Using diver surveys, we compared the size structure, fecundity, and
reproductive season of spiny lobsters (Panulirus argus)
in the Dry Tortugas National Park lobster sanctuary with those of spiny
lobsters in the south Florida fishery. The number of lobsters of both sexes
larger than the legal size limit declined sharply in the fishery but not in
the sanctuary. Clutch sizes were larger in the Dry Tortugas sanctuary,
averaging 0.8 million, than in the fishery, averaging 0.3 million. The
reproductive season was shorter and more intense in the sanctuary than in the
fishery. In addition, lobsters in the sanctuary begin producing eggs at a
larger size and produce more eggs per gram of body mass than lobsters in the
fishery. Peak egg production occurs earlier in larger lobsters than in small
ones. Establishing a fundamental reason for the differences between lobster
reproduction in the sanctuary and that in the fishery is not possible until
the chronological age of lobsters can be determined, but one hypothesis
consistent with these differences is that, if lobsters reproduce at a certain
chronological age, then sublethal fishery practices may account for slower
growth for some lobsters resulting in some smaller but older reproductively
active lobsters.
Loss of Structural Complexity in Staghorn Coral Rubble Habitats Influences the Density of Damselfish in Dry Tortugas National Park, Florida, USA
