Marine fish driven to extinction by humans

Last year, the Java stingray became the first fish to be declared extinct as a result of human actions. Could there be more soon?

In the bright coastal waters of Australia, Julia Constance has often searched for mushrooms. These flat-bodied fish are like miniature stingrays, but different. Stingarees are smaller – and more elusive. “They’re very cold,” says Constance, a PhD candidate at Charles Darwin University in Darwin, Australia. They don’t swim alongside you like manta rays, she explains, as she recalls snorkeling expeditions that rewarded her with sightings of the usual pale ghostly plane.

“Once you’re good,” says Constance, “you can spot them when they’re completely buried under the sand.”

But there’s a mushroom she’ll probably never see alive, bouncing around on the seabed. Last December, Constance and colleagues published an assessment of the mysterious Java stinagree, a species undocumented by scientists for more than 160 years. It was gone, Constance and her colleagues declared. And worse, the Java stingray is the first marine fish to be considered extinct due to human activity.

This was seismic news and not undisputed. “It’s a really big call,” says Constance. “She really ruffled quite a few feathers.” The Java stingaree is one of those extremely enigmatic species that scientists know very little about. There is only one museum specimen – purchased from a German zoologist in a fish market in Jakarta in 1862. How, some observers asked, could we be sure that this was indeed a distinct species and that humans were responsible for its extinction?

That single specimen, held by the Natural History Museum in Berlin, is only 33 cm (13 in) long, including its tail. Her skin color has likely faded to what is now a pale shade of brown. It’s a female, but we don’t actually know if it’s a juvenile or an adult, says Constance. To find out, you have to cut it open and examine its reproductive organs. Since it’s the only specimen, that won’t happen, she adds. But still worth mentioning. “It’s really, really round for a rogue,” says Constance, referring to the animal’s disc-like body.

It is so different from any other hornbill, and associated with an area not known to harbor other stinging species, that we can be sure it is not a hybrid species, Constance explains. Although she adds that she was only able to inspect the specimen from photos because her research took place at the height of the Covid-19 pandemic, which prevented her from traveling.

As for the judgment that the species is now extinct and, moreover, that humans are to blame, Constance says that she and her team relied largely on data on fishing industry activity from Indonesia. This included data from extensive surveys carried out at landing sites – places where fishermen bring their catch ashore, usually to sell it – on site since 2001.

“There was a really, really big push to start documenting the catches of sharks and rays across Indonesia,” says Constance. “Java stingaree would be really easy to identify if it was there.”

By entering all the information they could find about the stingray into data analysis tools provided by the International Union for Conservation of Nature (IUCN), Constance and her colleagues found that the organization’s models were 93.5% certain that the Java stingray was disappeared. IUCN, an international organization that collects and provides information on the status of species in the world, published the results of the assessment on its website.

Diego Biston Vaz, senior curator of fish at London’s Natural History Museum – who was not involved in the assessment – ​​also cites Indonesian survey data collected since 2001 and says it “makes sense” that the IUCN was in able to declare the fish officially extinct recently. year.

And yet, it remains surprising to think that this is the first official marine fish extinction linked to human activity. Humans have caused the extinction of at least 198 species of spines since 1900 – including various types of fish found in rivers and lakes. But these species are more or less restricted to land or freshwater – ecosystems that tend to bear the brunt of our activities. In contrast, the seas of the planet are large and we have just started exploring the seabed in fine detail.

One possible reason that the Java stingray is the only marine species to be declared extinct is that marine habitats offer a much better chance for organisms to escape our impact by moving to untouched areas, says Catherine Macdonald at the University of Miami Shark Research and Conservation Program.

“Even when we’ve greatly impacted coastal environments, there are still parts of the ocean that historically haven’t been as accessible to humans,” says Macdonald.

Macdonald adds that sharks and rays take a long time to reproduce. Close relatives of the Java teal can only produce offspring once or twice a year, at best, says Constance. This means that any disruption to the species population by human impacts – such as fishing – can have a devastating effect.

Constance suggests that the Java whelk was confined to a relatively small area subject to considerable fishing activity. I wonder if it is possible that some disease or other natural event is responsible for the decline of the species. “We can’t say 100%” one way or the other, she admits, though she adds, “I think, to a large extent, it was us.”

However, not all declarations of extinction stand. Constance mentions the case of smooth handfish, from the coastal waters of Tasmania. It was actually the first fish declared missing in modern times, in 2018. However, a reassessment in 2021 determined that the data used to support this statement were insufficient. The IUCN then relisted the status of the fish as “unknown”.

We have to set a very high bar for concluding that a species is extinct, points out Riley Pollom, species recovery program manager at the Seattle Aquarium, because the moment it’s considered extinct, all conservation efforts stop. If you mistakenly declare a species extinct and measures to protect it evaporate, then – ironically – it may actually become extinct as a result of this change in status.

And while scientists can be fairly certain about the Java stingray extinction, Pollom says, he points out that the sheer scale of the world’s oceans means experts may have missed other extinctions linked to human behavior. “Basically, there can be a lot that slips by us without us knowing,” he says. (Read more from BBC Future about unknown species in the deep ocean.)

Constance’s search for the Java stingaree is far from over. For one thing, she keeps an eye on the museum’s collections just in case another historical specimen turns up. One particular species she has been studying recently, a critically endangered type of ray called Red Sea Torpedoit is preserved in the museum – but there are only three known specimens and for years one of them was missing. A curator only informed her last year that they had found it again, she says.

Plus, this summer Constance was finally able to travel to Jakarta herself to observe operations at the two main fish landing sites there, having previously been unable to do so during her research due to travel restrictions. Covid-19. She and her colleagues searched the piles of freshly caught fish for species of sharks and rays. And she couldn’t help but wonder if she could spot a Java rogue in the crowd.

“It’s always in the back of my mind – what if someone finds it?” says Constance. But despite the harshness of her and her colleague’s statement in 2023, she would not be upset or disappointed if the disappearance was a mistake.

“We want these things to survive into the future,” says Constance. “It would be great if someone found it one day.”

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