Monday 6 August 2012

Bears, Scavengers Count On All-You-Can-Eat Salmon Buffet Lasting for Months

ScienceDaily (Aug. 3, 2012) — Salmon conservation shouldn't narrowly focus on managing flows in streams and rivers or on preserving only places that currently have strong salmon runs. Instead, watersheds need a good mix of steep, cold-running streams and slower, meandering streams of warmer water to keep options open for salmon adapted to reproduce better in one setting than the other, new research shows.

Preserving that sort of varied landscape serves not just salmon, it provides an all-summer buffet that brown bears, gulls and other animals need to sustain themselves the rest of the year.

"In any one stream, salmon might spawn for two to four weeks," said Peter Lisi, a University of Washington doctoral student in aquatic and fishery sciences, who studies the Wood River watershed in southwest Alaska.

"Animals like coastal brown bears and Glaucus-winged gulls gorge themselves at one stream for a few weeks and then just move to another stream that might have water temperatures a few degrees warmer and therefore support salmon populations that spawn at a later time," he said. "It's easy for animals to move when such streams are as little as a mile or two apart."

A whole network of streams, some colder and some warmer, provides what Lisi and Daniel Schindler, UW professor of aquatic and fishery sciences, call "hydrological diversity." Such diversity more than triples the time predators have access to salmon in a summer, from just a few weeks to more than three months in the watershed studied.

Continued:
http://www.sciencedaily.com/releases/2012/08/120803094427.htm

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