Facts about spotted black grouper
Spotted black grouper (Epinephelus daemelii) are known as black cod, saddled rockcod and saddletail grouper in Australia.
Spotted black grouper are true groupers belonging to the family Serranidae, subfamily Epinephelinae. Although commonly called ‘groper’ in New Zealand, the hapuku (Polyprion oxygeneios) and bass (P. americanus) are actually ‘wreckfishes’ belonging to the family Polyprionidae.
Range and habitat
Spotted black grouper are only found in southeast Australia (Spencer Gulf to southern Queensland, excluding Tasmania), Elizabeth and Middleton Reefs, Lord Howe and Norfolk Islands, and northern New Zealand.
In New Zealand the largest and possibly only breeding population is found in the Kermadec Islands Marine Reserve. Around mainland New Zealand spotted black grouper are relatively common on shallow reefs at Three Kings Islands and along Northland’s rocky east coast. Small juveniles have been recorded as far south as Hokitika on the west coast, and Palliser Bay in the east.
Spotted black grouper inhabit rocky reefs in estuaries and on the open coast to at least 50 m depth. They are replaced in deepwater by the hapuku, bass and the eightbar grouper (Epinephelus octofasciatus). They are highly territorial and may inhabit the same piece of reef for life. At the Kermadec Islands small juvenile spotted black grouper are found in large intertidal rock pools as well as amongst boulders at 20 to 30 m depth.
There is no population estimate for any spotted black grouper population. Spotted black grouper appear to have had very little fishing pressure anywhere in New Zealand, however those in eastern Australia are considered to be heavily depleted by line, set net and spear fishers. The spotted black grouper is classified as Near Threatened by the IUCN Red List of Threatened Species.
Diet and foraging
Spotted black grouper are opportunistic predators of smaller reef fishes and crustaceans (shrimps, crabs and rock lobster).
Very little is known about any aspect of the biology of spotted black grouper. They appear to be slow growing. In Australia estuarine habitats appear to be important nursery habitats for juveniles. Small fish are mostly females but they change sex to become males around 100 to110 cm in length. Social factors potentially controlling growth and sex change are unknown. Reproductive behaviour is unknown.