Publication Date

2010-06-08

Availability

Open access

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PHD)

Department

Biology (Arts and Sciences)

Date of Defense

2010-04-12

First Committee Member

Kathleen Sullivan Sealey - Committee Chair

Second Committee Member

David Janos - Committee Member

Third Committee Member

Richard Tokarz - Committee Member

Fourth Committee Member

Donald DeAngelis - Committee Member

Fifth Committee Member

Christy Pattengill-Semmens - Outside Committee Member

Abstract

Fish populations are regulated by both external environmental factors, e.g., water quality parameters and habitat, and internal reproductive biology and physiology processes. For many species and populations there is often ample external information, while critical internal, i.e., life-history trait (LHT), information is not available. For this study, I determined LHTs and energy allocation patterns for Epinephelus guttatus (red hind), E. striatus (Nassau grouper), and Mycteroperca venenosa (yellowfin grouper) harvested from The Bahamas. I determined age ranges, and how growth patterns and rates differed among the study species. The maximum ages were: 17, E. guttatus; 22, E. striatus; and 13, M. venenosa. Epinephelus striatus was estimated to have the slowest, while M. venenosa had the fastest growth rate. A gonad histological classification system and the ageing data were used to determine the spawning seasons, sex ratios, size and age of sexual maturation and sex change and gonadosomatic indices (GSIs) for the study species. The peak spawning months were January-February for E. guttatus, December-January for E. striatus and March-April for M. venenosa. The fifty-percent sexual maturity estimates were 235 total length mm (Tlmm) (2.05 year old, yo), 435 Tlmm (4.00 yo), and 561 Tlmm (4.66 yo) for E. guttatus, E. striatus and M. venenosa, respectively. The size and age range of sex change for E. guttatus was between 257-401 Tlmm, ~4-5 years old and between 716-871 Tlmm, ~8-9 yo for M. venenosa. I determined protein and lipid concentrations in muscle and gonad tissues to ascertain energy allocation patterns. For all species and sexes except for female E. guttatus, the proportion of energy delegated to somatic growth declines as a fish grows longer, while reproduction energy allocation increases. The results of each study were compared to previous studies conducted throughout the tropical western Atlantic Ocean, and were related to species-specific ecological and spawning behaviors. The findings of each study highlight that the LHTs of the study species greatly differ and these differences will impact population dynamics and need to be considered for management initiatives. In the final chapter, the effects of fishing on LHTs are reviewed and fishery management options are discussed.

Keywords

Fish Energetics; Fish Reproductive Biology; Fish Growth; Yellowfin Grouper; Red Hind; Nassau Grouper

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