Climate regimes and water temperature changes in the Columbia River: bioenergetic implications for predators of juvenile salmon

Authors: Petersen J.H.; Kitchell J.F.

Source: Canadian Journal of Fisheries and Aquatic Sciences, Volume 58, Number 9, September 2001 , pp. 1831-1841(11)

Publisher: NRC Research Press

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 1933–1996, 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 26–31% higher during two periods with relatively warm spring–summer water temperatures (1933–1946, 1978–1996) than during an extremely cold period (1947–1958). Predicted predation rates of northern squawfish were 68–96% 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.

Nous avons examiné comment les changements de régime climatique peuvent avoir affecté les taux de prédation des jeunes saumons du Pacifique (Oncorhynchus spp.) par la Sauvagesse du Nord (Ptychocheilus oregonensis, aussi appelé le Méné-brocheton du Nord), l'Achigan à petite bouche (Micropterus dolomieu) et le Doré jaune (Stizostedion vitreum) dans le Columbia. De 1933 à 1996, les indices climatiques de l'océan, de la côte et des eaux douces montrent une forte corrélation et un indice calculé pour le bassin versant du Columbia laisse croire à l'existence de changements climatiques vers 1946, 1958, 1969 et 1977. Les températures estivales de l'eau ont subi des variations pouvant atteindre 2°C d'une période climatique à une autre. Un modèle bioénergétique a permis de prédire que, chez la Sauvagesse du Nord, le piscivore le plus important, la prédation des salmonidés aurait été de 26–31% plus élevée durant les deux périodes où les températures de printemps et d'été ont été relativement plus chaudes (1933–1946, 1978–1996) que pendant une période très froide (1947–1958). Les taux prédits de prédation sont de 68–96% plus élevés l'année la plus chaude que l'année la plus froide. La prédation exercée par les Achigans à petite bouche et les Dorés jaunes sur les salmonidés a varié d'une période à l'autre selon les taux prédits chez la Sauvagesse du Nord. Il est donc essentiel de comprendre les effets des changements climatiques, tant dans les eaux douces que dans les habitats marins côtiers, puisque les taux de croissance des populations de saumons sont particulièrement sensibles à la mortalité durant les premiers stades de vie.[Traduit par la Rédaction]

Language: English

Document Type: Research article

Publication date: 2001-09-01

• Published continuously since 1901 (under various titles), this monthly journal is the primary publishing vehicle for the multidisciplinary field of aquatic sciences. It publishes perspectives (syntheses, critiques, and re-evaluations), discussions (comments and replies), articles, and rapid communications, relating to current research on cells, organisms, populations, ecosystems, or processes that affect aquatic systems. The journal seeks to amplify, modify, question, or redirect accumulated knowledge in the field of fisheries and aquatic science. Occasional supplements are dedicated to single topics or to proceedings of international symposia.
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