Black Bream Spawning - Supply of Juveniles

Black bream usually migrate upstream into the middle reaches of estuaries to spawn in the mid-spring and early summer (Sarre & Potter, 1999). Spawning has also been reported within closed lakes in both western and eastern Australia (Rowland 1984).

Spawning Times

Spawning time may vary between geographically isolated water bodies. This has been attributed to variations in environmental cues such as dissolved oxygen and salinity (Tregonning et al. submitted) and probably temperature, in common with other sparids (Haddy & Pankhurst 1998). They spawn in the narrow upper reaches of the Swan River estuary (WA) from September to December (Sarre & Potter, 1999) and in two Tasmanian rivers there was a three-month spawning season in spring-early summer (Haddy and Pankhurst, 1998). The salinity encountered in spawning areas in estuaries may vary from 11-18 ppt (Rowland, 1984), 3.6-45.2 ppt (Sarre and Potter, 1999) and 14-35 ppt (Haddy and Pankhurst, 1998), however, black bream mature and spawn in seawater (35 ppt) at the FMC (Jenkins et al., 1999).

Husbandry

Black bream are hermaphroditic, so individuals possess both female and male gonadal tissue. This structure, characteristic of the Sparid family, is called an ovotestis. There is circumstantial evidence that the type of hermaphroditism found in black bream, at least in the case of populations in WA, is rudimentary and that sex change does not occur (Sarre, 1999). Black bream can mature after 2-4 years of age at total lengths ranging from 130 - 218 cm, depending on the particular estuary (Sarre & Potter, 1999). In captivity, early maturation of many species of fish occurs. The excellent husbandry procedures at the FMC have made hormonal injections unnecessary for spawning induction although manual stripping of eggs can also be used if necessary (Jenkins et al., 1999). The natural changes in reproductive hormones in wild black bream have been described by Haddy & Pankhurst (1998).

Female black bream are multiple spawners which means they spawn more than once during each breeding season. Estimates of total fecundity range between 90,000 and seven million eggs per season depending on the size of the fish (Sarre & Potter, 1999). Overall, egg supply is not a limiting factor for aquaculture of this species.

Hatching and Larvae

Eggs hatch in about 20 hours at 26 o C and the larvae are fed zooplankton from Day 3. The larvae are relatively easy to rear using green water (in the presence of algae) or clear water techniques (see Partridge et al., 1998 and Jenkins et al., 1999 for well explained, detailed methodology). The larvae can be weaned onto formulated feeds after 3-5 weeks. Juveniles can be grown on to a suitable stocking size and transported to ponds or cages in sealed bags containing seawater and oxygen.

Those interested in black bream in general and fingerling production in particular should consult the following Fremantle Maritime Centre publication.

Jenkins, G.I. Frankish, K.R. & Partridge G.J. 1999. Manual for the diet Production of Black Bream (Acanthopagrus butcheri) . Aquaculture Development Unit, Information Series 1991/1, 125pp.

It can be bought from

Fremantle Maritime Centre
1 Fleet St
Fremantle WA 6160
Australia

or is available from the Department of Fisheries Library .

Fremantle Maritime Centre periodically runs training courses on black bream aquaculture.

Contact Greg Jenkins
Ph: (08) 9239 8030
or e-mail: JenkiG@FLEETST.training.wa.gov.au

Informtation courtesy of the WA Department of Fisheries