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Estuarine environments as rearing habitats for juvenile Coho Salmon in contrasting south-central Alaska watersheds

Transactions of the American Fisheries Society

By:
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DOI: 10.1080/00028487.2013.815660

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Abstract

For Pacific salmon, estuaries are typically considered transitional staging areas between freshwater and marine environments, but their potential as rearing habitat has only recently been recognized. The objectives of this study were two-fold: (1) to determine if Coho Salmon Oncorhynchus kisutch were rearing in estuarine habitats, and (2) to characterize and compare the body length, age, condition, and duration and timing of estuarine occupancy of juvenile Coho Salmon between the two contrasting estuaries. We examined use of estuary habitats with analysis of microchemistry and microstructure of sagittal otoliths in two watersheds of south-central Alaska. Juvenile Coho Salmon were classified as estuary residents or nonresidents (recent estuary immigrants) based on otolith Sr : Ca ratios and counts of daily growth increments on otoliths. The estuaries differed in water source (glacial versus snowmelt hydrographs) and in relative estuarine and watershed area. Juvenile Coho Salmon with evidence of estuary rearing were greater in body length and condition than individuals lacking evidence of estuarine rearing. Coho Salmon captured in the glacial estuary had greater variability in body length and condition, and younger age-classes predominated the catch compared with the nearby snowmelt-fed, smaller estuary. Estuary-rearing fish in the glacial estuary arrived later and remained longer (39 versus 24 d of summer growth) during the summer than did fish using the snowmelt estuary. Finally, we observed definitive patterns of overwintering in estuarine and near shore environments in both estuaries. Evidence of estuary rearing and overwintering with differences in fish traits among contrasting estuary types refute the notion that estuaries function as only staging or transitional habitats in the early life history of Coho Salmon.

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Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Estuarine environments as rearing habitats for juvenile Coho Salmon in contrasting south-central Alaska watersheds
Series title:
Transactions of the American Fisheries Society
DOI:
10.1080/00028487.2013.815660
Volume
142
Issue:
6
Year Published:
2013
Language:
English
Publisher:
Taylor & Francis Online
Contributing office(s):
Alaska Science Center
Description:
16 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Transactions of the American Fisheries Society
First page:
1481
Last page:
1494
Country:
United States
State:
Alaska
Other Geospatial:
Kenai Peninsula