Abstract

Since 1997, between February and April, fishermen from the state of Yucatan have been capturing large amounts of yellowfin grouper Mycteroperca venenosa from "Bajos del Norte" on the Campeche Bank. This area, located at 130 knots north of the Yucatan coast, is conformed by numerous shallow coral reefbanks (520 m depth). From February 4 - 13, 2001, a trip to "Bajos del Norte" was undertaken aboard a fishing boat with the objective to study a probable spawning aggregation of M. venenosa. For this purpose, direct and indirect methods (SCUBA diving observations and fish sexual development stages determined by histological analysis of gonads) were used. Eight species from the genera Cephalopholis, Epinephelus and Mycteroperca were identified by visual census and/or through the capture done by fishermen. No typical spawning aggregation activity was observed during SCUBA diving. Not with standing, the groupers catch done dwing the five days of fishing, reached a total of 2,435 kilograms. The more abundant species in the whole catch were Mycteroperca venenosa, Epinephelus guttatus, M. tigris and M bonaci. The majority or total of females and males, which gonads were analyzed, were sexuallyactive. For females, hyaline oocytes or postovulato¡y follicles were not observed. However, oocytes in late secondary vitellogenesis were noted in ovaries of 100% E. guttatus females, 64% of M. venenosa females, 75% of M. bonaci females and 58% of M. tigris females. More than 98% of analyzed males were sexually active. More studies are necessary to confirm the formation of groupers spawning aggregations in this region and to con tribute to the management of this commercial high value resource.

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