Indiscriminate fishing gear and unsustainable fishing practices unnecessarily and adversely affect the health of the marine environment by exacerbating the problem of over fishing and slowing or preventing the recovery of depleted fish stocks and other marine life. Massive numbers of unwanted species, juvenile or undersized individuals, and other marine wildlife are unintentionally caught and killed everyday. The resulting carnage is called "bycatch" or more appropriately "bykill.” Globally, the level of waste that is described by the term bycatch is staggering: more than 20 million metric tons (44,100,000,000 lb.) annually.
1 Roughly one-quarter of the annual global catch of marine fish, and more than four times the entire catch of U.S. fishers, is inadvertently killed and thrown back into the ocean as bycatch. To put this figure in perspective, the 44.1 billion pounds of marine life caught and discarded annually around the globe as bycatch is equivalent to the weight of 98,000 Statues of Liberty, or 60 Empire State buildings! This wholesale destruction of marine ecosystems has grave implications for the future health of the oceans. Ultimately, for animals caught as bycatch there are two possible outcomes: the animal either lives or dies. The unintentionally caught animal may be landed, in which case it is removed from the ecosystem, or it may be discarded. If discarded alive, there is no guarantee the animal will survive. Discarded animals which initially survive an encounter with fishing gear may die immediately afterwards or be weakened to the point where they are more vulnerable to disease or predation by other animals.
2 Depending on the species discarded and the type of fishing gear involved, survival rates can be as low as zero. Roughly 80% of the billfish discarded in the Gulf of Mexico and off the east coast of Florida by the U.S. commercial longline fishery die as a result of being caught and discarded.
3 Bycatch and dead discards can result in decreased levels of abundance, reduced spawning potential, and a diminished yield from fish stocks.
4 Over fishing and unsustainable fishing practices have depleted fish populations and destroyed fisheries around the globe. In recent years the worldwide catch of wild marine fish has stagnated at between 80 million and 85 million metric tons annually, despite large increases in fishing capacity. The reason: the seas are being stripped clean faster than they can replenish themselves. The Food and Agriculture Organization of the United Nations reported that by the early 1990s, 70 percent of the world's important commercial fish species were fully exploited, over exploited, depleted, or recovering from depletion. In the United States, more than 80 percent of marine fish populations that have been evaluated are classified as fully fished or overexploited.
5 What Is Bycatch?
In lay terms, bycatch is the unintended catch of animals associated with commercial fishing operations, the vast majority of which is discarded back into the ocean already dead or dying. Bycatch is pervasive the world's fisheries. It includes undersized or juvenile fish of targeted species as well as non-target species of fish, turtles, marine mammals, birds, and other wildlife. Bycatch is not inherent to all fishing efforts, it is the result of indiscriminate fishing gears, such as longlines and driftnets, and destructive fishing practices such as fishing in areas known to have large numbers of juvenile fish (nursery areas and spawning grounds).
Most damaging are non-selective gear types -- those that cannot target specific species of fish -- which catch and kill a huge volume and variety of marine species annually. Shrimp trawls around the world stand out as the fisheries with the highest bycatch and discard weight per landed target catch weight. However, high bycatch rates pervade most fisheries around the globe creating biological and economic waste of tremendous proportions.
The Hawaiian longline fishery for swordfish and tuna catches over 100,000 sharks annually as bycatch -- more than half are now killed as a result.
6 In 1996, the commercial U.S. Atlantic longline fishery discarded an estimated 40,000 dead juvenile swordfish because they were undersized.
7 In November 1996, the U.S. Northeast Atlantic drift gillnet fishery was closed on an emergency basis because of the threat it posed to endangered northern right whale populations. The fishery remains closed.
There are clean fisheries -- fisheries with low bycatch rates -- which use selective types of fishing gear or appropriate techniques. The Western Pacific pole and line fishery for tuna limits bycatch to less than one percent of total catch, and harpoon fisheries for swordfish and giant tunas have almost no recorded bycatch.
8 However, these fisheries are the exception rather than the rule. Bycatch associated with selective fishing gear generally consists of undersized or juvenile individuals of target species. Undersized or juvenile fish are often discarded either because of minimum size requirements or because the fish are not as economically valuable as their larger counter parts. Unfortunately, much of the bycatch ends up just as dead as the target species of fishes which are landed.
The solution is not to simply retain and use more of what is caught as bycatch, which would reduce waste, but do nothing to halt the emptying of the oceans. Rather, for species adversely affected by bycatch, such as sharks, sea turtles, whales, and other depleted species, the solution is to reduce bycatch rates and mortality by reducing encounters and increasing the survival rates of encountered wildlife, while managing fisheries based upon the biological imperatives of the most vulnerable species.