Abstract

The Queen conch Strombus gigas is a marine resource of economic, social and cultural importance in the Caribbean countries Total conch production reached 6,520 in 1993 and was reduced to 3,132 tons in 2003. North American market absorbs 80% of this registered production, 17% is exported to the French islands and 3% is consumed in the others Caribbean countries. The high fishing pressure in most Caribbean countries has caused the reduction of the populations of S. gigas, forcing to the establishment of regulatory measures. Studies of the reproductive cycle of S. gigas are necessary to regulate this resource in the Caribbean region. The present study shows the correlation between the lip thicknesses of Strombus gigas versus the reproductive cycle. 700 organisms were sampled at San Andres (Colombia) in 2003; they were sorted in three groups: a) 10 - 17 mm shell total length, without lip; b) Shell total length ? 170mm and lip thickness <5mm and c) Shell total length ? 170 mm and lip thickness > 5 mm. Samples of visceral mass and gonad were processed by standardized histological methods. Only undifferentiated stages were observed for organisms of 100 - 170 mm of shell length, without lip. Organisms ? 170 mm of shell length with a thin lip showed undifferentiated stage throughout the year and a low initial gametogenesis in April-June and October-January, (? 20%). The group of shell length ? 170 mm and lip thickness > 5 mm exhibits a very different behavior; it undergoes a whole reproductive cycle with gametogenesis during most of the year and spawn in January-February for females and from September to February for males. However mature and spawn stages are very short and represent a low proportion of the population. According to this study, the minimal catch size does not appear as mandatory; the existence of a thin shell lip is neither an efficient criteria of sexual maturity. Only a lip thickness > 5 mm appears as a maturity criteria. Therefore, it appears necessary to introduce this criteria corresponding to a lip that may not be broken by hand, in Caribbean countries regulations. A temporal ban from 1st May to 30 September seems to be well fitted to protect the main reproduction period and to protect the reproductive stock. To be efficient these regulations have to be applied in all the Caribbean countries and to be included in the CITES regulations for exportation. However, the level of protection will depend on a high enforcement of regulations to control exploitation and reduce illegal fishing.

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