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Over-winter lipid depletion and mortality of age-0 rainbow trout (Oncorhynchus mykiss)

journal contribution
posted on 2004-08-01, 00:00 authored by Peter BiroPeter Biro, A Morton, J Post, E Parkinson
In this study we identify the size-dependent risk of winter starvation mortality as a strong selective pressure on age-0 rainbow trout (Oncorhynchus mykiss) that could promote the risk-taking behaviour and allocation of energy to lipids previously observed in young trout cohorts. Age-0 trout subjected to simulated winter starvation conditions gradually depleted lipid reserves to a critical minimum lipid content below which death occurred. Small fish with lower lipid content exhausted lipid reserves earlier, and experienced high mortality rates sooner, than larger fish with greater lipid content. Consequently, winter starvation endurance was dependent upon size-dependent lipid reserves and winter duration. To validate the laboratory findings in the field, we stocked several size classes of hatchery-raised trout with known lipid content at the start of winter into two experimental lakes, and estimated survival and lipid depletion at winter's end. Larger age-0 trout had greater initial lipid reserves than smaller trout. Individuals depleted most of their lipid reserves over the winter, and experienced mortality that ranged from just under 60% for the largest individuals to just over 90% of the smallest individuals. Many survivors had lipid contents near, but none were below, the minimum lipid content determined in the laboratory.

History

Journal

Canadian journal of fisheries and aquatic sciences

Volume

61

Issue

8

Pagination

1513 - 1519

Publisher

N R C Research Press

Location

Ottawa, Ont.

ISSN

0706-652X

eISSN

1205-7533

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

2004, NRC Canada