Relationship of Lipid
Content to Size and Condition in Walleye Fingerlings from Natural and
Aquacultural Environments
T. Copeland, R.F. Carline-2004
North American Journal of Aquaculture, 66(3):
237–242
Abstract:
Condition indices are widely used in the evaluation
of fish populations, but most research on the relationship of condition
indices to body composition has taken place in laboratory environments. Our
objectives were to assess the relative ability of measures of size and three
versions of condition index to predict the lipid content of fingerling
walleyes Sander vitreus from aquacultural or natural environments.
Fingerlings were either intensively cultured through the fall of 1994, were
stocked and spent 3–4 months at large in four lakes, or were intensively
cultured and maintained overwinter in hatchery ponds. Variation in condition
indices accounted for less than 35% of the variation in lipid. No index
performed substantially better than the others. The relationship of
condition to lipid content was not consistent between environments or
seasons (ANCOVA: F = 403.4, P < 0.0005). Relationships were
also different among the four lake populations (ANCOVA: F = 33.9, P
< 0.0005). Inconsistencies seem to be the result of differences in
seasonal and environmental stress. The utility of condition indices as
surrogates for body composition should be verified with each use.
Furthermore, comparisons of fingerlings from aquacultural environments with
fingerlings from natural environments are unlikely to be physiologically
meaningful
(Pennsylvania Fish and Boat Commission, Box 88, Sweet Valley,
Pennsylvania 18656, USA)