Brown-marbled grouper  (Epinephelus fuscoguttatus)

Classified as Near Threatened (NT) on the IUCN Red List 2006 (1).

The brown-marbled grouper is a robust marine fish, with a pale yellowish-brown, scaled body, covered with large, irregular, dark brown blotches. The head, back and sides are also covered with close-set tiny brown spots. The head profile is slightly indented at the eye, and then curves out towards the start of the dorsal fin. The tail, or caudal, fin is rounded (3).

The brown-marbled grouper occurs throughout the Indo-Pacific region; from the Red Sea to the Samoan Islands, north to the Ryuku Islands and south to the Great Barrier Reef (3) (4).

The brown-marbled grouper inhabits shallow water over coral reefs and rocky bottoms, in areas of rich coral growth and clear water, down to depths of 60 meters. Juveniles are found in areas of seagrass (3) (4).

This long-lived fish has a fascinating and complex life-history. It is a protogynous hermaphrodite, meaning that individuals first function sexually as females and then later, at least some of the mature females change to males. It is thought that this sex change can occur at a wide range of sizes and ages, although not all individuals change sex. A brown-marbled grouper can live for over 40 years, an incredibly long time for a fish, and can reproduce for over 30 of those years, during which time they form large aggregations to spawn (2).

The brown-marbled grouper is one of the largest fish predators on coral reefs (5), and is mainly active at dusk, when it feeds on fishes, crabs and cephalopods (3) (6). This secretive and wary fish may be ciguatoxic (5); that is, the flesh may be contaminated with a toxin that can make humans very sick if consumed.

The brown-marbled grouper is an important component of regional fisheries, and several biological characteristics of this species result in it being particularly vulnerable to over-fishing. As it forms spawning aggregations it is an easy and attractive target for fishermen; the long lifespan means that the population can take many years to recover if numbers become depleted; and as a protogynous hermaphrodite, it is greatly threatened by the trend of fishermen to target larger fish. The large individuals of a population includes all the males that are vital to maintain the sex ratio, as well as important female breeders that are highly fertile and contribute a substantial proportion of young to the population for many years (2). Removing all the large individuals from the population can have devastating consequences. The destruction of seagrass beds and coral reefs due to human activities also poses a threat to the survival of this species (1).

In many parts of the brown-marbled grouper’s range there are conservation measures in place. For example in Queensland, Australia, there are minimum and maximum size limits for catches; in Papua New Guinea, night time spear fishing at a known spawning aggregation site is prohibited; and in Palau, the Marie Protection Act of 1994 prohibits sale or purchase of this species from April 1 to July 31 each year (1). This species also occurs within a number of marine protected areas, such as the Great Barrier Reef Marine Park (5). However, these laws are not always adhered to (1), and it has been suggested that the current maximum size limit in Queensland is too high to protect a sufficient number of breeding individuals (2).

View information on this species at the UNEP World Conservation Monitoring Centre.

For further information on the brown-marbled grouper see Pogonoski, J.J., Pollard, D.A. and Paxton, J.R. (2002) Conservation Overview and Action Plan for Australian Threatened and Potentially Threatened Marine and Estuarine Fishes. Environment Australia, Canberra, Australia. Available at:
http://www.environment.gov.au/coasts/publications/marine-fish-action/pubs/marine-fish.pdf

For further information on the conservation of Australian marine fishes see the Australian Marine Conservation Society:
http://www.amcs.org.au/