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Reprinted from CSIRO's science and environment magazine, ECOS.

There's an unusual little pear-shaped fish that was once common in the Derwent Estuary in Tasmania that may have the dubious honour of being the first species of marine fish to become extinct! It's called the spotted handfish (Brachionichthys hirsutus) and its population, which is known to occur only in the Derwent Estuary, has collapsed over the past decade. It's now listed as endangered and Barry Bruce, a fish biologist from CSIRO's Division of Fisheries, says it's on the way to becoming the first known species of marine fish to have died in recorded human history.

The Spotted Handfish, Brachionichthys hirsutus

Named after its strange hand-like fins, the spotted handfish grows to about 10cm, is cream in colour with yellow and black spots, and lives by walking along the bottom of the Derwent Estuary.

The spotted handfish was one of the earliest Australian marine fish collected (in the late 1790s) and was first described in 1804. It grows to 150 millimetres in length and is noted for its superb colouring and its tendency to 'walk' over the sea floor on leg-like fins.

Until the mid 1980s, the handfish was common throughout the lower Derwent Estuary and adjoining bays and channels, but has since declined in distribution and abundance. It was protected under State Fisheries Legislation in 1995, and was listed under the Federal Endangered Species Act in 1996.

Alarmingly, there have only been four confirmed records of it in the past five years!

Concerns over dwindling numbers prompted the formation of a 'handfish recovery team', with representatives from CSIRO, the Tasmanian departments of Primary Industry and Fisheries and Environment and Land Management, the University of Tasmania, Environment Australia, the Hobart Ports Corporation and the Tasmanian Conservation Trust.

Jon Bryan, a marine biologist working with the Tasmanian Conservation Trust, believes the handfish may have been the victim of the recent introduction of the north Pacific seastar. Thought to have arrived in the ballast water of trade ships in the mid-1980s, the seastar has eaten out many local shellfish populations. Handfish lay their eggs in a nest on the sea floor and it's believed that the voracious seastars have being making a meal of them as well.

Research on the spotted handfish began with funding from Environment Australia in early 1996. So far it has involved surveys to locate remnants of former handfish populations in the Derwent Estuary, and monitoring of these colonies to study its biology and habitat. Captive husbandry techniques have also been developed in collaboration with the Tasmanian Department of Primary Industries and Fisheries at Taroona.

The goals of the captive breeding program have been to gather further information on the reproductive biology of spotted handfish, as well as to provide an insurance policy should the species continue to decline in the wild, or should reintroduction be required.

Bruce says the handfish has turned out to be an ideal species to work with. They are small, slow moving, and recognisable individually by their unique spotted patterns. This enables easy monitoring of individual growth rates, movement patterns and estimates of population size and age structure.

It is now known that spotted handfish have a low breeding capacity, the female laying only 80-250 very large eggs which are held together by threads and generally attached to the seafloor. The female guards the egg mass which takes six to seven weeks to hatch and is highly susceptible to disturbance.

Despite these difficulties, Bruce and his colleague Mark Green have produced for the first time the right conditions for spawning and rearing of juveniles in artificial tanks. They have bred 35 juveniles from two adult pairs at the Tasmanian Department of Primary Industry and Fisheries Aquaculture facilities at Taroona.

'Although there are still many gaps in our understanding of the spotted handfish and what affects them, the information we have gathered to date has now been used to develop a recovery plan for them,' Bruce says.

"We believe we now have the techniques to proceed with developing a larger-scale breeding program for this and other related handfish species if required," said Barry Bruce, a biologist at CSIRO's Division of Marine Research in Hobart. "The next step is to develop a plan to guarantee the recovery of this species," he said. Mr Bruce, who leads the Environment Australia (Commonwealth Endangered Species Program) and CSIRO-funded research project, said the breeding results are an especially significant milestone in the International Year of the Ocean.

The plan includes the following strategies:

• establish the biological characteristics affecting the dynamics of handfish colonies and their response to changes in the environment;
• establish a way of assessing population size and stability;
• investigate causes of the species' decline;
• develop a population response model to assess timeframes and the progress of recovery and the implications of population size, and to identify and reduce major uncertainties in the recovery process; and
• take immediate steps to enhance spawning areas, further develop captive breeding techniques and trial reintroductions.

'We hope that with the collaboration of all the groups involved, the handfish will be around for a long time to come,' Bruce says.