Growth and reproduction of the pelagic goby Sufflogobius bibarbatus off the Orange River, southern Africa

Abstract

Age, growth and reproduction of the pelagic goby Sufflogobius bibarbatus was investigated for males and females caught in demersal trawls between the Orange River and Port Nolloth on the west coast of southern Africa. Females had larger otoliths than males of similar body size, suggesting slower growth rates in females. S. bibarbatus is a large and long-lived gobiid, attaining 13cm at at least 6 years of age, with late maturation at 2–3 years of age. Males were larger than adult females of a similar age and matured at a larger size and greater age than females. Two batches of yolked oocytes were present in the ovaries and the maximum gonadosomatic index was 14.3%. Batch fecundity was significantly correlated with standard length (r² = 0.88) and ovary-free body weight (r² = 0.92), and ranged from about 2 000 eggs in females 5.0–5.5cm long to about 10 000 in a female 9.8cm long. The mean fecundity was 842 ± 189 eggs per gramme of ovary-free body weight. The extended spawning season, from July to April, and the presence of more than one batch of yolked oocytes in the ovaries, suggest that the pelagic goby may be a serial batch spawner.