Summary of environmental impacts

FISH

Communities

The fish community has been studied at a number of outfalls in NSW. The two most sensitive species appear to be the eastern hula fish (Trachinops taeniatus) and rock cale (Crinodus lophodon). Decreases in the abundance of hula fish have been observed near Boulder Bay, Bellambi and Port Kembla outfalls (Smith et al 1998, TEL 1994). Decreases in the abundance of rock cale have been observed near Vaucluse and Warriewood outfalls, however, an increase (relative to reference locations) in the abundance of rock cale was recorded at Port Kembla outfall (Lincoln-Smith 1985, TEL 1994). No effect on fish communities were found at Penguin Head and Plantation Point outfall and only localised differences at Forster outfall.

A number of significant and sustained impacts on the demersal fish communities were attributed to the commissioning of the Malabar, North Head and Bondi deepwater outfalls (EPA 1996e).

Contaminant Loads

Contaminant loads in fish (and a number of invertebrate species) have been undertaken at many NSW outfalls. Sydney’s inshore sewage outfalls were significant contributors to organochlorine contamination of inshore sedentary fish such as red morwong (Cheilodactylus fuscus). Diversion of sewage to deepwater outfalls resulted in a marked decline in organochlorine compounds in these fish. Apart from lead, similar trends did not occur for concentrations of trace metals. There was no observed increase in the contamination of offshore fish species when the outfalls were diverted offshore (Krogh and Scanes 1996). This may be a result of improved source control, decreased usage of organochlorine pesticides and greater dilution of sewage effluent at the deep ocean outfall sites. A number of fish had relatively high levels in Newcastle waters in the late 1980s (Cole 1990). However, the majority of recent studies into contaminants in fish close to NSW outfalls have often failed to find any organochlorine contaminants or found these contaminants at levels well below National Food Authority (Anon 1992) guideline levels for the protection of human consumers of fish and other aquatic organisms. One of the major problems with contaminant in fish studies is the mobility of fish species and the potential for fish to move between ‘control’ and ‘impact’ locations. Other problems are associated with the reproductive status of fish where fat (and possibly contaminants) may be shifted from the body to the reproductive organs during breeding.

(Impac_5) Last updated May 2000