Environmental intervention in the reproductive process of the American lobster,Homarus americanus

Abstract

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 schedule 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 ( H o m m ammicanus), 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 JanuaryJune) by inducing spawning with unseasonably high temperature (13°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 "C) .

Expression of the crustacean hyperglycaemic hormones and the gonad-inhibiting hormone during the reproductive cycle of the female American lobster Homarus americanus

“…The higher CHH-A and -B neuropeptide storage levels in the sinus gland during previtellogenesis than during vitellogenesis was not reflected in the total CHH content of the haemolymph and may therefore indicate that the peptides are released during late previtellogenesis or at the onset of vitellogenesis. Such a higher release of CHH-A and -B would trigger vitellogenesis during autumn and would be in agreement with the hypothesis of Waddy & Aiken (1992) that, before winter, females only rarely respond to environmental changes. However, in early November, most females respond to artificially changed day length and temperature by spawning 3 months later.…”

“…As the lobster has a biannual reproductive cycle, these females would be mature and would spawn normally in the summer of 1995. However, artificial induction of spawning by the method of Waddy & Aiken (1992) permitted the different reproductive stages to be obtained at an earlier period. The reproductive condition of each female was confirmed by examining the pleopodal cement glands in early spring 1994, and all animals selected were kept in vertically stacked tanks with plexiglass front panels so that spawning could be observed without disturbing the animals.…”

Reproductive strategies of the spiny lobster Panulirus interruptus related to the marine environmental variability off central Baja California, Mexico: management implications

“…The present paper provides evidence of the importance of environmental factors in the timing of reproduction in P. interruptus, as has been documented for other lobsters (Nakamura, 1994;Kittaka and MacDiarmid, 1994;Waddy and Aiken, 1992;Waddy et al, 1995). The timing of breeding is temperature dependent.…”

“…Among various environmental factors, temperature is the major factor controlling reproduction in lobsters (Aiken and Waddy, 1980;Quackenbush, 1993;Chubb, 1994;Waddy and Aiken, 1992;Waddy et al, 1995). It has been suggested that warmer temperatures significantly accelerate reproduction in P. cygnus, P. argus and P. japonicus (Lipcius and Herrnkind, 1987;Nakamura, 1994;Kittaka and MacDiarmid, 1994).…”

Estimating spatial distribution of American lobster Homarus americanus using habitat variables

“…Cowan et al (2007) suggested that tagged ovigerous lobsters attempted to occupy water with consistent rather than high temperatures. Moreover, a low water temperature that is below 8°C or even 5°C may be required for ovarian development, which will affect the onset of the next brood (Waddy & Aiken 1992). Adult females must balance the tradeoff between optimizing growth and promoting reproduction instead of simply residing in areas of high water temperatures to optimize growth.…”