Saturday, July 01, 2006


original posting: 25 feb. 2002


Ecosystems: Overfishing, Bycatch, and Destructive Fishing

(02/16/2002) Record 1,337 endangered sea turtles died on Florida beaches in 2001, most after drowning in shrimp nets or hit by boat propellers and hulls. See Endangered Species: Sea Turtles.

(02/16/2002) Scientists warn current rate of overfishing in the North Atlantic will result in an ocean-wide collapse within 10 years, leaving nothing but jellyfish and plankton. The entire North Atlantic is being so severely overfished that it may completely collapse by 2010, according to scientists who have just completed the first comprehensive assessment of fish stocks in the North Atlantic Ocean. If current overfishing continues in the North Atlantic, trawlers could soon be left chasing jellyfish and even plankton to make "fake" fish products. "We'll all be eating jellyfish sandwiches," says Reg Watson, a fisheries scientist at the University of British Columbia who participated in the study.

While the disastrous collapses in areas like New England and Newfoundland have appeared to be local in scale, the new ocean wide synthesis reveals that the collapse applies to the entire North Atlantic Ocean. The study shows that across the region as a whole, the North Atlantic now has only about one-sixth the number of high-quality "table fish" like cod and tuna that it had in 1900 and is being fished eight times as intensively, scientists say. Fishermen are also chasing species ever lower on the food chain as bigger fish are depleted.

"We have looked at the entire North Atlantic - Canada, USA, Europe - and what we have found is that the situation in the region is far worse than people had anticipated," project leader Dr. Daniel Pauly, from the University of British Columbia, Vancouver, Canada, said.

"With few exceptions, we are going to lose most fisheries in the next decade if we don't quickly mend our ways," said Pauly. "It may sound like a doomsday scenario, but the decline is actually accelerating. Even where stocks are doing better, they are still hovering at the bottom of a pit."

"The jellyfish sandwich is not a metaphor - jellyfish is being exported from the US," says Pauly. "In the Gulf of Maine people were catching cod a few decades ago. Now they're catching sea cucumber. By earlier standards, these things are repulsive."

The group of 10 scientists and about 50 consultants undertook the 2-1/2 year analysis after becoming frustrated by the lack of any oceanwide fisheries information. The group is composed of fishery scientists, biologists, and economists from research institutions in Europe and North America.

Most researchers and regulators tend to focus on only one species or geographical area and little of the information has been pieced together. The scientists, however, did just that, synthesizing millions of numbers regarding fish species, catches, and populations over generations to come up with a model of the North Atlantic.

The researchers divided the North Atlantic into 22,000 grid cells, each measuring �� of latitude by �� of longitude. Data from the past century were then painstakingly "retrofitted" on to this grid in order to calculate each cell's biomass of high-value "table fish" (ie, species preferred by humans, such as cod, haddock and halibut). The biomass in each cell was reconstructed using a mathematical model that distributes individual species according to known environmental and physical variables, and also historical records of what fish were caught where and when. Then the researchers were able to calculate the fishing intensity as the ratio of the catch data to this biomass.

The result is a clear picture of how fishing expanded from the coasts of North America and Western Europe, pushing out farther and farther into the ocean - something known as serial depletion. This continued until catches peaked in 1975, after which the catch began to decline. Dr. Villy Christensen estimates that over the past century the intensity of fishing in the North Atlantic has increased eightfold, while the biomass of table fish has fallen by 85%.

Watson, who helped produce the study, said the crisis is evident in the collapse in catches. "If you look at those prime table-fish - the ones we value the most, the fin fish - in the 1960s, we had about 21 lbs (9 kg) per person, now we're down to a third of that; we're down to about 7 lbs (3 kg) per person. If you extrapolate that very straight linear trend, within 10 years we'll be talking about fish as if they were a myth; as if they were fond memories," said Watson.

In the last 50 years, the catch of popular fish species such as cod, tuna, and haddock has decreased by more than half despite a tripling in fishing across the North Atlantic, the study found. It is not just that there are more boats; sophisticated technology also makes the fish easier to catch. Countries spend $2.5 billion in taxpayer's money each year to "search out the last fish left" in the North Atlantic, said Rashid Sumaila of the Michelsen Institute in Norway, who conducted an economic analysis as part of the study.

At the same time, fish gets more expensive every year, Sumaila noted. U.S. seafood prices, especially for lobsters and shrimp, have increased 20-fold since 1950. New Englanders can continue to eat their favorite fish because much of the seafood is imported from developing countries, a practice that the scientists said should not be allowed to continue.

The spiraling costs also include the price of fuel. Fishers burn more and more fuel as they increase their efforts competing to capture the last of the dwindling resources. "The fuel energy needed to capture a ton of fish has doubled over the last twenty years," says Peter Tyedmers of Dalhousie University.

Faced with dwindling stocks and rising demand for seafood, fishers are employing new technologies that leave no safe haven for fish, including the application of military technologies, spotter planes and round the clock exploitation. For most of human history, fish and other marine species had naturally protected areas: places inaccessible to fishing because they were too remote, too deep or too dangerous to fish. But civilian applications of military technologies, such as those developed for submarine warfare and espionage, have grown by leaps and bounds since the end of the cold war. These transferred technologies include sonar mapping systems that reveal every crack and contour of the seabed in exquisite detail.

The U.S. Geological Survey is now publishing maps that are enabling fishers to penetrate deep into regions once considered too difficult to fish. Private companies are also weighing in, selling the secrets of the seabed for short term profit. Guided by precision satellite navigation systems, fishers can now drop nets into previously unseen canyons, or land hooks on formerly uncharted seamounts.

"Such places may be the last refuges of vulnerable species like skates or rockfish," warned Dr. Callum Roberts, a Harvard University ocean ecologist...

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