OBSERVER-BASED SURVEY OF BY-CATCH FROM PRAWN TRAWLING IN BOTANY BAY AND PORT JACKSON, NEW-SOUTH-WALES

Catches and by-catches were surveyed in the commercial prawn trawl fle ets of Botany Bay and Port Jackson, two estuaries in the Sydney metrop olitan area (NSW, Australia). Catches were surveyed in all tows during replicate fishing trips in each month during the 1990-91 and 1991-92 prawn trawl seasons in each estuary. Significant species-specific vari abilities in abundances were detected between estuaries, between years , and between early and late in the fishing season. The mean annual ra tio of by-catch to catch of prawns (by weight) was 2.5:1 for Botany Ba y and 1.8:1 for Port Jackson. A mean annual by-catch (+/- 1 s.e.) of 1 42 +/- 14 t was taken from the Botany Bay fishery and 38 +/- 3 t from Port Jackson. These by-catches included large numbers of small recreat ionally and commercially important finfish: a mean annual by-catch of 1.52 +/- 0.20 million fish from Botany Bay and 219 +/- 23 thousand fis h from Port Jackson. Despite uncertainties about the impacts of such b y-catches on interacting commercial and recreational fisheries, it is recommended that strategies for the reduction of such by-catches be co nsidered.