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Northern shrimp like it cold

Northern shrimp (panaslus borealis) on ocean bottom.

Northern shrimp the small, sweet ones that you're likely to see in salad use temperature as a cue for egg-laying and may therefore be seriously vulnerable to climate change, scientists say in a new study.

These findings help show how important it is that scientists and the people who manage shrimp and other fisheries learn more about the different ways that sea life can be affected by climate change. With this knowledge, they may be able to make decisions that help protect our oceans.

Northern shrimp, called Pandalus borealis, make up about 70 percent of the 500,000 tons of cold-water shrimp that is harvested each year. These shrimp are generally considered a more sustainable alternative to other types of shrimp that are farmed or trawled in warmer waters.

Eggs on abdomen of female northern shrimp.

In a new study, Peter Koeller of the Bedford Institute of Oceanography in Nova Scotia and his colleagues compared the timing of the shrimp egg laying and hatching, and compared that to the timing of the local spring algae bloom, which is a source of food for the shrimp larvae.

They report that the shrimp's reproductive cycles are finely tuned to the timing of the bloom.

But, the algae themselves don't trigger the egg-laying, like you might expect. Instead, the female shrimp use the local ocean bottom-water temperatures as the signal that tells them to lay their eggs.

Over the long-term, this strategy works because the ocean temperature and bloom timing are generally well-matched. But, in the short term, there can be variations from year to year in the temperature or bloom timing. These variations could become more frequent as global climate change progresses, which may throw off the shrimps' system for reproducing when the most food is available.


This research appears in the 8 May 2009 issue of the journal Science.