Date of Award

Spring 5-2018

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)

Committee Chair

Robert T. Leaf

Committee Member 2

Dr. Eric N. Powell

Committee Member 3

Eric Robillard

Abstract

Recent efforts to manage Atlantic Chub Mackerel (Scomber colias) in the northwest Atlantic have necessitated the description of the stocks life-history characteristics. The purpose of this study was to address the absence of regional information on growth and reproduction. Growth models were fit in a Bayesian framework. The length-at-age relationship was described using four non-linear candidate growth models, which were fit to total length (TL, cm) and age estimates (y). Age estimates were derived from whole otoliths for adults (n = 422) and ages of one month were assigned to larval fish (n = 60). The three-parameter VBGF was selected as the best candidate model using Deviance Information Criterion = 33.56 cm TL, k = 1.75 y-1, t0 = 1,136) to describe the weight-at-length relationship (a = 0.0258, b = 2.72). Sex and maturity were evaluated using histological techniques. A two-parameter logistic function was fit to length measurements (cm) and maturity estimates (n =151) to describe length-specific maturity for females (r = 0.38 cm-1, L50 = 27.39 cm TL). Age-at-50% maturity was estimated as 2.16 (y) by back calculation. Spawning season was estimated to occur during the months of January to April, using histological indicators and evidence of spawning from analysis of historical data on larval fish collections and commercial catch. These results can be used to inform the effective management of the Atlantic Chub Mackerel stock in the northwest Atlantic.

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