Rare red handfish returned to Tasmanian wild after riding out marine heatwave in tank

The red handfish’s tiny population distribution makes it vulnerable. (Supplied: IMAS )

Nearly a fifth of the critically endangered red handfish population has been released back into its natural environment, following a successful rescue program over the summer.

Twenty-five red handfish were removed from Frederik Henry Bay in south-east Tasmania in January after scientists raised the alarm that a marine heatwave could wipe out the unique animal.

The fish’s alarmingly low population — it’s estimated there are about 100 red handfish left — and unprecedented ocean temperatures prompted the Institute of Marine and Antarctic Studies to act.

Of the 25 fish removed in January, 18 were returned in early April, while four have been kept in captivity as an insurance population.

Three of the rescued red handfish have died.

The marine ecologist overseeing the rescue program, Dr Jemina Stuart-Smith, said it was a relief to have the fish back into their natural environment.

“It might seem like a really simple exercise — the actual work itself wasn’t complicated, removing and returning fish,” Dr Stuart-Smith said.

“But there’s a lot of pressure on us when you think about the size of the population and, and the risk of action and inaction.”

Novel conservation approach may become more common

The urgent intervention was green lit by the Australian government last December as degraded habitat in Frederik Henry Bay from over grazing by native urchins and a prolonged heatwave signalled an existential risk to the fish.

A “national interest exemption” under environmental law was provided by Environment Minister Tanya Plibersek to allow scientists to remove the fish from the bay.

The Albanese government has pledged there will be no new extinctions.

The red handfish is a small anglerfish which uses its under-developed fins to “walk” along the ocean floor, however its limited environment — its only known habitat is two small stretches of reef — and tiny population distribution makes it vulnerable.

Dr Stuart-Smith said while the removal operation from the bay was relatively straight forward, the initial decision to remove them was difficult.

“I think it was a proactive rescue operation that we haven’t really seen before in this country. And I don’t know that there are too many marine examples worldwide,” she said.

“But there’s that increasing pressure on being able to act very quickly, particularly in terms of climate change impacts.”

It’s an approach that Dr Stuart-Smith said may become more common.

“I think it’s definitely novel. And I think it’s something we’re probably going to see more of in the future.”

Researchers ‘disappointed’ by deaths in captivity

Dr Andrew Trotter leads the conservation breeding project for the fish at IMAS and said he was glad they had been returned to their natural habitat.

“They’re wild animals and belong in the sea,” Dr Trotter said.

While deaths in captivity are not uncommon — two out of four Maugean skates have already died in a captive breeding program meant to save it from extinction — Dr Trotter said he was disappointed by the mortalities.

“This has highlighted the urgent need to better understand disease in this species.”

Dr Trotter said the four handfish that remained in captivity as part of the captive breeding program would help improve the genetic diversity of the population.

Focus shifts to habitat restoration

Lessons learnt from this trial will inform future conservation effort, potentially making interventions smoother and easier.

But the pressure of being the custodian of a fragile and remarkable animal still weighs on Dr Stuart-Smith.

“Our red handfish [conservation] work has been operating for the past five years where we’ve had this captive population and captive breeding occurring with the intent to bolster wild populations,” she said.

“So, we’ve already held that sort of mentality around being custodians or carers for the species.

“Now we refocus — we’ve got funding, thankfully, from the Foundation for Australia’s Most Endangered Species (FAME) to continue monitoring of the wild population.”

Dr Stuart-Smith said her team was now “firmly focused” on trying to restore and recover the red handfish’s habitat to ensure the species’ survival.