| General Species Description: |
Reproduction Comments:Olsen and LaPlace (1978): spawning aggregations occurred in St. Thomas from November to February at a point on the 100 fathom curve 8 miles south of St. Thomas; aggregation was conical from bottom (50 m) to 20 m depth; about 2,000 individuals were present. Tucker (1992): aggregations began several days before full moon at 27 m depth, then moved to 35 m depth after the full moon; spawning occurred 6-9 days after full moon. Smith (1972): aggregations at Cat Cay and Great Isaacs, Bahamas around the middle to late January; 30,000-100,000 indidivuals observed in the aggregation. Colin et al. (1987): aggregations observed at Grand Cayman, Little Cayman, and Cayman Brac; over 1,000 were caught by fishermen at the Little Cayman site. Smith (1958): spawns from May to August in Bermuda. Carter (1988): gathers to spawn during the first full moon of the year; spawns in December and January at Rocky Point, Ambergris Cay. Tucker and Bush (in press): most spawning occurred 6-9 days after the full moon. Tucker et al. (1993): spawning aggregations in January and February (1987-1992) in the Cayman Islands; began aggregating between first quarter and full moon and spawned between 2 days before and 10 days after full moon.
Individuals may live for 20 years, attaining sexual maturity at 500 mm total length (1.87 kg) and more than 5 years of age (Sadovy, in press). Females change to males at a size of 30-80 cm total length (Jory and Iversen 1989). Growth rates of individuals measuring 175-250 mm, 251-325 mm, and 326-450 mm total length are 4.55 mm/month, 3.5 mm/month, and 1.92 mm/month, respectively (Randall 1961). Fecundity increases exponentially as a function of weight (Olsen and LaPlace 1978). Intense fishing of spawning aggregations can lead to increases in the female to male ratio, potentially leading to reproductive failure (Colin et al. 1987, Carter et al. 1990). Thompson and Munro (1983b): sex ratio of males to females in an unexploited area was 1:0.72.
Shenker et al. (1993): 1,302 of 10,376 larvae caught in channels of Exuma Sound were Nassau grouper; larvae recruit onto Bahamas Bank through channels in discrete pulses during early January; over 86 percent of the recruitment occurred as a result of one storm event with onshore winds; individuals in the recruitment pulse averaged 23.4 mm SL (18-30 mm range).
Ecology Comments:Sullivan and de Garine (in press): moves more than 20 m away from home reef 65 percent of time; home range size is greater than 500 square meters. Beaumariage and Bullock (1976): when collected at one reef and transported to another in close proximity, individuals returned to original reef. Bardach (1958): show strong homing tendencies.
Tends to be site-specific but has a larger home range than do smaller grouper species (Bardach 1958, Beaumariage and Bullock 1976, Sullivan and de Garine 1990, Beets and Hixon 1994, Sluka and Sullivan 1996a). Randall (1961) reported that some move distances of 1-10 miles after tagging.
May suffer high post-settlement predation (Beets and Hixon 1994). Sea water temperature has pronounced and direct effects on feeding and growth of juveniles; timing of spawning in relation to seasonally changing temperature may be important in determining juvenile growth rates, vulnerability to predation, and, hence, year-class strength (Ellis et al. 1997).
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