In May of this ‘exciting’ year of 2020, it was widely reported that the Smooth Handfish (Sympterichthys unipennis) was declared the first species of bony fish to go extinct in modern times. Without a doubt, it is sad that a creature described as having a ‘punk rock hair-do’ has been relegated to a single, discolored specimen on the shelf of a natural history museum discolored specimen on the shelf of a natural history museum. However, it is also striking that this is the first member of one of the most diverse of all animal groups to go extinct in modern history. How can this be?
The era in which we’re currently living, called the ‘anthropocene’ due to the ubiquitous effects of human activity on the rest of the planet, is a period punctuated by extinction. Species have been going extinct faster in the last few thousand years than they have any time since the extinction of the dinosaurs some 65 million years ago (the ‘K-T boundary’ extinction event) (1). Famous victims include the Dodo (Raphus cucullatus) and the Passenger Pigeon (Ectopistes migratorius), which vanished in the face of expanding civilization.
But what happened in the ocean? We often hear stories of imposing fleets hunting down whales or coldly harvesting ever last cod out of the sea to feed humanities insatiable greed. So why don’t hear of the Minke Whale (Balaenoptera spp.) or the Atlantic Cod (Gadus morhua) going extinct?
The marine world isn’t completely lacking in species extinguished by the impact of humankind. Take the Steller’s Sea Cow (Hydrodamalis gigas) for example; this massive dugong of the cold North Pacific lasted a mere thirty years from when it was discovered before being harpooned out of existence by sailors and explorers in the late 18th century.
Fast-forward two hundred fifty years and we have the first declaration of a fish going extinct. What then makes marine species so special? Are they somehow ‘extinction-resistant’ or is something else going on?
The answer is, as usual, is not so simplistic.
First, we without a doubt know less about marine ecosystems compared to their terrestrial counterparts. So due to the simple fact that the vast and voluminous ocean is a challenging and resource-intensive place to monitor, species may have gone extinct without modern science ever even knowing they existed in the first place.
A second important factor is that the ocean is a highly interconnected system, which has allowed many marine species to develop extensive ranges covering hemispheres and in some cases nearly the entire ocean.
Thirdly, humans live on land. There is a growing body of evidence to suggest that human expansions, such as the arrival of humans in Australia some 65,000 years ago, directly sped up the rate of extinction in those places, either through hunting or habitat modification (1).
Until relatively recently, most human resource extraction in the sea was limited to the coast, and until the industrialization of whaling and sealing in the 19th century it was usually small in scale. Therefore, much of our impacts on marine species are relatively recent, compared to terrestrial species (2).
In the case of the Smooth Handfish, despite being reportedly common, it was coastal and restricted to a specific reef habitat around Tasmania making its existence susceptible to sudden changes. The exact causes of this extinction are unknown, however it shares the important similarity with many other extinct species of being limited to a small area or a specific, vulnerable habitat.
Although we don’t currently have evidence of any formerly widespread marine species going extinct in the Anthropocene, extirpations (local or regional extinctions) are known.
Take the Gray Whale (Eschrichtius robustus). Until the late 19th century, the Gray Whale existed throughout the North Atlantic and Pacific Oceans. During the period of industrial whaling, whalers took advantage of this species’ habit of keeping close to the coast, especially during calving (birthing) season. By the early 20th century, the population of Gray Whales in the North Atlantic vanished, leaving only the Pacific whales to carry the proverbial torch forward.
Interestingly, recent archaeological evidence collected at ancient Roman fish processing sites in the south of modern-day Spain, suggests that the Roman fishing industry may have in fact extirpated the eastern portion of the Atlantic Gray Whale population, which calved in the Mediterranean (3).
So it appears that the cumulative effects on the once common Gray Whale have had their impact, with one local population disappearing, then another, until an entire ocean is devoid of a formerly common species.
Deep-sea mining, long-distance fishing fleets, and trans-oceanic shipping are just a few of the faces of growing human endeavor in the global ocean (4). Few places on our planet remain outside our realm of influence; so the warning of the Smooth Handfish seems to rings clear.
How many more will follow?
References
- Pievani, Telmo. “The sixth mass extinction: Anthropocene and the human impact on biodiversity.” Rendiconti Lincei 25.1 (2014): 85-93.
- McCauley, Douglas J., et al. “Marine defaunation: animal loss in the global ocean.” Science 347.6219 (2015).
- Rodrigues, Ana SL, et al. “Forgotten Mediterranean calving grounds of grey and North Atlantic right whales: evidence from Roman archaeological records.” Proceedings of the Royal Society B: Biological Sciences 285.1882 (2018): 20180961.
- Halpern, Benjamin S., et al. “A global map of human impact on marine ecosystems.” science 319.5865 (2008): 948-952.