An evaluation of Lake Michigan alewife aging methodologies, growth, and stock separation

Abstract

Ageing methodologies of Lake Michigan alewife were evaluated as a precursor to growth and condition investigations of alewife stocks. Four commonly used aging tissues were evaluated including: otoliths, scales, vertebrae, and opercles. Otoliths were significantly more precise than other structures in all analyses. The accuracy of age determinations given by otoliths was corroborated through length frequency analysis. Total processing time was highest for scales. Whole otolith methodology was used to age alewives from Indiana, Michigan, and Wisconsin based on precision, accuracy, and time efficiency. A trend of higher median lengths and weights in young fish from the Green Bay, Wisconsin site was identified. Older fish grew faster in the main-lake sample sites near Pentwater, Michigan and Indiana waters. The Indiana population had the highest condition factor (K), while Wisconsin had the lowest, with Michigan in between. An overall temporal decline in condition of alewife was identified when compared with historical studies. This is a consideration that may influence salmonid stocking decisions because the alewife serves as their primary food.Department of BiologyThesis (M.S.

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oai:cardinalscholar.bsu.edu:handle/188036Last time updated on 6/25/2012

This paper was published in Cardinal Scholar.

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