Floodplain rearing of juvenile chinook salmon: evidence of enhanced growth and survival

In this study, we provide evidence that the Yolo Bypass, the primary floodplain of the lower Sacramento River (California, U.S.A.), provides better rearing and migration habitat for juvenile chinook salmon (Oncorhynchus tshawytscha) than adjacent river channels. During 1998 and 1999, salmon increase...

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Bibliographic Details
Published in:Canadian journal of fisheries and aquatic sciences 2001-02, Vol.58 (2), p.325-333
Main Authors: Sommer, T R, Nobriga, M L, Harrell, W C, Batham, W, Kimmerer, W J
Format: Article
Language:English
Subjects:
Agnatha. Pisces
Animal and plant ecology
Animal behavior
Animal, plant and microbial ecology
Animals
Autoecology
Biological and medical sciences
Fish
Fisheries management
Floodplains
Freshwater
Fundamental and applied biological sciences. Psychology
Growth rate
Habitats
Oncorhynchus tshawytscha
Rivers
Salmon
USA, California
Vertebrata
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Summary:In this study, we provide evidence that the Yolo Bypass, the primary floodplain of the lower Sacramento River (California, U.S.A.), provides better rearing and migration habitat for juvenile chinook salmon (Oncorhynchus tshawytscha) than adjacent river channels. During 1998 and 1999, salmon increased in size substantially faster in the seasonally inundated agricultural floodplain than in the river, suggesting better growth rates. Similarly, coded-wire-tagged juveniles released in the floodplain were significantly larger at recapture and had higher apparent growth rates than those concurrently released in the river. Improved growth rates in the floodplain were in part a result of significantly higher prey consumption, reflecting greater availability of drift invertebrates. Bioenergetic modeling suggested that feeding success was greater in the floodplain than in the river, despite increased metabolic costs of rearing in the significantly warmer floodplain. Survival indices for coded-wire-tagged groups were somewhat higher for those released in the floodplain than for those released in the river, but the differences were not statistically significant. Growth, survival, feeding success, and prey availability were higher in 1998 than in 1999, a year in which flow was more moderate, indicating that hydrology affects the quality of floodplain rearing habitat. These findings support the predictions of the flood pulse concept and provide new insight into the importance of the floodplain for salmon.
ISSN:0706-652X
1205-7533
DOI:10.1139/f00-245