In a paper published in the open access journal PLoS Biology, researchers used new tagging and tracking technologies to show the surprising result that the survival of juvenile salmon in two major west coast rivers was similar, despite the presence of an extensive network of dams in one river system.
Researchers have used tags to follow larger ocean dwellers such as sharks, sturgeon, tuna and sea turtles, and to follow migrations of mature salmon along marine coasts. Now for the first time they have tagged and directly tracked small juvenile Pacific salmon, from their release in freshwater far upriver to distant ocean destinations, a major step towards understanding the full life experience and decline of this species.
The authors stress that dams are not good for salmon. What is unclear is whether the Fraser River has a problem that cuts salmon survival to that of a heavily dammed river, or whether factors other than dams play a larger, unsuspected role in salmon survival.
Says lead author David Welch: Wherever future research leads on those questions, the electronic and acoustic technology has demonstrated itself as a useful tool for obtaining unique scientific data of importance in a number of public policy arenas.
In 2006, the researchers implanted the new tags in roughly 1,000 juvenile steelhead (www.eol.org/taxa/17050441) and Chinook salmon (www.eol.org/taxa/17154704) roughly the same length and half the weight of a hot dog, 14-17 centimeters long, 20-30 grams weight for a study in the Columbia and Fraser Rivers, and followed their journeys. The 1,000 tagged juvenile salmon were followed via an extensive network of detectors in the Columbia and Fraser Rivers and along the Pacific continental shelf.
The underwater array of detectors in the rivers and ocean capture signals when a tagged fish passes by, akin to an electronic toll boo
|Contact: Sally Hubbard|
Public Library of Science