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Distribution and Habitat Preferences of the Endangered Oxleyan Pygmy Perch Nannoperca oxleyana in North-Eastern New South Wales

James Knight

NSW Fisheries, NELSON BAY, AUSTRALIA

THEME: ASFB

Research into the distribution and habitat preferences of the endangered Oxleyan pygmy perch Nannoperca oxleyana (Fam. Percichthyidae) in north-eastern New South Wales was commenced during 2000. Sampling involved intensive surveys of heathlands near Evans Head followed by extensive surveys to determine the species' limits of distribution within New South Wales. Nannoperca oxleyana was only recorded from a total of 32 waterbodies along approximately 100 kilometres of sandy coastal lowlands situated between Ballina and Coffs Harbour. Within this area, the species typically inhabited coastal wallum creeks and lakes characterised by tannin-stained, acidic (pH ~ 3 - 5) freshwaters (90 - 320µS. cm-1), where it frequented low flow environments (< 0.3m. sec-1) in moderate water depths (<1.3m). Multilevel Poisson regression analysis revealed that higher abundances of N. oxleyana were caught near steep/undercut banks than amongst aquatic vegetation, and also within these two microhabitats than in open water. Catches of this species also increased as habitats became shallower, contained more leaf litter, snags, steep/undercut banks and aquatic vegetation, and substrates comprised more sand. Nannoperca oxleyana was not recorded from 55 waterbodies with apparently suitable habitat for supporting the species, although one third of these sites were degraded by urban and rural development and/or sand mining operations. This study has provided important baseline data, which is currently being used NSW Fisheries to develop a recovery plan for the species.