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Small fry have big effect: overfishing threatens a critical link in the food chain.

THE FISH near the bottom of the aquatic food chain often are overlooked, but they are vital to healthy oceans and estuaries. Collectively known as forage fish, these species --including sardines, anchovies, herrings, and shrimp-like crustaceans called krill--feed on plankton and become food themselves for larger fish, seabirds, and marine mammals. Historically, people have eaten many of these fish, too, of course, but as demand for animal protein has soared over the last half-century, more and more forage fish have been caught to feed livestock and farmed fish instead of being eaten by people directly. A growing body of scientific evidence suggests that current fishing levels are dangerously high--for the forage fish themselves as well as the predators and industries that depend on them.

Found from the tropics to the poles, forage fish typically travel in dense schools of thousands or even millions, which makes them easy prey for modern fishing fleets equipped with purse seine nets that can cinch up an entire school at once. What is more, forage fish stocks are highly sensitive to environmental change and prone to population crashes, so fishing levels considered safe in good years can be disastrous in bad ones.

Many of the world's largest fisheries focus on forage species, including Peruvian anchovy, Atlantic herring, and chub mackerel. Together, forage fish typically account for more than 30% of the 80,000,000 tons of fish caught annually in the world's oceans and estuaries. Roughly nine of every 10 tons of forage fish hauled in are destined for the "reduction" factory, where they are cooked and pressed to extract the oil; what remains then is dried and milled into fishmeal, a high-protein brownish powder. About 6,000,000 tons of fishmeal and 1,000,000 tons of fish oil are produced each year. Nearly all of the fishmeal is fed to farmed fish, pigs, and poultry. The oil, high in omega-3 fatty acids that are prized for their health benefits, is a popular feed additive and also is employed as a nutritional supplement for humans.

Notwithstanding their large contribution to the world fish catch, forage fish are worth at least twice as much in the ocean as they are on the boat. In 2012, the Lenfest Forage Fish Task Force, an international group of 13 marine and fisheries scientists, released the results of a three-year study, "Little Fish, Big Impact." The authors calculated that forage fish generate nearly $17,000,000,000 per year in reported catch-$5,600,000,000 for the small fish themselves and $11,300,000,000 in landings of the fish that eat them. This does not include the value of ecotourism for watching whales, which eat forage fish; the value of recreational sport fishing where forage fish are used as bait; of the important role of forage fish in keeping plankton under control.

Forage fish have a long history of being targeted for meal and oil. For example, Atlantic menhaden--herring and sardine relatives that migrate along the U.S. Atlantic Coast--were first sent to processing factories in New England and the mid-Atlantic region in the mid 1800s to become fertilizer and a cheap substitute for whale oil, which was used in everything from leather tanning to cosmetics. Menhaden meal later was used in animal feed, beginning in the early 1900s. (Around that time, northern Europeans started fishing Atlantic herring for the same purpose.) Still used mainly in feed--but also in health supplements--Atlantic menhaden are one of the largest U.S. fisheries by weight today.

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As more pork and poultry producers in the U.S. and Europe began using inexpensive fish-meal in feed rations, landings of forage fish grew. When the large-scale Peruvian anchovy fishery was launched in the 1950s and Peru and Chile aggressively began to exploit the productive waters along the western coast of South America, fishmeal use in feed began to spread worldwide. For decades now, the Peruvian anchovy has been not just the world's largest source of fishmeal, but the world's largest fishery overall, in some years topping 10,000,000 tons. Peru alone has some 1,200 vessels supplying anchovy to 140 reduction factories, which produce meal and oil worth about $2,000,000,-000 per year in exports.

While the Peruvian anchovy fishery indeed is lucrative, it also is, like many other forage fisheries, highly dependent on favorable environmental conditions. Especially during El Nino events, warm Pacific Ocean waters---sometimes with overfishing as an accomplice--have, over the decades, led to numerous anchovy population crashes and devastated harvests. In October 2012, Peru cut the allowed anchovy catch to its lowest level in 25 years after the fish's population plummeted yet again, likely due to warmer ocean temperatures. With the anchovy supply thus restricted, the world price of fishmeal jumped to a record high by December.

A half-century earlier, the young but already massive Peruvian anchovy fishery illustrated the ecological repercussions of heavy forage fishing. Unfavorably warm waters and an anchovy catch averaging 8,000,000 tons per year depleted the food base for cormorants, gannets, and pelicans in the mid 1960s. Severe population declines among these birds ensued. Cormorants, almost entirely reliant on anchovies for food, saw an 89% drop from their historical average. Seabird populations in this ecosystem still have not recovered.

Worldwide, three-quarters of the 72 marine ecosystems studied by the Lenfest Task Force contain predators dependent on forage fish for at least half their diet. Some predators--including the blue whale, Humboldt penguin, and yellow-fin tuna--rely on forage fish for at least 75% of their diets. For these animals, plummeting prey populations can mean both impaired breeding and starvation.

The vast majority of the world's forage fish stocks either are considered exploited fully, with no room for safely increasing the catch, or they already are overfished and in need of rebuilding. Given the climate sensitivity of forage fish and the key ecological role they play, the Lenfest authors recommend that, in general, catches should be half of their current levels.

Reducing demand for fishmeal and oil largely will depend on the aquaculture sector. Twenty-five years ago, pigs and poultry accounted for 80% of world fishmeal consumption. By 2000, this share had dropped to 60%. However, over the next decade, aquaculture production doubled, fishmeal prices rose nearly fourfold, and pig and poultry producers rapidly replaced fishmeal in feed with soybean meal. Today 68% of fishmeal goes to fish farms, as does 74% of fish oil.

There are some encouraging signs on this front, however. For example, nearly every major type of farmed fish--from salmon to carp--has seen significant reductions in the fishmeal content of feed since the mid 1990s as proteins from plants (particularly soybeans) and livestock and poultry by-products increasingly have become suitable alternatives. Between 1995-2007, the fishmeal content in shrimp feed dropped from 28% to 18%. The drop was even more dramatic for salmon, from 45% to 24%. The recent surge in fishmeal prices is forcing additional feed switching.

There also has been a rise in the use of seafood industry by-products in fish feed. In 2010, one-third of fishmeal production came from fish trimmings and other food fish production wastes. On the other hand, finding substitutes for fish oil rich in omega-3s has been mole difficult and may prove a bigger obstacle to lowering the forage fish catch in line with scientific advice.

Some scientists and chefs have promoted greater consumption of forage fish directly as food, noting that this is much more efficient--and more accessible to poorer consumers--than eating them indirectly through farm-raised salmon or shrimp. Forage fish already provide an important protein source in many low-in-come countries around the world, especially in coastal Africa. In fact, they account for more than hall the supply of food fish in 36 countries, including the Maldives, the Philippines, and Ghana. Direct consumption, too, is on the rise in some countries. For instance, Peruvians ate 190,000 tons of anchovies in 2010--19 times as much as in 2006.

With the global fish catch no longer expanding, aquaculture will continue to satisfy the growth in worldwide demand for fish-based protein. Indeed, fish farming output is expected to increase 33% by 2021. What remains to be seen is whether the move away from fishmeal and fish oil in feed, along with a move toward precautionary management, can occur on a large enough scale to protect forage fish--and the people and ecosystems they support--adequately in the future.

J. Matthew Roney is a research associate at Earth Policy Institute, Washington, D.C.
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Title Annotation:Ecology
Author:Roney, J. Matthew
Publication:USA Today (Magazine)
Geographic Code:1USA
Date:May 1, 2013
Words:1417
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