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5 December 2013 11:26 am ,
Vol. 342 ,
An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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Salmon Run Hot and Cold
30 October 2000 7:00 pm
Pacific salmon populations have plummeted recently, due to overfishing, dams, and disease. Now it turns out that a more natural force can also drive salmon numbers: climate. Using a new technique, paleoceanographers have traced the ups and downs of salmon populations in Alaskan lakes for hundreds of years.
Near Kodiak Island and Bristol Bay on Alaska's southern coast, among other sites along the Pacific Coast, sockeye salmon hatch and spend their youth in lakes. Then, after 1 to 3 years, they migrate to the Pacific. The sockeyes feast on plankton, squid, and small fish, eventually doubling their initial body weight. At the ripe old age of 5 or 6, the salmon return home, spawn, and die.
The sockeyes' seafood diet makes them easy to track, according to paleoceanographer Bruce Finney of the University of Alaska, Fairbanks, and colleagues. As they eat, the fish take on a high ratio of a nitrogen isotope called nitrogen-15. Later, when the salmon die in their freshwater homes, the isotope is consumed by microorganisms and eventually settles to the bottom of the lake. Finney's team took core samples from several Alaskan salmon nursery lakes and measured levels of nitrogen-15 going back 3 centuries. They correlated the isotope levels with tree-ring climate data and found that warm waters were associated with thriving salmon populations, they report in the 27 October issue of Science.
"This paper is terribly important, because it's the first solid proof that salmon abundance fluctuates naturally," says ecologist Richard Beamish of Canada's Department of Fisheries and Oceans. Although many researchers have assumed that climate variability affects Pacific salmon, precise data have been scarce. Now, Beamish says, fisheries managers might take climate into account when they set harvest limits or evaluate population swings.