DISTRIBUTION, BIOMASS AND COMMUNITY STRUCTURE OF DEMERSAL FISHES OF THE GULF OF CARPENTARIA, AUSTRALIA

The demersal fish fauna of the Gulf of Carpentaria was surveyed during November and December 1990. Over 300 species from 85 families were ca ught by trawling a systematic grid of 107 stations. The absolute mean biomass was 124.8 kg ha-1 (s.e. = 44.1) for day trawls and 53.7 kg ha- 1 (s.e. = 6.0) for night trawls. The overall mean catch rates were 421 .3 kg h-1 (s.e. = 128.5) for day trawls and 198.6 kg h-1 (s.e. = 21.5) for night trawls. Biomasses were twice as high in the prawn-trawling grounds of Albatross Bay, the south-eastern gulf and Groote Eylandt as they were elsewhere in the gulf. Twenty-five species made up 75% of t he biomass; the dominant families were Haemulidae, Carangidae, Leiogna thidae and Nemipteridae. Community-structure and distribution patterns were analysed by numerical classification techniques and principal-co ordinates analysis. These indicated six main site groups and 15 fish c ommunity groups, based on fish species occurrences and biomasses. Ther e was a relationship between fish distribution patterns and depth of w ater but not other abiotic factors recorded (sediment type, salinity, temperature and turbidity).