Seasonal and interannual variability in wind field and commercial catch rates of austroglossus pectoralis (soleidae)

The impact of deviations in the direction and strength of the wind field on the spatial, seasonal and interannual variability in catch rates of Agulhas sole Austroglossus pectoralis was investigated. Temporal variabilityin the wind cycle on the Agulhas Bank during the period 1981–1996 was deduced mainly from trends in the pressure gradient, measured from south of Cape Agulhas (35°S) to the region of westwind drift (40°S).Because interannual deviations in the catch rates differed between seasons, catch rates were assessed by season. Coastal catch rates of Agulhas sole between Cape Agulhas and Cape Infanta were high in autumn and winter, when offshore north-westerly winds prevailed, and low in spring and late summer, when onshore south-easterly winds dominated. There was often a secondary peak in catch rates in November–December,coincident with a midsummer change in the pressure gradient. Between the period 1982 and 1996, catch rates in autumn and early winter (April–July) were highest during years when the winter north-westerly winds were strongest (r2 = 0.62, p < 0.01). Catch rates usually peaked in May–June. This pattern changed in some years, depending on the timing and rate of change to winter wind conditions. Seasonal and interannual fluctuations in catch rate are associated with deviations in the wind field, but the  mechanism whereby this  effect is mediated remains unknown

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

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&#37. Batch fecundity was significantly correlated with standard length (r2 = 0.88) and ovaryfree 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 &#177 189 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. African Journal of Marine Science 2005, 27(1): 265–27