Biological performance and genetics of restocked and wild bream in an Australian estuary

This study describes the results of a long‐term investigation into the biological performance and genetics of restocked and wild black bream (Acanthopagrus butcheri) in the Blackwood River Estuary in south‐western Australia. The restocking was done in 2002‐03 and involved the release of juveniles of black bream, cultured using broodstock from the Blackwood River Estuary, in an attempt to replenish a heavily depleted population of this species in this system. The results of an investigation into the biological performance of the restocked fish for 3.5 years after their release into the estuary have already been published. This study builds upon this early work by providing information about the growth rates of restocked and equivalent wild individuals for eight years post‐release, the proportion of restocked individuals reaching maturity, and the contribution of the restocked individuals to the gill‐net fishery for this species in the estuary. It also includes the first information on the genetic consequences and implications of this restocking. The results demonstrate that the restocking of the black bream in the Blackwood River Estuary has been very successful in most respects and highlight the value of long‐term monitoring in fish restocking programs