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Identification of Juvenile Fall versus Spring Chinook Salmon Migrating through the Lower Snake River Based on Body Morphology
Author(s) -
Tiffan Kenneth F.,
Rondorf Dennis W.,
Garland Rodney D.,
Verhey Peter A.
Publication year - 2000
Publication title -
transactions of the american fisheries society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 86
eISSN - 1548-8659
pISSN - 0002-8487
DOI - 10.1577/1548-8659(2000)129<1389:iojfvs>2.0.co;2
Subject(s) - chinook wind , oncorhynchus , fishery , spring (device) , juvenile , biology , ecology , fish <actinopterygii> , mechanical engineering , engineering
We tested the use of body morphology to distinguish among subyearling fall‐run, subyearling spring‐run, and yearling spring‐run smolts of chinook salmon Oncorhynchus tshawytscha at two lower Snake River dams during the summer emigration. Based on principal‐components analysis, subyearling fall‐run chinook salmon had smaller heads and eyes, deeper bodies, and shorter caudal peduncles than yearling spring‐run chinook salmon. Subyearling spring‐run chinook salmon had characteristics of both subyearling fall‐run and yearling spring‐run chinook salmon. Subyearling fall‐run and yearling spring‐run chinook salmon were classified with more than 80% accuracy by means of discriminant analysis. Classification accuracy for subyearling spring‐run chinook salmon was only 26%. We conclude that body morphology can be used to accurately identify the age of chinook salmon smolts but not the run. Therefore, genetic analyses are the only means of reliably determining the run composition of summer migrants in the lower Snake River.