Biological Studies of the Spiny Lobster, Panulirus argus (Decapoda; Palinuridae) in South Florida

Warner, Richard; Combs, Christopher; Gregory, Douglas

In recent years, the commercial fishery for spiny lobster (Panulirus argus) in Florida has ranked second only to the shrimp fishery in economic importance. With increased fishing pressure, the catch per unit of effort has declined, causing significant profit losses to lobster fishermen. The present study was designed to examine the seasonal movements, reproductive biology, growth rates, population structure, distribution, and relative abundance of local adult and sub-adult populations of spiny lobster, especially as these parameters relate to the commercial lobster industry. Overt reproductive activity, as evidenced by spermatophore or eggs, was observed in 14.9% of 1,591 females captured on or outside the deep offshore reef-line in the Atlantic. Reproductive activity, however, was negligible among 697 females trapped and tagged in the shallow Gulf. Analysis of arbitrarily selected sub-samples of recaptured tagged lobsters indicated that non-reproductively active animals in the shallow Gulf moved generally west-southwest toward the Atlantic reef-line and deeper waters. These movement patterns, and observations on reproductive condition in these and previously studied Gulf females, preliminarily suggested that the large numbers of Gulf-captured lobsters do not exercise their reproductive potential. In the Atlantic, long-distance movements of lobsters (greater than 8 km) are eastward (predominant) and westward along the reef-line. Shorter distance (less than 8 km) and inshore-offshore movements have not yet been analyzed. Maximum movements by lobsters were 107 km (58 n. mi) in the Gulf (40 km average), and 37 km (20 n. mi) in the Atlantic (17 km average). Mean carapace length of 2,666 lobsters, captured in commercial wooden slat traps during the 1975-76 season (August 1, 1975- March 31, 1976), was 72.9 mm, or 3.3 mm below the minimum legal size (76.2 mm or 3 in); the mode was 68.5 mm, or 7.7 mm below the minimum legal size. Only 37% of all animals sampled were of legal size or larger. The south Florida commercial fishery is stressed heavily in both the Gulf and Atlantic. A re-evaluation of the current management program for the lobster resource in south Florida is necessary to insure the perpetuation of the fishery.

Biological Studies of the Spiny Lobster, Panulirus argus (Decapoda; Palinuridae) in South Florida

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