Importance of Release Habitat for Survival of Stocked Barramundi in Northern Australia
D.J. Russell and M. A. Rimmer
Barramundi Lates calcarifer is a large, euryhaline, catadromous centropomid found throughout much of the Indo-West Pacific, including northern Australia where it is highly sought after as a sport, recreational, and commercial species. It also supports a growing aquaculture industry, and it was the successful development of technology for the large-scale production of this species that prompted interest in stock enhancement. There is evidence that the recreational and commercial fisheries are in decline (Rimmer and Russell 1998), and stock enhancement is perceived as one of a number of management tools that could be used to address this issue. Stock enhancement programs in Queensland coastal rivers have been under way since the early 1990s. Additionally, new put-and-take recreational fisheries for barramundi have been created in freshwater impoundments using hatchery-reared barramundi.
Since 1992, the Queensland Department of Primary Industries (DPI) has released more than 120,000 hatchery-reared juvenile barramundi as small as 30 mm total length (TL) into the Johnstone River in northeastern Australia, as part of an experimental stock-enhancement program. Stocked fish take between three to four years before they are recruited into the fishery but now make up about 19% and 13% of the recreational and commercial catches, respectively (Russell and Rimmer 1997; Rimmer and Russell 1998). The study also provided useful information on barramundi movements. Most (62%) stocked fish, particularly juveniles, were recaptured within 3 km of their release location, and 37% made intra-riverine movements of between 3 and 37 km. Five fish made inter-riverine or coastal movements (Russell and Rimmer 1997; Rimmer and Russell 1998).