Catch characteristics of the commercial beach-seine fisheries in two Australian barrier estuaries

Abstract

A scientific observer programme was used to estimate the retained and discarded catches taken in two of the largest commercial beach-seine fisheries (Lake Macquarie and St. Georges Basin) in New South Wales, Australia. Catches were sampled in each estuary in each of four seasons throughout 1998/1999 and the data were used to estimate the quantities and length compositions of species caught, retained and discarded in these fisheries and to assess potential interactions with other fisheries. A total of 118 catches were sampled which yielded 72 finfish and 10 invertebrate species. Multivariate analyses showed that the mix of species in catches varied between estuaries, with 70 species (41 of which were retained) captured in Lake Macquarie and 37 species (26 retained) in St. Georges Basin. Despite these differences, the predominant species taken and patterns of discarding were similar in the two fisheries. The sparids Rhabdosargus sarba, Acanthopagrus australis and the gerreid Gerres subfasciatus were three of the four most abundant species caught in each estuary, with 99, 88 and 34% of these species discarded, respectively. Compliance with minimum legal length (MLL) accounted for most discarding practices, but for those species with no MLL, discarding was generally market-driven and size-based. An estimated 65% by number and 57% by weight of the catch in Lake Macquarie, and 77% by number and 59% by weight of the catch in St. Georges Basin, was discarded. We estimated that a total of 468 t (269 t discarded) was caught in Lake Macquarie and 143 t (85 t discarded) was caught in St. Georges Basin throughout the 1 year survey. We discuss our findings in relation to interactions with other fisheries and future management strategies.