Abstract
We examined how climatic regime shifts may have affected predation rates on juvenile Pacific salmonids (Oncorhynchus spp.) by northern squawfish (Ptychocheilus oregonensis, also called northern pikeminnow), smallmouth bass (Micropterus dolomieu), and walleye (Stizostedion vitreum) in the Columbia River. During 19331996, oceanic, coastal, and freshwater indices of climate were highly correlated, and an index for the Columbia River Basin suggested that climate shifts may have occurred about 1946, 1958, 1969, and 1977. Summer water temperature varied as much as 2°C between climate periods. We used a bioenergetics model for northern squawfish, the most important piscivore, to predict that predation on salmonids would have been 2631% higher during two periods with relatively warm springsummer water temperatures (19331946, 19781996) than during an extremely cold period (19471958). Predicted predation rates of northern squawfish were 6896% higher in the warmest year compared with the coldest year. Predation rates of smallmouth bass and walleye on juvenile salmonids varied among climate periods similar to rates predicted for northern squawfish. Climatic effects need to be understood in both freshwater and nearshore marine habitats, since growth rates of salmon populations are especially sensitive to mortality during early life stages.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
More From: Canadian Journal of Fisheries and Aquatic Sciences
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.