Reproductive biology of Mulloidichthys dentatus (Perciformes: Mullidae) in the mexican tropical pacific

Abstract

-Although Mulloidichthys dentatus is a commercially important species in this region of the Mexican Pacific, most aspects of its biological life cycle, including reproduction, are not known. The main goal of this study was the description of several reproductive traits of M. dentatus in the southern coast of Jalisco, Mexico. Monthly sampling was carried on from January 1998 to December 2008. Fish were caught using a set of gill nets with different mesh sizes. A total of 1,590 individual were sampled and total length (TL), total weight, sex and maturation stage were determined for each fish. Gonads were extracted and preserved for histological analyses. Minimum, mean and maximum TL of fish sampled were 16.5, 30.9 and 40.0 cm, respectively. A total of 899 females and 691 males were collected with the overall sex ratio equal to 1.3:1. Maximum values of gonadosomatic index (GSI) and mean oocyte diameter, as well as the percentages of gonads in advanced reproduction stages suggest that M. dentatus has three main reproductive periods in March, May-July and November. Significant correlation between both sexes was found for GSI and condition factor. Seven oocyte development phases were found in ripe ovaries, which suggest asynchronic oocyte development. Cell arrangement found in testis was of lobular type with an externally well-defined sperm duct. Maturation length was 25.4 cm for females and 24.5 cm for males. As these values are less than the mean lengths observed in catches (31.9 and 29.7 cm TL), it can be assumed that more than 50% of caught individuals have had a reproductive event (99% female and male).