Estudi de la fecunditat i estratègia reproductiva de Serranus Cabrilla (Pisces, Serranidae)

Abstract

The teleost and benthic fish studied, the Serranus cabrilla, colloquially called serrano, is a functional simultaneous hermaphrodite fish and presents ovotestis. During the breeding period produce and mature sperm and eggs simultaneously. It is the only genus that presents this type of hermaphroditism in the Mediterranean. The objective of this study is to provide new information about the reproductive strategy of Serranus cabrilla as spawning season, fecundity and if the self-fertilize likely or not. It was collected during April and May 2016 in different parts of the Costa Brava; its total length varied between 147mm and 233mm, and the standard length varied between 116mm and 194mm. The methodology used was: histological observation of the gonads, calculation of indices related to reproduction and finally evaluation of fecundity. Testicular tissue occupies less space within the gonad compared to ovarian tissue, which has an asynchronous development: oocytes coexist in different stages of development. From the HSI has not been observed that there is a remarkable accumulation of lipids in the liver previous to oocyte maturation. Testicular tissue begins to mature in February and ovarian tissue during the month of March, when we begin to observe vitellogenic oocytes with a greater diameter than 200μm. The spawning season of the Serranus cabrilla is in May and June, since we are observed hydrated oocytes and postovulatory follicles. In addition there is an increase of the GSI between April and May and then stabilizes in June, corroborating the beginning and continuation of the spawning between May and June. The spawning of Serranus cabrilla is asynchronous. Mature and viable oocytes released into the medium have a diameter greater than 500μm. The average fecundity of the Serranus cabrilla is 6.445 eggs during the spawning season where the range varies between 1.200 eggs to 22.072 eggs and the potential fecundity is of 10.551 eggs. Self-fertilization in Serranus cabrilla is unlikely; everything seems to indicate that they release the gametes sequentially and only when they have found an individual with whom to mate