Giant Groper's age established: NSW DPI

The giant 2.2 metre long Queensland Groper, found dead in the Clarence River last November was 37 years old, according to the NSW Department of Primary Industries.

"An analysis of growth rings in the ear bone of the giant fish has put its age at 37 years," said Bruce Pease, NSW DPI scientific officer based at Port Stephens.

"The groper was actually fairly small for its age, probably due to the fact it spent most of its life in cooler southern waters."

NSW DPI submitted small bones in the groper’s inner ear, called otoliths, to James Cook University for analysis after it was found dead in the Clarence River on 21 November last year. The cause of death of the fish is unknown. 

"The otolith grows less in winter and more in summer resulting in the appearance of rings that resemble tree rings," said Dr Pease.

"By counting the rings on the otolith, it is possible to determine the age of the fish in years."

Queensland groper (Epinephelus lanceolatus) are one of the largest species of fish in Australian waters, and can grow up to 3 metres long and weigh 600kg.

The Clarence fish was the oldest Queensland groper that James Cook University scientists had aged - but it was small relative to its age. A 10-year-old Queensland groper examined the previous week measured 1.8 metres.

Dr Pease said he was unsure whether this fish was a long-term resident of the Clarence River or whether it lived in marine waters and seasonally entered North Coast estuaries such as the Clarence.

"This is not the first time a Queensland groper has been found in the Clarence," he said.

"In the early 1900’s, large Queensland groper were occasionally caught in the lower Clarence River by commercial fishers.

"The slower growth of the Clarence fish may have resulted from the fact it was living in cooler waters near the southern end of the geographic range for this species.

"This widely distributed species of fish is found throughout the Pacific and Indian Oceans and occurs along all tropical and warm temperate coasts of Australia, but they are not abundant in NSW waters.

"Queensland groper are solitary in nature and rely on ambush techniques to hunt for a variety of marine species ranging from fish, small turtles and sharks as well as many crustaceans including crabs."

Queensland Groper are protected in NSW under the Fisheries Management Act 1994 and heavy penalties can apply if anyone is caught taking or possessing this species.

Information on the species can be obtained from the NSW DPI website www.dpi.nsw.gov.au/fisheries/threatened-species/giant-queensland-groper