Growth, reproductive life-history traits and energy allocation in Epinephelus guttatus (red hind), E. striatus (Nassau grouper), and Mycteroperca venenosa (yellowfin grouper) (family serranidae, subfamily Epinephelinae)

Fish populations are regulated by both external environmental factors, i.e., water quality parameters and habitat, and internal reproductive biology and physiology processes. Internal processes, quantified as reproductive life-history traits (LHTs), vary between species and populations. There is often ample external information, but for many species and populations, critical reproductive LHT information is not available. For this study, I determined reproductive 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. Between the study species, E. striatus was estimated to have the slowest, while M. venenosa had the fastest growth rate. I described a gonad reproductive histology classification system which was used to quantify reproductive LHTs and to identify the reproductive maturity stage of Epinephelinae species. The 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 yo), 435 Tlmm (4.00 yo), and 561 Tlmm (4 66 yo) for E. guttatus, E. striatus and M. venenosa, respectively. The size 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. Females had significantly larger GSIs than males, while some male M. venenosa had atypically large GSIs as compared to other Epinephelinae species. I determined protein and lipid concentrations in muscle and gonad tissues to ascertain growth and reproduction energy allocation patterns. Lifespan growth energy allocation differed between E. guttatus and E. striatus and M. venenosa . The GSI wet weight values (g) were converted to GSI energy values (kJ) and were found not to be equivalent for a given species and sex, emphasizing that caution should be used when interpreting GSI (g) in terms of energy investment. 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 highlight that LHTs of closely related species may greatly differ. Results were compared to previous studies conducted throughout the tropical western Atlantic Ocean, and were related to species-specific ecological and spawning behaviors. In the final chapter, the effects of fishing on LHTs are reviewed and fishery management options are discussed.