The smooth handfish (Sympterichthys unipennis) was declared extinct by the International Union for Conservation of Nature (IUCN) in March of this year. Only one specimen has ever been known to science, collected by the French naturalist François Péron in 1802. However, the fish has not been seen since then, even after thorough regional assessments.
The smooth handfish is thought to have once been common in shallow waters around Tasmania and the south coast of Australia. It was a bottom-dweller and, as with other handfish species, it was named for the specialised fins that the fish use to walk across the seafloor.
Several other handfish species are also under threat and could soon suffer the same fate. In 1996, the spotted handfish (Brachionichthys hirsutus) was the first marine fish to be declared critically endangered, though the red handfish (Thymichthys politus) and the Ziebell's handfish (Brachiopsilus ziebelli) have since followed suit. In addition, there are seven species of handfish which have not been seen in over 20 years.
So, what caused their decline?
As Australia and Tasmania were colonised, it is likely that exploitation of the surrounding waters caused a significant impact, with sensitive ecosystems changing at an unexpected rate. Dredging for scallops and oysters, sediment runoff from industrial activity, and climate change would all have been contributing factors and, even now, ecosystems across the region continue to be impacted.
"About 40% of shallow reef species in southern Tasmania are showing rapid population decline, the whole marine system in the south-east has changed substantially in the last 100 years," Professor Graham Edgar, a marine biologist at the University of Tasmania, told the Guardian.
Why does it matter?
The loss of the smooth handfish is likely an indictor of a much larger issue.
Ocean warming, caused by climate change, makes life extremely difficult for species that require a cold water habitat, as warm water continues to spread further and further south. As a result, many other vulnerable species in the waters around Tasmania could suffer the same fate as the smooth handfish and are currently threatened with extinction.
In addition, as it is so difficult to accurately assess and monitor marine species, it is likely that the smooth handfish actually went extinct decades before this year's official declaration. Knowing that, we have to ask ourselves, how many other fish species may have come and gone without our knowledge?
It is impossible to survey the entire ocean, making it highly likely that a number of marine species have gone extinct before they could even be discovered. This lack of data means that we are unable to evaluate the true extent of biodiversity loss in the oceans. As a result, it is not possible to implement the necessary conservation efforts in time.
So, the official listing of the smooth handfish as extinct highlights a larger issue that is happening right now in our oceans. If it is assumed that marine species are going extinct at a similar rate to terrestrial ones (as the evidence suggests they are), then ocean biodiversity is under significant threat. We need to act now to reduce the current impacts on marine ecosystems before it is too late and more species follow the smooth handfish into extinction, including those that we may not yet be aware of.
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