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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12

Percent survival was calculated for all three size
classes and feeding regimes on a daily basis throughout the
210-day winter period. Percent survival was calculated by
dividing the number of fish in a given size class and
feeding regime that were alive at the end of each day by the
original number of fish minus the number removed for lipid
analysis on days 70 and 140.
Due to their small size, several fish from each size
class and feeding regime had to be pooled to provide enough
material for lipid extraction. Approximately 11 small fish,
8 medium, or 4 large fish were pooled to provide sufficient
material for each extraction. Lipid analysis was performed
as follows. Frozen fish weighing 1-2 g (wet weight obtained
prior to freezing) were placed in an aluminum drying pan.
Fish were dried at 90-1000 C for 20-24 hours. After cooling
for 24 hours in a desiccator, dried fish were reweighed, and
percent water was calculated. Dried samples were finely
ground with mortar and pestle and placed in cellulose
extraction thimbles. Each thimble and its ground sample was
redried for 20-24 hours, cooled in a desiccator, and weighed
to 0.0001 g. Samples were extracted on a GoldfisctlID fat
extraction apparatus for 6-7 h with di-ethyl ether. The
precision of the lipid-extraction technique was tested by
running several analyses on large (3-4 g) homogenized
samples of non-experimental fish. In all cases, the
calculated lipid values were within 4% of each other. The