Calamus brachysomus, commonly known as Pacific porgy, is the only member of the Sparidae family that inhabits the Gulf of California. In Baja California Sur (BCS), its catch has increased in the last years. It has previously been considered as a candidate for aquaculture, which increases the need to know basic aspects of its biology. The objective of this research is to describe their reproductive cycle and obtain the gonadosomatic index from samples obtained from Santa Rosalía, BCS.
From July 2015 to July 2016, specimens were captured monthly for a total of 265 samples (147 females and 118 males). From these, the gonadosomatic index (GSI=gonad weight/body weight) was obtained. In addition, 1 cm3 sections of the gonad were analyzed by histological techniques to obtain the reproductive cycle.
Females measured between 16.5 and 36.5 cm TL (mean ± standard deviation, 24.5 ± 3 cm), and males measured between 15 and 37 cm TL (24 ± 3.1 cm). Capable spawning females were identified in 11 of the 13 months analyzed. This extended spawning period coincides with the reported for other members of the family Sparidae. The GSI trends showed a peak from May to July in both sexes, which coincided with the highest percentage of organisms with spawning capacity. This suggests that the GSI is a reliable indicator to monitor maturation events in this species. The peak of reproductive activity was found at a sea surface temperature of 21 to 28 °C.