Reproductive Strategies of Sea Basses based on Larval Abundance in Magdalena Bay, Mexico, 1982–1986

Abstract

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.