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Determination of Salmonid Smolt Yield with Rotary‐Screw Traps in the Situk River, Alaska, to Predict Effects of Glacial Flooding
Author(s) -
Thedinga John F.,
Murphy Michael L.,
Johnson Scott W.,
Lorenz J. Michael,
Koski K V.
Publication year - 1994
Publication title -
north american journal of fisheries management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.587
H-Index - 72
eISSN - 1548-8675
pISSN - 0275-5947
DOI - 10.1577/1548-8675(1994)014<0837:dossyw>2.3.co;2
Subject(s) - chinook wind , oncorhynchus , fishery , flooding (psychology) , flood myth , environmental science , trap (plumbing) , juvenile , hydrology (agriculture) , ecology , geography , biology , geology , fish <actinopterygii> , geotechnical engineering , environmental engineering , psychology , archaeology , psychotherapist
Hubbard Glacier is expected to dam Russell Fiord and cause glacial flooding of the lower 20 km of the Situk River near Yakutat, Alaska. To determine probable effects of the flooding on juvenile salmonids Oncorhynchus spp., two rotary‐screw traps were used to estimate smolt yield inside and outside the predicted flood zone. Traps were fished from April to mid‐August 1990: one at the predicted upstream limit of flooding and the other 3 km upstream from the river mouth. Every week, a sample of each salmonid species was tattoo‐marked and released 1 km above each trap; recaptures were used to expand catches to estimate smolt yield. Trap efficiency ranged widely among species, from 3% for steelhead O. mykiss to 24% for chinook salmon O. tshawytscha . Estimated total smolt yields were 900,000 sockeye salmon O. nerka , 213,000 coho salmon O. kisutch , 67,000 chinook salmon, and 26,000 steelhead; only sockeye salmon (34% of this species' smolts) originated in the flood zone. Estimated mortality between traps was 8% for coho salmon, 13% for chinook salmon, and 16% for sockeye salmon. Our study demonstrated that upriver and downriver rotary‐screw traps and mark‐recapture techniques can partition smolt yield, but mortality between traps and mark recognition must be considered.