ENVIRONMENTAL INTERVENTION IN THE REPRODUCTIVE PROCESS OF THE AMERICAN LOBSTER, HOMARUS-AMERICANUS

The efficient culture of an animal requires a reliable year-round supply of seed. However, in most species knowledge is insufficient for the degree of broodstock control required to sehedule seed production throughout the year. Although it has been relatively easy to identify the regulatory parameters in some species, in many others it has been difficult. In the American lobster (Homarus americanus), controlling mechanisms are complex: responses to temperature and photoperiod vary with environmental history and season, and shifting the onset of a temperature increase by only a few days can produce entirely different responses. After two decades of experimental work, we have finally developed a broodstock system that produces synchronous and predictable spawning as required. Two strategies are used to produce year-round seed from a stock that normally spawns in July: (1) spawning is achieved throughout the winter and spring (late January-June) by inducing spawning with unseasonably high temperature (13-degrees-C) and short photophases (LD 8:16); and (2) spawning is achieved through the late summer and autumn (August-December) by delaying spawning with low temperatures (1-2-degrees-C).