A few handfuls of fish sitting in bags filled with seawater represent almost half the world’s known population of the species. We have spent the past year carefully raising them from wild-collected eggs. Now, releasing them back into the ocean, represents a monumental step in saving this curious little creature from extinction.
The red handfish (Thymichthys politus) is an evolutionary oddity. It is a relation of the anglerfish family, known for their bizarre biology. The red handfish is no exception.
With a down-turned mouth, bright red mohawk, fluffy pom-pom on its head, and over-sized, hand-like fins, it appears to have crawled straight out of a child’s fairy tale. A critically endangered Tasmanian fish that moves by walking clumsily on the seafloor using its “hands”, it spends most of its time hiding under seaweed or bumbling around amongst seagrass. Fully grown, it easily fits in the palm of your hand. Red handfish move very little. An ambush predator they prefer the sit-and-await approach to gulp unsuspecting prey that swim by.
This species is thought to be a remnant of an ancient lineage with a wider historical distribution, but in modern times it is a “short-range endemic” with very localised distribution. When faced with habitat loss or degradation, it cannot simply disperse to new areas; it has evolved to walk on the seafloor and therefore has little ability to move, even to the next patch of suitable habitat.
In addition, they have no planktonic (free-swimming) larval stage that many species use for dispersal, so populating new areas is difficult. This combination of characteristics raises a red flag for extinction risk when habitat loss is involved. The red handfish faces a torrent of threats centred around declining habitat due to human impact. Degraded seaweed and seagrass (which are important for shelter and spawning substrate), ever-encroaching sea urchin barrens, the unknown impacts of a changing climate, and multiple other stressors combine to threaten it with extinction.
“Head-starting” red handfish is a conservation strategy initiated through the Institute for Marine and Antarctic Studies (University of Tasmania) and CSIRO. With fewer than 100 adults thought to remain in the wild, immediately boosting their population is crucial to their very existence. This is a short-term measure to afford us the time we need to implement long-term restoration.
Head starting involves bringing fertilized eggs into captivity and rearing the resultant juveniles to a release age, where they are more likely to survive to breed themselves. Unfortunately, it is also a strategy loaded with risk and, amplified by critically low population size, it means there is little margin for error.
Collecting eggs, hatching fish, raising young, keeping them alive and healthy in captivity – each step is fraught with unknowns, and threatened to derail our entire program.
Even though they were cared for by a team of highly trained aquaculture biologists, experienced in rearing species with far more complex needs, there was an unspoken burden and pressure that came with trying to help a species on the brink. A year of care also provided time to become attached to these fish and all their little quirks. We watched them grow from the size of a rice grain to more than 5cm, witnessed their unique markings appear, observed them walking around, rumbling with each other, exhibiting curious little fin gestures – presumably the handfish equivalent of “Hey, you’re in my face” – that was often directed at the team peering in at them.
After all this, and given the importance of the occasion, we perhaps imagined something more ceremonious around their return to the ocean. Instead, we placed the fish, these hopefuls, critical for preserving an entire species, into bags and transported them to the site in a portable cooler packed with old newspaper and ice-bricks. No fanfare, just a 45-minute car ride, followed by a 10-minute boat ride to the site – which, while in the moment, appeared to be an eternity.
A team of divers converged at the side of the boat carrying the fish. Each dive pair was handed two bags of fish, and we slowly descended together the few metres to the seafloor, clutching the bags like our lives depended on it. Carefully unravelling the ties that held the bags securely closed, we slowly poured out precious batches of little handfish onto the seafloor, and stayed to watch their first moments back in the wild. We waited, almost expecting some sort of signal or gesture, but of course they did what handfish do best – sat still, looking glum and unimpressed. We moved away, simultaneously hesitant to leave, but eager to let them settle into their new world.
In the days following the release, we dived the site to track their progress. We saw several individuals each dive, every time they had moved further from their release points, confirming they had survived the initial transition back into the wild.
Two months later we again dived one of the release sites. Two divers searched for hours along transect lines, moving slowly while painstakingly pushing aside swathes of seaweed, looking for a glimpse of red. Elation is a difficult emotion to convey under bulky dive masks and dive gear, but on finding two small juveniles, that was exactly the sentiment. We felt immediately they were our handfish, but we are scientists so it wasn’t until we had compared markings with photos prior to release that we celebrated the sightings.
The fish looked healthy; they were behaving like they were supposed to – overwhelming assurance that the strategy was appropriate, and we could make a difference.
It created a sense of accomplishment, relief and, most importantly, hope.
Where to from here? Monitoring their survival over time is fundamentally important. We need to repeating the head-starting, continue to work on restoring their habitat, and chase funding to keep this important conservation work going.
Dr Jemina Stuart-Smith is a marine biologist at the Institute for Marine and Antarctic Studies, University of Tasmania, and the CSIRO. She coordinates the Handfish Conservation Project within the Marine Biodiversity Hub of the National Environmental Science Programme in Australia. Her work focusses on aiding the recovery of critically endangered handfish species in Tasmania and restoration of their habitats. She has a keen interest in marine conservation and science education, and is a member of the National Handfish Recovery Team.
Dr Andrew Trotter is a Tasmania-born biologist currently working at the Institute for Marine and Antarctic Studies, University of Tasmania. His PhD study was on rearing marine fish larvae. He worked post-doctorate studying mutant zebrafish, and spent several years as an environmental consultant based in Perth assessing risks to troglofauna and stygofauna in the Pilbara. He is a naturalist at heart with a deep interest in conservation, and is a member of the National Handfish Recovery Team.