Age, growth, and reproduction of scamp, Mycteroperca phenax, in the southwestern North Atlantic, 1979–1997
Scamp (Mycteroperca phenax) is a protogynous grouper that is a popular commercial and recreational species along the Atlantic coast of the southeastern United States. Scamp were sampled from the commercial and recreational fishery (1979–1996), and from the Marine Resource Monitoring Assessment and Prediction (MARMAP) program, a fishery-independent sampling program (1979–1997). Ages were determined from transverse sections for 2573 of the 3142 scamp for which we had otoliths (82%), and 2470 gonads were examined histologically. Data from all data sources were pooled, and trends between two periods, 1979–89 and 1990–97, were examined. Median length decreased significantly from 610 mm TL in 1979–89 to 570 mm TL in 1990–97, although there were no significant differences in the median age, size at maturity, and age at maturity between periods. The percentage of males declined from 34% to 21% for specimens >500 mm TL, although the sample size was much smaller during the earlier period (336 vs 1645). The percentage of scamp age 10 and older declined from 17% in 1979–89 to 7% in 1990–97. Females spawned from late February through mid-July, with a peak during March through May. Fishery-independent sampling revealed that: (1) spawning probably occurred during the late afternoon and evening, and (2) higher proportions of scamp spawned around new moon and full moon. The relationships between batch fecundity and TL, FL, ovary-free body weight, and whole body weight were highly significant. Potential annual fecundity is indeterminate and was estimated to range from 1,313,000 to 10,503,200 oocytes in specimens 445–712 mm TL. The wide ranges of size and age at sex transition and the temporal distribution of transitionals suggest that sex transition is socially mediated. The decrease in the percentage of males, and reduction of egg production caused by the loss of older, larger females from the population suggests scamp may be increasingly vulnerable to continued overexploitation. A spawning season closure on the fishery for gag may result in a further increase of the exploitation of scamp, requiring close monitoring of the population for the foreseeable future.
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Document Type: Research Article
Publication date: 2002-01-01
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