CSIRO releases 15 captive bred endemic spotted handfish into wild in Tasmania

Tuesday, May 6, 2025 

On Tuesday, April 29, Commonwealth Scientific and Industrial Research Organisation (CSIRO) researchers have released 15 juvenile captive bred spotted handfish originated at Seahorse World in Tasmania into the wild, at undisclosed location in River Derwent near Hobart. To help the critically endangered fish adapt to the new environment, the researchers provided them with "handfish hotels".

The researchers were planning to remove the "hotels" in approximately two weeks to encourage integration with the surrounding environment; until then, the researchers were planning to closely monitor the fish, with the unique spots being used to identify individuals. The breeding program, supported with funding by the Derwent Estuary Program, had started in 2017 and involved setting up two satellite populations: at Seahorse World and at the Melbourne Aquarium.

CSIRO research technician and project lead Carlie Devine said "Today is our first ever release of captive-bred juveniles, so we're very excited to put them in the water. ... It's been a long journey, first of all we had to work out how to get them to breed in captivity. ...It is still a very rare event for them to breed in captivity."

Senior biologist Rachelle Hawkins said that the 15 released fish are part of the 35 that hatched, with the remainder staying at the aquarium to continue boosting the captive population. Ms Hawkins said a hurdle to breeding was difficulty with identifying a handfish's sex, which was resolved in 2023 when the aquarium was able to use ultrasound to determine the sex.

Tasmanian artist Jane Bamford had been making the artificial spawning habitats that the handfish lays its eggs on in the captive breeding program. Jane has by now hand-crafted 7,500 ceramic poles.

Ms Devine said about the "handfish hotels": "We will have an intensive monitoring program ... we will check on the fish and do a hotel room service every couple of days to make sure they are all good and happy. The fish won't move much, so will be easy to find in the hotels, which they will keep for about two weeks. ... Once we remove the hotels, hopefully they will go on their merry way and integrate. We want to make sure they can survive in the wild. They are very hardy fish so we are positive that they will be fine. It's a long process and this is just one step in our captive breeding program."

The spotted handfish is an unusual fish, in that it has highly adapted pectoral fins, which appear like hands -- hence the name -- and allow it to walk on the seafloor. The species is classified as critically endangered on the IUCN Red List 2020 and has a restricted range, being found only in the estuary of Derwent River, Tasmania, and nearby areas. It was first listed as critically endangered in 1996, and became the first marine fish to join the list.

• Georgie Burgess. "Underwater 'hotels' in place to give spotted handfish a head start to life outside captivity" — ABC, April 29, 2025
• "Australia releases 15 endemic spotted handfish into wild for 1st time" — Yeni Şafak, April 29, 2025
• Brianne Tolj. "Aussies amazed by adorable video of extremely rare species: 'Very cute'" — Yahoo! News, March 29, 2025
• "Hands of hope hand fish exhibit" — Seahorse World, December 2, 2024
• Emily Brown. "How our scientists are working to save the Spotted Handfish" — CSIRO, October 11, 2024