Reproductive Biology of Estuarine Pufferfish, Marilyna pleurosticta and Tetractenos hamiltoni (Teleostei: Tetraodontidae) in Northern NSW: Implications for Biomonitoring

Abstract

Because of their broad distribution, site fidelity and long lifespan pufferfish (family Tetraodontidae) show potential as biomonitors of estuarine water quality, and as understanding the reproductive cycle is crucial to interpreting variations in contaminant loads in the tissues of biomonitors, we investigated the spawning season, length at maturity and body condition of two small sympatric pufferfish species (Marilyna pleurosticta and Tetractenos hamiltoni), in the Richmond Estuary, NSW. M. pleurosticta spawned in spring while T. hamiltoni spawned in winter. Female and male M. pleurosticta matured at a similar size (50% mature at 90 mm total length). In T. hamiltoni there was a more marked difference in size at 50% maturity, with males maturing at 80 mm and females at 110 mm TL. From the high values for hepatosomatic index (HSI) and its strong inverse relationship with gonadosomatic index (GSI) we inferred that lipid reserves in the liver play an important role in gonad maturation and spawning. Somatic condition factor (Kr) also varied, albeit less so, throughout the year, suggesting that body fat and muscle play lesser roles in providing energy for reproduction. Seasonality of liver lipid content and different spawning seasons have important implications for designing sampling strategies using these fish, especially when monitoring lipophilic contaminants.