Population features of Microphrys bicornutus, Latreille, 1825 (Brachyura, Majidae) from Isla Margarita, Venezuela.

LÓPEZ GRECO, L.S., HERNANDEZ, J.E, BOLAÑOS, J., RODRÍGUEZ, E.M. Y G. HERNÁNDEZ.

HYDROBIOLOGIA

KLUWER ACADEMIC PUBLISHERS

Año: 2000 vol. 439 p. 151 - 159

0018-8158

The aim of this study is to characterize the population biology (sex ratio, size structure, relative growth of reproductive characters and realised fecundity) of the crab Microphrys bicornutus from Isla Margarita, Venezuela. Nearly 100 crabs were collected and fixed monthly during 1998. In the laboratory, crabs were sexed and measured: maximum carapace length, chelae length, chelae and abdomen width for females and first pleopod length for males. Additionally, 96 ovigerous females were collected to determine fecundity. The following measurements were taken for each female: body wet weight (BWW), body dry weight (BDW), egg wet weight (EWW), egg dry weight (EDW) and number of eggs (NE). The following determinations were made: relative fecundity (RF)=NE/BDW and reproductive output (RO)= EDW/BDW)x 100. Relative size at the onset of maturity (RSOM) was calculated as minimum ovigerous female/female´s maximum size. The results indicate that the sex ratio is nearly 1:1 during the entire year. Ovigerous females and moulted males and females were observed throughout the year. Size frequency distribution and size at the onset of sexual maturity, estimated by relative growth of the sexual secondary characters and RSOM value, differed from those estimated in studies done in Jamaica and Buchuaco, Venezuela.