Date of Award
Spring 5-2007
Degree Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Coastal Sciences, Gulf Coast Research Laboratory
Committee Chair
Dr. Bruce H. Comyns
Committee Chair Department
Coastal Sciences, Gulf Coast Research Laboratory
Committee Member 2
Nancy Brown-Peterson
Committee Member 2 Department
Coastal Sciences, Gulf Coast Research Laboratory
Committee Member 3
Dr. Terry Henwood
Committee Member 3 Department
Coastal Sciences, Gulf Coast Research Laboratory
Committee Member 4
Dr. Jeffery Lotz
Committee Member 4 Department
Coastal Sciences, Gulf Coast Research Laboratory
Committee Member 5
Dr. Chet Rakocinski
Committee Member 5 Department
Coastal Sciences, Gulf Coast Research Laboratory
Abstract
Age, growth and reproduction research was conducted on yellow edge grouper, Epinephelus flavolim batus, obtained from the commercial harvest and National Marine Fisheries Service scientific cruises in the Gulf o f Mexico (GOM) during 1979-2005. Fish ranged in size from 107-1,170 mm total length (TL). Ages ranged from 0 to 85 years; maximum age greatly exceeded previously reported ages. Bomb-produced 14C was used to validate ages determined by counting otolith growth increments. A strong linear relationship existed between otolith weight and fish age (R2 = 0.84). The von Bertalanffy growth equation was TL=970.8(l-e"° 063(1+4 84)). Length and age structure yellow edge grouper harvested today are considerably smaller and younger than those in the past. Yellow edge grouper are monandric protogynous hermaphrodites and have an extended spawning season from March through September. Results indicated a change in the sex ratio over the last 25 years due to a 14% decrease o f males. Size at sexual maturity and size at transition have also decreased.
Yellow edge grouper were distributed throughout the GOM, but regional differences in population density, size and age structure and sexual maturity suggest at least two or three separate stocks occur in the GOM. Yellow edge grouper in the western GOM were larger, older and more abundant while fish in the eastern GOM were smaller and younger. Yellow edge grouper in the eastern GOM aggregate in denser patches than those in the western GOM.
Yield-per-recruit and spawning stock biomass-per-recruit analyses were applied to determine biological reference points and evaluate the status o f the fishery. Results indicated stocks cannot sustain high levels o f fishing mortality (F
Copyright
2007, Melissa Cook
Recommended Citation
Cook, Melissa Bahnick, "POPULATION DYNAMICS, STRUCTURE AND PER-RECRUIT ANALYSES OF YELLOW EDGE GROUPER, EPINEPHELUSFLA VOLIMBATUS, FROM THE NORTHERN GULF OF MEXICO" (2007). Dissertations. 1241.
http://aquila.usm.edu/dissertations/1241