A Comparison of Fish Assemblages and Fisheries in Intermittently Open and Permanently Open Coastal Lagoons on the South Coast of New South Wales, South-Eastern Australia

The fish assemblages inhabiting two intermittently open coastal lagoons and one permanently open coastal lagoon on the mid south coast of New South Wales were studied over several years during the mid to late 1980s. Fish were sampled either monthly or bimonthly using rotenone ichthyocide 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 within lagoons and between the two lagoon types using a multivariate ordination technique. In the permanently open lagoon, Lake Conjola, dominant faunal elements of commercial or recreational fisheries importance included Girellidae, Clupeidae, Monacanthidae, Pomatomidae, Mugilidae, Sparidae, Sillaginidae, Gerreidae, Terapontidae, and Platycephalidae. Dominant faunal elements of no commercial or recreational fisheries importance here included Ambassidae, Scorpaenidae, Gobiidae, Atherinidae, and Eleotridae. In the intermittently open lagoons, Swan Lake and Lake Wollumboola, the dominant faunal elements included Sparidae, Mugilidae, 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 (∼100 species, including 52 commercial species) was found to be approximately 2.5 times that of each of the two intermittently open lagoons (39 species, including 22 commercial species for Swan Lake; and 41 species, including 26 commercial species for Lake Wollumboola). The dominant faunal elements of the latter two south-eastern Australian intermittently open lagoons were also compared with those of similar lagoons in south-western Australia, southern Africa, and western Mexico, and the faunal similarities at the species, genus, and family levels are discussed. Available commercial and recreational fisheries catch data for the three south-eastern Australian coastal lagoons were also analyzed and compared. The two intermittently open lagoons were found to support larger fisheries (in terms of both catch weight and value) than the permanently open lagoon, in spite of the larger number of species in the latter and also its greater water surface area.