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27 November 2013 12:59 pm ,
Vol. 342 ,
The new head of the National Center for Science Education promises to "fight the good fight" against attacks on...
Analyses of the H7N9 strains isolated from four new cases show that the virus is evolving rapidly, heightening anxiety...
In 2009, Jack Szostak shared a Nobel Prize for his part in discovering the role of telomeres, the end bits of...
Science has exposed a thriving academic black market in China involving shady agencies, corrupt scientists, and...
Paper-selling agencies flourish in the aura of reputable businesses. For some scientists, it may be difficult to tell...
Featuring the first lunar rover in 40 years, Chang'e-3 is seen as an important milestone on China's quest to send a...
Data collected by satellites and floating probes have chronicled a 2-decade rise in the temperature and thickness of a...
Cholesterol, the artery-clogging molecule that contributes to cardiovascular disease, has another nasty trick up its...
- 27 November 2013 12:59 pm , Vol. 342 , #6162
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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.