West Australian Dhufish
Scientific name: Glaucosoma hebraicum
Phylum: Chordata
Distribution:
Dhufish are endemic to Western Australian and are found from Shark Bay to the Recherche Archipelago near Esperance.
Description:
Dhufish can live for more than 40 years, reach more than a metre in length and weigh more than 25 kilos. As with many bottom-dwelling fish they are relatively slow-growers. Dhufish reach sexual maturity at three to four years old, or when they are 30 – 35 cm long.
Adult dhufish have a distinctive vertical dark line called a chevron running through their eye that fades once they die and which is also fainter on females. Juvenile Dhufish have six black stripes along their body.
Ecology:
Dhufish prefer to live around rock outcrops and ledges. They can usually be found in water 20 to 50 metres deep, however sometimes they may be present in water as shallow as 3 metres.
Dhufish have big eyes are cavernous mouth, which they prey on other fish, crustaceans and molluscs such as squid and octopus. As larvae and juveniles they may be prey to a wide range of other sea creatures.
During spawning, eggs and sperm are released into the water and fertilisation occurs externally. At these times, dhufish gather in small groups called aggregations. This generally occurs between November and April with the peak period being between December and March, when water temperatures are highest.
While there is much about dhufish behaviour that is yet to be fully understood, it appears that this species displays complex social behaviour during spawning with larger individuals dominating and achieving greater spawning success.
Interesting facts:
Tagging studies have shown that they are generally sedentary – that is, they usually do not travel far from home. Adult male dhufish are often bigger than female dhufish. Any easy way to tell the difference between male and female dhufish is the elongated filament on the dorsal fin on males. In the past, dhufish have also been called jewfish or ‘jewies’.
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 catch of dhufish.
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. A recent study has estimated that 86% of released dhufish died after being caught in waters deeper than 45 metres.
To download the complete Fact Sheet from the Department of Fisheries WA website click here:
http://www.fish.wa.gov.au/docs/pub/FactSheets/dhufish-download.php |
