, about half of the haddock and whiting caught for human consumption is discarded every year. Eighty million cod may have been discarded in the cod fishery off the northern coast of Norway in the 1986-1987 season because they were too small to market.
Shrimp Trawling: the King of Wasteful Fishing
It is the massive waste of commercial trawling for shrimp and prawns -- particularly those operating in tropical waters -- that tops the list of waste and destruction. An estimated 11 million tons of finfish are discarded each year in shrimp trawl fisheries. It is common for 90 per cent of a shrimp trawl to be made up of bycatch finfish, with only ten percent shrimp. In some shrimp trawl fisheries, for example the Trinidad shrimp fishery, almost 15 tons of fish are discarded for every ton of shrimp landed. The fish are either dead, dying, or likely to be consumed in its weakened state by predators.
Shrimp trawlers in the Australian northern prawn fishery discard some one-and-a-half tons or 70,000 individual animals each night. More than 240 species, including 75 families of fish, 11 of shark, and several of crustaceans and molluscs have been identified in the dumping of some 30,000 tons of marine life.
In the U.S. Gulf of Mexico shrimp trawl fishery 115 different species of finfish are taken along with shrimp -- many of them the immature, juvenile fish of other commercially valuable species. In 1986 and 1987 an estimated two billion kilograms of Gulf of Mexico finfish were dumped overboard. Studies on the impacts of shrimp fishery discards on finfish species and turtles in the Gulf reveal declines in the population levels. The impacts of discarding
Bycatch removes fish that would be better left in the sea alive as part of the intricate food web. In many cases bycatch consists of the young, immature fish of commercially valuable species. They could otherwise replenish the stocks if allowed to mature. Much of discarded bycatch consists of non-commercial species of fish which are an important food (prey) for other commercially targeted fish, endangered species of fish, or other marine wildlife such as seabirds.
There are potential knock-on effects of bycatch, not just for commercial fish stocks, but the entire assemblage of species in marine ecosystems generally. For example, discard mortalities are known to have contributed to changes in the abundance and relationships of species in the Gulf of Alaska. These effects are so complex and the data often so inadequate that scientists can do little more than highlight how enormous the problem is.
Added to the massive fish discard figures and the bycatch of other marine animals are unknown quantities of marine life killed or harmed in fishing operations without ever being brought on board. They include loss of species from gear while fishing. Species which may escape fishing gear while still in the water do not escape unharmed, weakening their chances of survival after escape.
The waste and damage caused through the use of unselective fishing gear and indiscriminate practices must be eliminated. In 1995, the UN's FAO fisheries department estimated that a 60 percent reduction in discards by the year 2000 could be achieved. Unfortunately, most governments have been reluctant to impose strict regulations to reduce discards.
Beyond requiring the development and use of selective gear, the most important step governments can take is to reduce the total fishing effort as low as possible. Excessive fishing effort only results in an increased risk of irreversible harm, and not in a long-term increase in catch, regardless of how selective the fishing gear itself may be. Developing selective technologies, better regulations and stronger enforcement can help, but wasteful discards are tied in large part to the problem of too many boats doing too much fishing.