Rationale, results and management implications of recent carp research in Australia.

Carp are the most prominent pest freshwater fish species in Australia, being relatively large, visible in high numbers and caught by anglers. They have spread rapidly since the 1960s, occur throughout most of southeastern Australia and now dominate many fish populations there, in addition to populations in Western Australia. There is now considerable public pressure for carp control. In response to this there have been several new research initiatives which provide information for management actions. This work includes some information on impacts; mainly confined to wetlands rather than rivers, and involving turbidities and waterplants. More definitive biological information has been obtained on movements, spawning areas and conditions, ageing, and population structure. Carp densities have been correlated with the degree of river regulation and research has been conducted on control options which include: daughterless carp technology, commercial harvest, manipulation of water levels and exclusion. A brief review of these new findings is presented in this paper together with management implications, the future of carp in Australia, and lessons which may be learnt for management of carp in New Zealand. 1 . B A C K G R O U N D Although there are 36 species of introduced fish now recorded or established in Australian inland fresh waters (Arthrington et al. 1999), carp are the largest, most visible and cause the most public concern. Despite not being recognisable by external features, there are four strains of carp in Australia: Koi (mainly in Australian Capital Territory, Tasmanian and Western Australia), Prospect (Sydney), Yanco (Murrumbidgee Irrigation Area) and Boolara. Although carp were first introduced into Australia mid last century, carp populations remained relatively contained until the introduction of the ‘Boolara’ strain to Gippsland in Victoria in the 1960s. Once this strain was introduced it spread rapidly. Carp are now widely distributed throughout southeastern Australia with smaller populations in Western Australia and Tasmania (Fig. 1). Carp now dominate fish