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Occurrence, size, and tag retention of sneaker male hatchery rainbow trout

North American Journal of Aquaculture

By:
and
DOI: 10.1577/A03-023.1

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Abstract

One alternative reproductive tactic involving early-maturing, cryptic males is referred to as "sneaking." Although sneakers tend to be easily detectable upon close inspection, little is known about the proportion of a fish population consisting of sneakers. We examined 15,400 age-1 rainbow trout Oncorhynchus mykiss in a hatchery. Total length (mm), wet weight (g), and sex (sneaker male or unknown) were recorded for each fish. We also individually tagged each sneaker male with soft visual implant alphanumeric (VIalpha) tags that were sequentially numbered and held the fish for 25 d before inspection. Sneakers constituted 2.8% of the hatchery rainbow trout population and were smaller in total length and weight than typical rainbow trout of the same age. Retention of the VIalpha tags in sneakers was 58.9%, significantly lower than has been reported under similar circumstances. We found that sneaker males may contribute substantially to hatchery populations. Reduced tag retention in sneakers may bias studies evaluating the effect of hatchery fish on wild populations. We believe that hatchery-produced sneaker males have the potential to contribute importantly to the genetic composition of wild populations.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Occurrence, size, and tag retention of sneaker male hatchery rainbow trout
Series title:
North American Journal of Aquaculture
DOI:
10.1577/A03-023.1
Volume
66
Issue:
3
Year Published:
2004
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
North American Journal of Aquaculture
First page:
234
Last page:
236