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David A. Beauchamp

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Stomach contents were collected and analysed from 22 bull trout Salvelinus confluentus at the edge of the Chilko Lake and Chilko River in British Columbia, Canada, during spring outmigration of sockeye salmon Oncorhynchus nerka smolts. Twenty of the 22 (>90%) stomachs contained prey items, virtually all identifiable prey items were outmigrant O. nerka smolts and stomach contents represented a large portion (0·0–12·6%) of estimated S. confluentus mass. The results demonstrate nearly exclusive and intense feeding by S. confluentus on outmigrant smolts, and support recent telemetry observations of high disappearance rates of O. nerka smolts leaving large natural lake systems prior to entering high-order unregulated...
Categories: Publication; Types: Citation; Tags: Journal of Fish Biology
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Understanding the limits of consumption is important for determining trophic influences on ecosystems and predator adaptations to inconsistent prey availability. Fishes have been observed to consume beyond what is sustainable (i.e. digested on a daily basis), but this phenomenon of hyperphagia (or binge-feeding) is largely overlooked. We expect hyperphagia to be a short-term (1-day) event that is facilitated by gut volume providing capacity to store consumed food during periods of high prey availability to be later digested.We define how temperature, body size and food availability influence the degree of binge-feeding by comparing field observations with laboratory experiments of bull trout (Salvelinus confluentus),...
Categories: Publication; Types: Citation; Tags: Journal of Animal Ecology
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We examined the effect of early marine entry timing and body size on the marine (smolt-to-adult) survival of Puget Sound Chinook salmon (Oncorhynchus tshawytscha). We used data from coded wire tag release groups of hatchery Chinook salmon to test whether hatchery release date, release size, and size in offshore waters in July and September influenced marine survival. Marine survival was most strongly related to the average body size in July, with larger sizes associated with higher survivals. This relationship was consistent over multiple years (1997–2002), suggesting that mortality after July is strongly size-dependent. Release size and date only slightly improved this relationship, whereas size in September showed...
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Copper contamination in surface waters is common in watersheds with mining activities or agricultural, industrial, commercial, and residential human land uses. This widespread pollutant is neurotoxic to the chemosensory systems of fish and other aquatic species. Among Pacific salmonids (), copper-induced olfactory impairment has previously been shown to disrupt behaviors reliant on a functioning sense of smell. For juvenile coho salmon (O. kisutch), this includes predator avoidance behaviors triggered by a chemical alarm cue (conspecific skin extract). However, the survival consequences of this sublethal neurobehavioral toxicity have not been explored. In the present study juvenile coho were exposed to low levels...
Categories: Publication; Types: Citation; Tags: Ecological Applications
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