The Heat Is Online

North Atlantic Shrimp Decline Could Imperil Food Chain

Shrimp Said At Risk From North Atlantic Warming


Reuters News Service, May 8, 2009


OSLO - A $500 million North Atlantic shrimp fishery may be vulnerable to climate change that could disrupt the crustaceans' life cycle and mislead them into hatching when food is scarce, scientists said.


Any damage to stocks of the northern shrimp -- a small, sweet-tasting variety popular in salads -- could have knock-on effects in the ocean food chain ranging from algae to cod, according to a Canadian-led team of experts.


"The shrimp is the marine equivalent of the canary in the mine shaft. It's an indicator of climate change," Peter Koeller, the lead author of the study at the Bedford Institute of Oceanography in Canada, told Reuters.


Writing in Friday's edition of the journal Science, the scientists said that the shrimp timed mating so that their eggs hatch when algae that shrimp larvae feed on are most abundant.


"They have evolved to mate the previous year at just the right time to take advantage of spring blooms," said Koeller. Eggs carried by the females take between 6 and 10 months to incubate over the winter.


"But climate change could decouple the match" between seabed temperatures and food, he said of findings with colleagues in the United States, Britain, Denmark, Iceland and Norway.


The scientists found that the crustaceans, which live from the Gulf of Maine to Arctic waters north of Norway, time their mating according to water temperatures on the seabed where the adults live. Warmer waters could disrupt that timing.


Previously, one theory had been that the larvae hatched in direct response to a chemical trigger from the blooms, for instance cued by dead algae drifting down from the surface.


The shrimp make up about 70 percent of the 500,000 tons of cold-water shrimp harvested annually from the world's oceans. Koeller said the fishery was worth about $500 million.


Koeller said shrimp were an important link in the food chain -- they feed on algae and are in turn eaten by fish. Overfishing of cod has helped a sharp rise in shrimp populations.


The U.N. Climate Panel says that a build-up of greenhouse gases in the atmosphere, caused mainly by mankind's use of fossil fuels, could push up world temperatures and cause more heatwaves, more powerful storms and rising ocean levels.


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