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Alternate Title

Comparing the Applicability of Weight-Length Relationships, the Relative Condition Index and Morphometric Criteria to Assess Larval Condition: A Test Case with Striped Bass

Abstract

We compared the applicability of using a weight-length relationship, the relative condition index (Kn) and morphometric criteria to provide insight on the nutritional condition and recruitment potential of larvae of the striped bass Morone saxatilis collected in the Potomac River, MD in 1980-1982 and 1986. Morphometric data indicate that relatively high numbers of larvae In poor condition were present In samples taken prior to mid-May In all years except 1986, but especially In 1980 and 1981. Results of ANCOVA on a subset of data from the first 2 weeks of May In each of the 4 years Indicated significant differences in weight-length regression equations. Larvae In the 1980 and 1981 samples were in poorer condition than in 1982 and 1986, based on regressions coefficients. Estimates of relative condition (Kn) were high in all years except 1986. The morphometric criteria and the regression parameter estimates concurred with an Index of striped bass year class strength, but only after a careful consideration of the assumptions of those condition indices, requiring a reduction in sample size that excluded larger larvae (> 12 mm, morphometric criteria) or averaging data over several larval cohorts (regression parameters).

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