Baldchin Groper
Scientific name: Choerodon rubescens
Phylum: Chordata
Distribution:
Baldchin Groper are endemic to Western Australian and are found between Coral Bay and Dunsborough.
Description:
Baldchin groper are members of the Labridae or wrasse family. With protruding tusk-like teeth in both jaws, they are one of the largest species of tuskfish, reaching about 70 centimetres in length and seven kilos in weight. Baldchin may live to at least 22 years old. Like many other bottom-dwelling fish, they are slow growing. They take around five to seven years to reach 40 centimetres in length.
Baldchin can be identified by their white chin, which is especially obvious in older males – giving this species its common name. Their body colour is quite variable, ranging from yellowish-brown for juveniles to pinkish-grey and even greenish-blue for large males.
Ecology:
Baldchin live on the continental shelf, on shallow and deep reefs or over seagrass. They are carnivorous and feed on squid, octopus, sea urchins and occasionally crustaceans. Juvenile baldchin are sometimes found in shallow sandy areas near coral reefs.
While usually solitary or inclined to reside in small groups, baldchin aggregate (gather in groups) to spawn. During this time, they have been observed aggregating in large numbers of up to a hundred fish.
At the Abrolhos Islands, spawning usually occurs from early spring to mid-summer with the peak period being November to early January. It is thought that female baldchin are serial spawners, releasing eggs in a series of batches over one breeding season.
Interesting facts:
It may sound strange to us but, as with most wrasses, baldchin groper begin adult life as females and later turn into males. The scientific terms for this is ‘protogynous hermaphrodite’. They are most abundant at the Houtman Abrolhos Islands, 60 kilometres west of Geraldton, which is also their main know spawning ground. They are powerful swimmers and are quite capable of breaking a fishing line as they dive for cover among rocks and coral.
Status:
Due to overfishing by commercial and recreational fishers, the Department of Fisheries in Western Australia has implemented new management arrangements to achieve a 50% reduction in the catch of baldchin groper.
The fish’s peculiar life cycle poses particular challenges for fisheries managers. Researchers have suggested that if only large male baldchin are removed from the population there may be a shortage of males for reproduction.
Like other bottom-dwelling fish, they suffer from batotrauma, when caught in deep water and pulled rapidly to the surface on a fishing line. Barotrauma is condition that results from gases expanding in the fish’s body, and exhibits symptoms such as a bloated stomach, bulging eyes and the stomach pushed out through the mouth or gills. The mortality or death rate of undersize and unwanted baldchin groper that are returned to the water after capture is thought to be very high, even if captured in relatively shallow water.
To download the complete Fact Sheet from the Department of Fisheries WA website click here:
http://www.fish.wa.gov.au/docs/pub/FactSheets/baldchin-groper-download.php |
