Observations on the reproductive biology and recruitment of the bigeye grunt, Brachydeuterus auritus (Pisces: Haemulidae), in Ghana
Aspects of the reproductive biology and recruitment pattern of the bigeye grunt, Brachydeuterus auritus (Valenciennes, 1831), are presented in this paper. Data were collected on monthly samples obtained from the artisanal commercial fishery occurring off Cape Coast, Ghana, between November 1993 and October 1995. Both male and female B. auritus appeared to be in better condition just before the minor upwelling (January/February) in Ghanaian coastal waters. In the samples collected, the females outnumbered the males. The length at first maturity was observed as 10.1 cm for both sexes, a size that corresponded to an age of 4 months. The length at massive maturation (L50%) was, however, estimated at 14.8 (= 9.1 months) and 15.1 cm (= 9.5 months), for the males and females, respectively. The oocyte diameter distributions suggested restricted spawning in the species. The occurrence of ripe fish in all the samples, however, is an indication of protracted spawning. Although individuals were ready for spawning throughout the year they probably spawned during the upwelling seasons. In the species, recruitment occurred throughout the year, but with two pulses of unequal strength, with the major recruitment occurring just before the upwelling periods.