7785

• UCREFRP Catalog Number: 7785
• Author: Thompson, J. M.
• Title: The Role of Size, Condition, and Lipid Content in the Overwinter Survival of Age-0 Colorado Squawfish.
• USFW Year: 1989.
• USFW - Doc Type: Colorado State University,
• Copyright Material: NO

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DISCUSSION

My laboratory results support the hypothesis that
overwinter survival of age-O Colorado squawfish is dependent
on fish size. The lipid content of hatchery-reared Colorado
squawfish increased as total length increased (Appendix E) .
For starved fish, the relation between fish length and
amount of stored energy (lipids) determined whether a fish
would survive overwinter. Fish in all size classes and
feeding regimes depleted their lipid reserves over time
(Table 6). However, only starved small and medium fish
exhausted their energy reserves and subsequently died.
Larger fish had higher initial lipid contents and,
therefore, sufficient energy reserves to survive overwinter
regardless of feeding regime.
Hoar (1983) stated that an animal must maintain a
"constant element" of fat in order to survive. Newsome and
Leduc (1975) determined that this critical level of fat
content for yellow perch was approximately 2.2% of the total
dry weight of the fish. The significantly lower lipid
content of dying age-O Colorado squawfish in my study
compared to that of surviving fish confirms that death was
due to exhaustion of energy reserves. Other workers have