Reproductive strategies of sea basses based on larval abundance in magdalena bay, Mexico, 1982-1986

We analyzed the reproductive strategies of four sea basses Paralabrax spp. based on larval abundance and sea surface temperature during a period affected by the El Niño of 1982-1983. Zooplankton samples were taken monthly in the Magdalena-Almejas lagoon complex of Baja California Sur, Mexico, from January 1982 to November 1986. Larvae of four sea bass species were recorded; those of the spotted sand bass P. maculatofasciatus were dominant, contributing 43% of total abundance. Barred sand bass P. nebulifer constituted 28% of the sampled larvae, goldspotted sand bass P. auroguttatus contributed 26%, and kelp bass P. clathratus made up 3%. During 1983-1984, the larval abundances of spotted sand bass and goldspotted sand bass decreased (by >50% and 90%, respectively), while the abundance of barred sand bass increased by nearly 25%. A seasonal larval abundance maximum for all species was recorded in summer and autumn, but a differential reproductive pattern inferred from larval abundance was determined. Spotted sand bass showed continuous reproductive activity with peaks in February, June, August-September, and November. Barred sand bass larval abundance indicated one reproductive period with peaks in June and November; a single reproductive period (August) was found for goldspotted sand bass. The abundance of kelp bass larvae was very low, and we were not able to identify a reproductive pattern. Spawning habitat occurred at the relatively narrow temperature range of 19-24°C for spotted sand bass and at 24-28°C for barred sand bass; the widest range was recorded for goldspotted sand bass (22-29°C). The temporal segregation and the differences in spawning habitat permitted the identification of three different reproductive strategies in which there exists a certain degree of overlap. This study represents a first step in understanding the reproductive cycle of three species of sea basses in Magdalena Bay.