The Environmental and Hormonal Control of Growth and Reproduction in the Adult Female Stone Crab,menippe Mercenaria(say)

The effects of certain environmental and physiological factors in the growth and reproduction of adult female stone crabs, Menippe mercenaria (Say), were studied between April, 1965 and November, 1967 by employing a long-term rearing method. The crabs were kept isolated from one another in tanks supplied with constantly running sea water pumped almost directly from Biscayne Bay and were fed daily with pink shrimp meat.2. Results showed that spawning was most frequent in warm temperature, indicating that the seasonal dependence of spawning may be related to seasonal temperatures. Molting occurred most frequently in autumn-winter, a period of decreased spawning, although summer temperature seemed more favorable to molting. Summer molting may therefore be inhibited by reproductive activities.3. In order to study the control of molting and spawning, several experiments involving the destalking of crabs were performed in a 13-month period. Destalking in August and September of 1966 induced molting. After September, crabs responded to destalking either by molting or by spawning. As the year progressed, the proportion of spawning to molting crabs increased until in September, 1967 spawning was the only response. This finding not only supported the work on Gecarcinus lateralis (Weitzman, 1964) in that there was a cyclic change in the dominance of molting and spawning, but also indicated a transitional period between the periods when molting or spawning are dominant.4. The effect of destalking postmolt crabs was studied. The results indicate these crabs spawn precociously, but do not undergo accelerated ovarian development. This indicates that spawning and ovarian development may be controlled by different hormones.