SFRC-83/02 Population Structure, Food Habits, and Spawnig Activity of Grey Snapper, Lutjanus griseus, in EVER

Rutherford, Edward; Thur, Edith; Buker, David

Population structure, food habits, and spawning activity of 1026 gray snapper, Lutjanus grIseus, were studied in Everglades National Park from November 1978 through January 1980. Fish were sampled from sport fishermen catches and ranged in length from 111-451 mm F.L. (x = 257:t 3.2 mm) and in weight from 0.05-1.6 kg (x = 0.33 :t .02 kg). There was no difference in mean length between sexes. Fish aged from scale annuli ranged from one to seven years. Two- and three-year old fish dominated the catch. Recruitment was complete by age three. The mean age of all fish was 3.0 + 0.1 yrs. There was no difference in mean age between the sexes. Fish taken from the Cape Sable area were significantly older than fish taken from other areas. Calculated growth of gray snapper was greatest in the first year and relatively linear before increasing in the fifth year. Calculated growth varied between sexes and among areas of capture. Females were significantly larger than males at ages one and two. Fish taken from hypersaline areas near the Gulf of Mexico were larger at ages one through four than fish taken from seasonally brackish waters. Males in the Shark River area did not show as great an increase in weight with length as did all fish in other areas. Females in the Coot Bay and Whitewater Bay area were heavier at a given length than all fish in other areas. Annual survival rate of all fully recruited fish was s = 0.28 + .03. Survival of males was higher than females. Gray snapper survival was higher in the hypersaline waters near the Gulf than in other areas.

SFRC-83/02 Population Structure, Food Habits, and Spawnig Activity of Grey Snapper, Lutjanus griseus, in EVER

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