Australian Bass - Conservation

Conservation

Wild Australian bass stocks have declined seriously since European settlement.

Dams and weirs blocking migration of Australian bass both to estuaries and to the upper freshwater reaches of coastal rivers is the most potent cause of decline. Most coastal rivers now have dams and weirs on them. If Australian bass are prevented from migrating to estuaries for breeding by an impassable dam or weir, then they will die out above that dam or weir. Some dams or weirs exclude Australian bass from the vast majority of their habitat. It is estimated for example that Tallowa Dam on the Shoalhaven River, once an Australian bass stronghold, currently excludes wild Australian bass from more than 80% of their former habitat (in early 2010 however a "fish lift" was fitted to the dam). Dams and weirs also diminish or completely remove flood events required for effective breeding of adult bass and effective recruitment of juvenile Australian bass. A related issue is the myriad of other structures on coastal rivers such as poorly designed road crossings that (often needlessly) block migration of Australian bass.

Another potent cause of decline is habitat degradation. Unfortunately poor land management practices have been the norm historically in Australia. Complete clearing of riparian (river bank) vegetation, stock trampling river banks, and massive siltation from these poor practices as well as poor practices in the catchment, can severely degrade and silt coastal rivers to the point of being uninhabitable for Australian bass. The Bega River in southern New South Wales is a particularly salutory example of a coastal river so stripped of riparian vegetation and so silted with coarse granitic sands from poor land management practices, that the majority of it is now completely uninhabitable by Australian bass and other native fish.

As a slow-growing fish, Australian bass are vulnerable to overfishing, and overfishing has been a driver of decline in Australian bass stocks in past decades. However, the situation has improved markedly now the majority of fishermen are practicing catch and release with Australian bass.

Hatchery breeding and stocking of Australian bass is used to create fisheries above dams and weirs but these are causing concern over genetic diversity issues, use of bass broodfish from different genetic strains, and introduction/translocation of unwanted pest fish species in stockings. Stockings can also mask and divert attention away from serious habitat degradation and decline of wild stocks in catchments.