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Length and Condition of Wild Chinook Salmon Smolts Influence Age at Maturity
Author(s) -
Tattam Ian A.,
Ruzycki James R.,
McCormick Josh L.,
Carmichael Richard W.
Publication year - 2015
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 - 10.1080/00028487.2015.1082503
Subject(s) - oncorhynchus , sexual maturity , biology , chinook wind , smoltification , fish measurement , tributary , fishery , population , abiotic component , maturity (psychological) , salmonidae , ecology , demography , geography , fish <actinopterygii> , salmo , cartography , sociology , psychology , developmental psychology
Anadromous Chinook Salmon Oncorhynchus tshawytscha commonly mature at 3–5 years of age. Age at maturity is an important measure of population diversity, and has ecological importance. In the John Day River, a northeast Oregon tributary of the Columbia River, we tagged 24,240 wild Chinook Salmon smolts from 10 successive cohorts with passive integrated transponder tags and subsequently monitored their age at maturation. We used multinomial logistic regression and multimodel selection to assess the influence of biotic and abiotic factors on age at maturity. Smolt fork length, condition factor, and day of tagging all had significant associations with age at maturity. Conversely, we found no significant association between ocean conditions and age at maturity. The probability of age‐3 maturation increased concomitant with increased smolt length. In contrast, the probability of maturation at age‐5 was inversely related to smolt condition factor. Day of tagging had a significant effect, indicating that smolts tagged later in the spring had a higher probability of maturing at age 4 than age 3. Our data indicate that mean smolt size was greater when smolt abundance was lower, and larger smolts were ultimately associated with a younger age at maturity. For John Day Chinook Salmon, spawner escapements approaching or exceeding the stock–recruit replacement level appear to favor production of older Chinook Salmon.