A COMPARISON OF FISH ASSEMBLAGES AND FISHERIES IN INTERMITTENTLY OPENAND PERMANENTLY OPEN COASTAL LAGOONS ON THE SOUTH COAST OF NEW-SOUTH-WALES, SOUTH-EASTERN AUSTRALIA

The fish assemblages inhabiting two intermittently open coastal lagoon s and one permanently open coastal lagoon on the mid south coast of Ne w South Wales were studied over several years during the mid to late 1 980s. Fish were sampled either monthly or bimonthly using rotenone ich thyocide and beam trawls (in shallow vegetated habitats), beach:seines (in shallow inshore sand habitats), and multiple-panel gill nets (in deep lagoon habitats with mud or sand floors). These fish assemblages were compared and contrasted spatially according to habitat both withi n lagoons and between the two lagoon types using a multivariate ordina tion technique. In the permanently open lagoon, Lake Conjola, dominant faunal elements of commercial or recreational fisheries importance in cluded Girellidae, Clupeidae, Monacanthidae, Pomatomidae, Mugilidae, S paridae, Sillaginidae, Gerreidae, Terapontidae, and Platycephalidae. D ominant faunal elements of no commercial or recreational fisheries imp ortance here included Ambassidae, Scorpaenidae, Gobiidae, Atherinidae, and Eleotridae. In the intermittently open lagoons, Swan Lake and Lak e Wollumboola, the dominant faunal elements included Sparidae, Mugilid ae, Girellidae, Hemiramphidae, Pomatomidae, and Arripidae amongst the commercial group; and Atherinidae, Syngnathidae, Gobiidae, Eleotridae, and Scorpaenidae amongst the noncommercial group. The overall species richness of the permanently open lagoon (approximately 100 species, i ncluding 52 commercial species) was found to be approximately 2.5 time s that of each of the two intermittently open lagoons (39 species, inc luding 22 commercial species for Swan Lake; and 41 species, including 26 commercial species for Lake Wollumboola). The dominant faunal eleme nts of the latter two south-eastern Australian intermittently open lag oons were also compared with those of similar lagoons in south-western Australia, southern Africa, and western Mexico, and the faunal simila rities at the species, genus, and family levels are discussed. Availab le commercial and recreational fisheries catch data for the three sout h-eastern Australian coastal lagoons were also analyzed and compared. The two intermittently open lagoons were found to support larger fishe ries (in terms of both catch weight and value) than the permanently op en lagoon, in spite of the larger number of species in the latter and also its greater water surface area.