Lionfish get fat in the land of plenty


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Invasive lionfish in the Atlantic are eating so much they're becoming obese, writes Nathan Hill.

Oh, 'Murica. With your bounteous hypermarkets and diabetes-inducing lust for high fructose corn syrups. It’s almost as though anyone who lands on your shores has no choice but to balloon in girth.

It turns out that humans aren’t the only ones pushing the 'land of plenty' to its absurd extremes. Another invader, offshore rather than land based, is finding pickings so rich that it’s making itself ill. Pterois volitans, the Common lionfish, is eating itself to death.

Lions aren’t native to North America, and it’s a story that we’ve covered many, many times. We’ve looked at sharks trained to eat lions, and groupers guzzling them down by the dozen.

We’ve reported on their unprecedented reproductive efforts and even specially constructed traps Hell, we’ve even alluded to lionfish recipes, and pointed out how fishermen have been given the carte blanche to massacre as many of these venomous rotters as they can before they irreversibly screw up the American ecology.

It turns out that lions have gotten so comfy in their stateside home that they’re now subjecting themselves to a lifestyle hazard that has been quite literally increasing in humans (you could say has been increasing humans) over the last few decades — obesity.

Yup, the lionfish have now got it that good, and their prey are so oblivious to the threat that lions present, that they’re developing fatty livers and huge packages of interstitial fat.

Lionfish are well adapted to eat. The gob is huge, and acts as the portal to a stomach that can swell to 30 times in size. Anyone who’s kept them will know just how much they can pack away, stuffing their little plumper mouths until they end up panting on the base of the tank, six or seven smelt tails poking out from behind their lips. Even the wild ones have been seen smacking down two fish a minute during feeds.

The fact they’re getting so portly is a real worry, hankering as it does at just how much they’re eating.

In other regions, lionfish impact is recorded. As a ballpark figure, the evidence suggests that lion populations get through about 450kg of prey fish per acre per year. That’s a lot of fish, in fairness.

To get obese, fish need to consume much more than that. Acquiring the kind of bulk the yankee lions are getting could involve up to 7.5 times their usual dietary input. If 450kg of fish is a lot, then over 3,000kg is, if you’ll excuse the pun, an even harder figure to digest.

Ah, so what? Aren’t we eating the things now? Surely we can get all apex predator on their invasive behinds?

Well, the future’s not looking so bright there. Although it’s still fledgling days, the writing on the wall is that lionfish flesh might be getting struck off the menu for health reasons. It turns out that testing could show the presence of ciguatoxin in lion flesh. That’s not great stuff, working its way into the food chain until it hits our plates. It starts off as tiny dinoflagellates on the reef, goes through the channels of building up in predatory fish flesh, and then when it gets into our weedy human bellies causes paralysis and full on heart issues. You really don’t want it in you.

So there we have it. The lions are not just breeding, but killing themselves into the bargain, killing everything around them, and being obstructively unpalatable in the process.

It’s almost enough to put me off of my supersize Big Mac meal.

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