Mangrove jack are an essential component of Queensland recreational and commercial fisheries, and one of the icon species for recreational fishers in tropical rivers and estuaries. Community stocking groups are keen to stock mangrove jack to create recreational fisheries in impoundments and to address perceived declines in natural riverine stocks. Despite this, knowledge of the biology of the species is incomplete and a genetic assessment of population structure has never been attempted. The efficacious management of natural populations of mangrove jack and the future development of effective stocking programs requires information on all aspects of their life cycle, instream habitat requirements, reproduction and maturation, mortality, recruitment into and emigration from river systems.
Managers of wild fish species accept that genetically distinct sub-populations of fish may possess novel genetic, physiological, behavioural and other characters that lead to distinct differences in life-history traits including growth rates, fecundity, disease resistance and abundance (Gold and Richardson, 1998). These differences theoretically contribute to the long-term adaptability, survival and resistance to human-induced or other environmental perturbations and can be jeopardised by inappropriate management. It would be imprudent to proceed with the expansion of stocking and aquaculture programs for this species without a comprehensive knowledge of the genetics of the populations. The genetic study will pre-empt potential conflict between management agencies and commercial and recreational interests. Information from the genetic analysis of the species will provide geographic detail for the sustainable use of the resource across State boundaries.