Skip to Main Content
Instream cover and shade mediate avian predation on trout in semi-natural streamsAuthor(s): Brooke E. Penaluna; Jason B. Dunham; David L. G. Noakes
Source: Ecology of Freshwater Fish
Publication Series: Scientific Journal (JRNL)
Station: Pacific Northwest Research Station
Download Publication (2.0 MB)
DescriptionPiscivory by birds can be significant, particularly on fish in small streams and during seasonal low flow when available cover from predators can be limited. Yet, how varying amounts of cover may change the extent of predation mortality from avian predators on fish is not clear. We evaluated size-selective survival of coastal cutthroat trout (Oncorhynchus clarkii clarkii) in replicated semi-natural stream sections. These sections provided high (0.01 m2 of cover per m2 of stream) or low (0.002 m2 of cover per m2 of stream) levels of instream cover available to trout and were closed to emigration. Each fish was individually tagged, allowing us to track retention of individuals during the course of the 36-day experiment, which we attributed to survival from predators, because fish had no other way to leave the streams. Although other avian predators may have been active in our system and not detected, the only predator observed was the belted kingfisher Megaceryle alcyon, which is known to prey heavily on fish. In both treatments, trout >20.4 cm were not preyed upon indicating an increased ability to prey upon on smaller individuals. Increased availability of cover improved survival of trout by 12% in high relative to low cover stream sections. Trout also survived better in stream sections with greater shade, a factor we could not control in our system. Collectively, these findings indicate that instream cover and shade from avian predators can play an important role in driving survival of fish in small streams or during periods of low flow.
- Visit PNW's Publication Request Page to request a hard copy of this publication.
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
CitationPenaluna, Brooke E.; Dunham, Jason B.; Noakes, David L. G. 2015. Instream cover and shade mediate avian predation on trout in semi-natural streams. Ecology of Freshwater Fish, Vol. 25(3): 7 pages.: 405-411.
KeywordsTrout survival, refuge, piscivory, body size, low flow, experiment
- Instream cover and shade mediate avian predation on trout in semi-natural streams
- Quantifying fish responses to forestry—lessons from the trask watershed study
- Nowhere to hide: The importance of instream cover for stream‐living Coastal Cutthroat Trout during seasonal low flow
XML: View XML