If you haven’t been living under a rock for the past couple of weeks, you’ve probably seen reports all over the international news of a “testicle-biting” tropical fish spotted in Swedish waters. There are two major problems with the focus of this coverage.
First, and most important, the whole story is a joke. Literally a joke. There are a few stories of the fish biting people floating around, but no one has yet been able to offer any proof of a confirmed case. Which isn’t surprising, since pacu fish, while related to pirañas, are actually herbivores. The professor who was quoted warning men of the dangers admitted in an email to CNN that the comment was an attempt at humor that was meant to draw attention to the problem of invasive species.
Other experts have backed him up, saying that the pacu fish’s crushing teeth are only used for eating seeds and fruit — and that human beings simply don’t move like fallen fruit bobbing on the water, even without a protective swimsuit. Either way, the tropical pacu is unlikely to survive the harsh Swedish winter, so if there are more of them lurking in European waters, they won’t be around for long.
The other problem with this coverage is it’s an easy way to get a sensational headline and a few laughs without talking about the very real issues posed by invasive species. These species cause real damage to the ecosystems they visit — and with no natural predators, there is often no easy solution to keep their populations in check.
This has happened more than once in Australia, with cane toads displacing native species across the nation and rabbits causing severe soil erosion by damaging native plant life. You can see similar effects in Guam, where tree snakes have eradicated 10 out of 12 native bird species. Even the US state of Illinois has struggled in recent years with invasive Asian carp, which compete with native fish for resources.
Dealing with invasive species forces us to confront a series of difficult questions. Is it wrong to try to eradicate a species from a country or continent? Is there any way to kill them humanely in large enough numbers to make a difference? Should they be treated the same way as other “pest” animals, or do their unchecked numbers call for a more aggressive approach? And should invasive species be handled differently than other animals under the law?
Unfortunately, there are no easy answers. In some cases, mass poisonings may be the only solution. In others, the easiest way to keep a species in check might be erecting physical barriers, like Australia’s rabbit-proof fence. As trade and tourism become increasingly global, the problem of invasive species is only going to become more complex with time.
A cane toad / photo by Brian Gratwicke