Abstract

The Florida queen conch population has remained in a state of decline, despite a 13-year moratorium on harvest; therefore, stock-enhancement using hatchery-reared juvenile conch is being evaluated. In a successful stockenhancement program, a variety of factors that contribute to maximizing seed survival must be considered. Among these, husbandry techniques must produce seed that are well-adapted to local environmental conditions. Variou... studies have shown that laboratory-reared conch often have less optimal burial responses and lighter sheIl weights than their wild counterparts. We conducted a series of experiments to determine if hatchery-reared conch could develop behavioral and morphological characteristics in the presence of a predator, the spiny lobster (Panulirus argus), that would improve outplant survival. Experiments were conducted in tanks containing a calcareous sand substrate to simulate a natural environment. Conch (35-40mm SL) were exposed to caged lobsters for six hours each day for two weeks; conch in the control tanks were exposed to empty cages. Burial data for the control and conditioned conch were colIected daily. Preliminary results indicate that conchexposed to the lobster buried themselves more frequently than the control group. Morphometric data (shelI length and weight) indicated that predator-induced polymorphisms had occurred. The conch exposed to the lobster grew at a slower rate than the control group, but the sheIl weights of the two groups were not different. This implies that the conditioned conch had thicker sheIls than the control group, perhaps as a predator-induced defense mechanism. Further studies are needed to determine whether these behavioral and morphological modifications will translate to increased survival when the conch are outplanted.

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