Reproductive aspects of Paranthias colonus (Perciformes: Serranidae) on the Pacific coast of central Mexico.

Many species in the family Serranidae are hermaphrodites and of commercial importance. Paranthias colonus belongs to this family, and its reproductive traits are unknown. The present research was carried out with specimens taken from the commercial fishery on the southern coast of Jalisco, Mexico. A total of 1,541 specimens were processed, with an average length of 30.30 ± 0.10 cm and a length interval of 19.80 to 38.00 cm. Specimen gonads were analyzed macro- and microscopically. The sex ratio was 1.00:0.97 (F:M). According to the maximum monthly values of the gonadosomatic index, gonad maturity stages, and oocyte diameters, P. colonus has 2 broad reproductive periods, from March to June and from November to December. A significant correlation was found between the monthly mean values of the gonadosomatic index and the relative condition factor. Gonads in the mature stage had oocytes in 6 different development phases, with diameters that ranged from 14.30 to 417.40 μm, which means that oocyte development is asynchronous. In the testicle, the development of the germ line is of the unrestricted lobular type. This organ did not present the typical arrangement found in teleost fish, since lobes seem to be delimited by lamellae. The information developed in this study indicates that P. colonus is a gonochoric species. Average length at sexual maturity was 26.80 cm for females and 26.90 cm for males. Average catch lengths indicated that 79.70% of females and 83.30% of males had already reproduced at least once before being caught. [ABSTRACT FROM AUTHOR]