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Monday, August 13, 2007

Innovative Tagging Technique and Better Protect Fish Stocks

Marine Protected Areas (MPAs) are often hailed as a way to halt serious declines in the abundance of marine species that have been over-fished. But even as nations begin to set aside protected parcels of ocean for marine reserves, the effectiveness of the approach as a fisheries management tool remains unclear. Simon Thorrold, a fish ecologist from the Woods Hole Oceanographic Institution (WHOI), would like to put MPAs to the test with a novel technique for tagging fish.
Through a new research grant from the David and Lucile Packard Foundation, Thorrold and colleagues plan to use harmless chemical tags to track the dispersal of the larvae of coral reef fishes in the western Pacific Ocean. The Packard Foundation's Conservation and Science Program has granted Thorrold and colleagues more than $480,000 for three years to study the population dynamics of grouper and snapper in the waters around the Great Barrier Reef and Papua New Guinea.

Through a new technique known as TRAnsgenerational Isotope Labeling (TRAIL), the researchers will introduce an artificial tag-a stable isotope of barium-into the tissues of mature female fish just before spawning. That chemical tag is then passed to the female's offspring and becomes a chemical signature within the ear bones (otoliths) of the next generation of fish. Researchers can then track the dispersal of the tagged larvae across reefs and large stretches of open ocean.

This chemical tagging approach has been successfully tested in limited studies with clownfish and butterflyfish. Now, Thorrold and colleagues want to attempt one of the first large-scale, empirical tests of the effectiveness of marine protected areas. The scientists will attempt to assess how far and how effectively the larvae spawned within protected areas are contributing to populations outside of their human-described borders.

Most management and conservation strategies assume that fish populations may be connected across broad areas, and that protecting them in one location will allow for sustainable fisheries outside of the reserve boundaries. But such theories are mostly untested and do not necessarily account for how long and how far larvae may or may not drift in the open ocean.

The new research program will be led by Thorrold, an associate scientist in the WHOI Department of Biology. Co-investigators include Glenn Almany, Geoffrey Jones, and Garry Russ of the ARC Centre of Excellence for Coral Reef Studies and James Cook University (Australia), and Rick Hamilton of The Nature Conservancy.

The David and Lucile Packard Foundation was created in 1964 by David Packard, cofounder of the Hewlett-Packard Company, and Lucile Salter Packard. The Foundation's Conservation and Science Program seeks to protect and restore our oceans, coasts, and atmosphere, and to enable the creative pursuit of scientific research.

The Woods Hole Oceanographic Institution is a private, independent organization in Falmouth, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the oceans and their interaction with the Earth as a whole, and to communicate a basic understanding of the ocean's role in the changing global environment.

More about Marine biology

In nations such as Japan, Norway, and Iceland, whales are increasingly regarded as a pests competing with rapidly dwindling fisheries. The change in perception could have important implications for how whales are protected and their populations managed, according to a recent research article.

Despite the international moratorium on whaling agreed to by most governments in 1986, a handful of nations with a long history of whaling continue to hunt the marine mammals for research projects-and meat
"To nations with whalers, or to those currently reviving whaling, whales are no longer natural resources to be managed sustainably, but are competitors for fisheries," said the author of the article, conservation biologist Peter Corkeron of the Norwegian Institute of Marine Research in Tromsoe.

Culls in Sight?

The governments of Japan and Norway now claim that species such as the minke whale (Balaenoptera acutorostrata) have rebounded to such numbers that they are a factor behind plummeting populations of fish hunted for human consumption the world over. The WWF last month said the global cod catch had dropped by 70 percent in the last 30 years and that cod could disappear completely within another 15 years if the trend continues.

"The logical extension of this idea is that whales should not be allowed to recover to environmental carrying capacity, but rather are in need of culling in the name of ecosystem management," Corkeron said.

He points to the example of how seal populations are managed in some North Atlantic nations as one possible scenario for the future control of whales-Canada allowed the culling of 350,000 seals earlier this year in a move it claimed was necessary to protect commercial fish stocks.

"As our impact on the oceans grows and fish disappear, our perception of how to share the reduced wealth of the oceans with whales is changing," Corkeron wrote in his in his article, which was published in the June edition of the science journal Conservation Biology. The article also called for debate in the scientific community on how whales are used as conservation icons and whether whale watching has a negative effect on the animals and the environment.

On May 18 of this year, Norway's parliament passed a resolution calling for a threefold increase in the hunting quota for minke whales, to preserve cod and other prey for fishers. A Norwegian Ministry of Fisheries report claimed that 5.5 million tons of fish are eaten by marine mammals in Norwegian waters, compared with just 2.74 million tons taken by Norwegian fisheries in 2002. "This indicates the competition between humans and marine mammals, which must be given considerable weight in managing these species," the report said.

Similarly, in February, Japan's delegation to a United Nation's fisheries meeting in Rome claimed that Japan's scientific whaling program in the North Pacific has revealed that whales are a significant competitor for fish stocks.

A Japanese Fisheries Agency spokesperson said that whales eat at least ten target species hunted by people, including Japanese anchovy and Pacific saury. Other figures suggested that whales and dolphins worldwide consume 300 to 500 million tons of marine food annually-three to six times the amount fished for total human consumption.

A spokesperson for the International Fund for Animal Welfare (IFAW), based in Yarmouth Port, Massachusetts, said the tactic employed by Japan and Norway is a ploy to get around the international moratorium on whaling.

Winners and Losers
It is true that some whale populations-such as humpbacks in the Southern Hemisphere, fin whales in the Northern Hemisphere, and minke whales in the North Atlantic and North Pacific-seem to be recovering since the implementation of a moratorium on wide-scale commercial whaling, Corkeron said.

But there are still question marks over the future of populations of other species, including blue whales and bowhead whales, both hunted to the verge of extinction.

"The bottom line is that we are exploiting the oceans' resources more and more," Corkeron told National Geographic News. "It's almost a no-brainer that eventually someone will point the finger at other species that are using the same resources."

Regarding whales as pests, rather than natural resources, could have important implications for how people view species such as minke whales, Corkeron said. People tend to want to eradicate pests, he said.

"The issue of culling whales has been important for several years … [and] is about misrepresenting the scientific evidence to create a deceptively plausible reason for killing more whales," commented David Lavigne, a biologist with IFAW. "While some whale populations have shown signs of recovery, others have not."

There is no hard evidence to confirm that whales are conflicting with fishers, Lavigne said. "In virtually all cases, scientists cannot predict with certainty the effects of reducing marine mammal populations on the abundance of fish stocks."

Culling whales could even be detrimental to fishing interests, he said. For example, if whales consume predators of important commercially fished species, then culling could just as plausibly deplete fish stocks.

Human Overexploitation

Problems fisheries are facing are generally not due to whale populations having recovered to historic levels, said Ken Balcomb, whale biologist at the Center for Whale Research in Friday Harbor, Washington. "Rather, the bar has been lowered by human overexploitation of some fisheries to the point that there is some whale competition for the resources," he said.

"A properly managed fishery should allow for a healthy stock of natural predators and should follow their example of not taking 95 percent of the standing stocks of prey, as many fisheries have done."

Besides, added Balcomb, most whales that have been commercially hunted eat species low in the food chain (such as herring or krill), the consumption of which should not be a significant burden to human fisheries.

"The issue of whales versus fish is fast becoming the central issue in the whaling debate," commented Phillip Clapham, marine biologist at the Northeast Fisheries Science Center in Woods Hole, Massachusetts, and member of the Scientific Committee of the International Whaling Commission.

However, the argument for culling whales ignores the fact that human fisheries, not whales, are responsible for the dreadful state of many fish stocks, Clapham said, "Japan being one of the major guilty parties.

"The idea that whales are out there, eating our fish, … is an absurd oversimplification of marine ecological relationships. Even if we did cull lots of whales, it's unlikely that this would result in more fish for human fisheries, since other fish, not whales, are the major predators of fish

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