Date of Award

Spring 5-2017

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)

Department

Ocean Science and Technology

Committee Chair

Robert T. Leaf

Committee Chair Department

Ocean Science and Technology

Committee Member 2

Mark S. Peterson

Committee Member 2 Department

Ocean Science and Technology

Committee Member 3

Nancy J. Brown-Peterson

Abstract

Vermilion Snapper is a commonly harvested species of reef fish in the northern Gulf of Mexico (GOM). It supports both a large commercial and popular recreational fishery, however knowledge of this fish’s life history is limited spatially. Non-linear curve fitting was used to estimate growth parameters and Akaike information criteria (AIC) was used to determine relative model fit. The 2-parameter von Bertalanffy growth function provided the best model fit and lowest AIC score. Histological examination indicated that Vermilion Snapper are batch spawners with asynchronous oocyte development. Additionally, 17% of Vermilion Snapper in the actively spawning phase containing 24 hour POF’s suggesting daily spawning is occurring. No immature fish of either sex were collected during this study (139 mm to 535 mm TL). Both histologically-determined phases and gonadosomatic index (GSI) patterns defined the spawning season ranged was from April to September. The spawning interval for Vermilion Snapper was estimated using the hydrated oocyte and post-ovulatory follicle methods, was 1.8 and 2.2 days respectively. Batch Fecundity (BF) estimates of 5,497 to 284,468 eggs/batch were determined using fish macroscopically classified as actively spawning (n = 22). Total fecundity (BF by spawning frequency) was estimated to range from 544,203 eggs/spawning season up to 28,162,332 eggs/spawning season. Mean relative batch fecundity was 70.7 eggs/g of gonad-free body weight. Estimates from this study can be directly incorporated into population assessments and provide a region-specific overview of life-history for the Vermilion Snapper from the north-central Gulf of Mexico.

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