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Behavior of steelhead fry in a laboratory stream is affected by fish density but not rearing environment

North American Journal of Fisheries Management

By:
, , , and
DOI: 10.1577/M09-035.1

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Abstract

We quantified the aggression, feeding, dominance, position choice, and territory size of naturally reared steelhead Oncorhynchus mykiss fry stocked with two types of hatchery-reared fry (from conventional and enriched rearing environments) at two densities in experimental flumes to determine how rearing environment and fish density affect the behavior of steelhead fry. We found that fry density had a significant effect on most response variables but that rearing treatment did not. The rates of threats and attacks were positively correlated with fry density, but the overall feeding rate was negatively correlated. Naturally reared fry were dominant more often at low densities, and hatchery-reared fry were dominant more often at high densities. There were no significant effects of hatchery rearing treatment on aggression, feeding, dominance, or territory size. The only significant effect of rearing treatment was on the position of naturally reared fry, which occupied more upstream positions when stocked with conventional than with enriched hatchery-reared fry. Overall, rearing environment had relatively little influence on the behavior of steelhead fry. Our results indicate that stocking hatchery-reared steelhead fry at low densities may have effects on similar-size wild fish comparable to an equivalent increase in the density of wild fish. We suggest that releasing hatchery-reared steelhead fry as a supplementation strategy may have few direct negative ecological effects on wild fry.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Behavior of steelhead fry in a laboratory stream is affected by fish density but not rearing environment
Series title:
North American Journal of Fisheries Management
DOI:
10.1577/M09-035.1
Volume
29
Issue:
6
Year Published:
2009
Language:
English
Publisher:
Taylor & Francis
Publisher location:
London, UK
Contributing office(s):
Great Lakes Science Center
Description:
13 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
North American Journal of Fisheries Management
First page:
1806
Last page:
1818
Number of Pages:
13