The life and times of rock flathead under investigation	FN 0529
Matt Koopman, Marine and Freshwater Resources Institute August, 2002

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Little information exists on the life history of rock flathead. This is despite this species being a mainstay of the commercial fishery in Corner Inlet. The annual catch in Corner Inlet in recent years has averaged about 30 t, and is worth approximately $75,000. MAFRI’s fisheries scientists are undertaking a two-year research project aimed at collecting some basic biological data on this species.

Matt Koopman, with the help of local fishers, has obtained approximately 1200 rock flathead from Corner Inlet between February 2001 and January 2002. These fish were measured, aged, sexed and their reproductive organs taken for analysis. His work has revealed that on average female rock flathead appear to grow faster and attain a greater size than males. At 5 years old female rock flathead have reached 39 cm on average, whereas males are only 34 cm. At 10 years old females are on average 48 cm and males only 40 cm. The oldest rock flathead found in Corner Inlet was 19 years old. This was a female fish with a length of 55 cm. The largest fish caught from Corner Inlet measured 57 cm in length, and previously the species was thought to reach only 50 cm.

MAFRI scientists have also found that the growth of rock flathead is highly variable meaning that big fish are not necessary old fish. For example the study revealed that a 4 year old male fish could be anything between 28 and 39 cm long and a female fish, measuring 40 cm could be 4 years old or it could be 10 years old.
The advice provided in this publication is intended as a source of information only. The State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication.

Rock flathead spawn from September through to February with the maximum spawning effort occurring in October. The reproductive data obtained by MAFRI scientists suggests that rock flathead aggregate according to sex, with some of the catches being heavily dominated by males, and others by females. Similar patterns of aggregation have been observed in sand flathead from Port Phillip Bay and tiger flathead in offshore waters.

These data will be used to develop a stock assessment model for this commercially important species in Corner Inlet. The stock assessment model will provide information to fishers and Fisheries Victoria which will be crucial for the management of a sustainable rock flathead fishery.

The project is funded by Fisheries Victoria and the Fisheries Research and Development Corporation.

For more information about rock flathead research, contact Matt Koopman at MAFRI on 52580342.

The advice provided in this publication is intended as a source of information only. Always read the label before using any of the products mentioned. The State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication.

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