Comparisons of the Growth and Gonadal Development of Otolith-Stained, Cultured Black Bream, Acanthopagrus butcheri, in an Estuary with Those of Its Wild Stock

Abstract

Acanthopagrus butcheri was cultured from broodstock from a southwestern Australian estuary in which its abundance had declined. After marking their otoliths with alizarin complexone, the cultured juveniles were released into this estuary at 6 months of age. Regular sampling demonstrated that this stain persisted throughout the next 3.5 years and that, during the last two of those years, cultured fish dominated the black bream assemblage. Cultured fish grew slower than wild fish, with females reaching total lengths of about 182, 220, and 243 mm at 2, 3, and 4 years, respectively, compared with about 199, 248, and 286 mm in wild fish. However, cultured A. butcheri grew faster than wild A. butcheri in most other estuaries studied. By 3 years of age, essentially all wild fish, but only some restocked fish, had matured. Cultured females matured at a similar length but at an older age than wild females, and cultured males matured at both a greater length and older age than wild males. We conclude that cultured A. butcheri can be used to increase the abundance of a depleted stock, but the reason for the slightly reduced performance of cultured fish should be elucidated and overcome.

Keywords:

• sparid
• estuarine population
• cultured fish
• otolith stained
• wild stock
• biological performance

ACKNOWLEDGEMENTS

Gratitude is expressed to staff at the Aquaculture Development Unit, particularly Gavin Partridge, for his assistance with culturing black bream, and to many colleagues at Murdoch University, and especially Gavin Sarre, whose help with sampling was invaluable. We are indebted to Trevor Price for his advice and assistance in collecting broodstock. Barry Dawes, Andrew Kikeros, Bill Anderson, Paul Palmer contributed greatly to this project. Funding was provided by the Fisheries Research and Development Corporation, Challenger TAFE, and Murdoch University.