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Spatial and trophic overlap of marked and unmarked Columbia River Basin spring Chinook salmon during early marine residence with implications for competition between hatchery and naturally produced fish

ScholarsArchive at Oregon State University

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Title Spatial and trophic overlap of marked and unmarked Columbia River Basin spring Chinook salmon during early marine residence with implications for competition between hatchery and naturally produced fish
Names Daly, Elizabeth A. (creator)
Brodeur, Richard D. (creator)
Fisher, Joseph P. (creator)
Weitkamp, Laurie A. (creator)
Teel, David J. (creator)
Beckman, Brian R. (creator)
Date Issued 2011-06-04 (iso8601)
Note To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work.
This is the publisher’s final pdf. The published article is copyrighted by Springer and can be found at: http://www.springer.com/?SGWID=0-102-0-0-0.
Abstract Ecological interactions between natural and
hatchery juvenile salmon during their early marine
residence, a time of high mortality, have received little
attention. These interactions may negatively influence
survival and hamper the ability of natural populations to
recover. We examined the spatial distributions and size
differences of both marked (hatchery) and unmarked (a
high proportion of which are natural) juvenile Chinook
salmon in the coastal waters of Oregon andWashington
from May to June 1999–2009. We also explored
potential trophic interactions and growth differences
between unmarked and marked salmon. Overlap in
spatial distribution between these groups was high,
although catches of unmarked fish were low compared
to those of marked hatchery salmon. Peak catches of
hatchery fish occurred in May, while a prolonged
migration of small unmarked salmon entered our study
area toward the end of June. Hatchery salmon were
consistently longer than unmarked Chinook salmon
especially by June, but unmarked salmon had significantly
greater body condition (based on length-weight
residuals) for over half of the May sampling efforts.
Both unmarked and marked fish ate similar types and
amounts of prey for small (station) and large (month,
year) scale comparisons, and feeding intensity and
growth were not significantly different between the
two groups. There were synchronous interannual
fluctuations in catch, length, body condition, feeding
intensity, and growth between unmarked and hatchery
fish, suggesting that both groups were responding
similarly to ocean conditions.
Genre Article
Topic Columbia River Basin
Identifier Daly, E. A., Brodeur, R. D., Fisher, J. P., Weitkamp, L. A., Teel, D. J., & Beckman, B. R. (2012). Spatial and trophic overlap of marked and unmarked columbia river basin spring chinook salmon during early marine residence with implications for competition between hatchery and naturally produced fish. Environmental Biology of Fishes, 94(1), 117-134. doi: 10.1007/s10641-011-9857-4

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