Is this massive super-predator with the head of an alligator the secret weapon against invasive Asian carp?

It’s a prehistoric-looking river giant that can grow almost three metres long and has a mouth filled with teeth that would do a vampire proud.

It plied US waters from the Gulf of Mexico to Illinois until it disappeared from many states a half-century ago.

Persecuted by anglers and deprived of places to spawn, the alligator gar — with a head that matches its reptilian namesake — survived primarily in southern states in the tributaries of Mississippi River and Gulf of Mexico after being declared extinct in several states farther north. To many, it was a freak, a “trash fish” that threatened sportfish, something to be exterminated.

But the once-reviled predator is now being seen as a valuable fish in its own right, and as a potentially potent weapon against a more threatening intruder: the invasive Asian carp, which have swum almost unchecked toward the Great Lakes, with little more than an electric barrier to keep them at bay. Efforts are now underway to reintroduce the alligator gar from Illinois to Tennessee.

“What else is going to be able to eat those monster carp?” said Allyse Ferrara, an alligator gar expert at Nicholls State University in Louisiana, where the species is relatively common. “We haven’t found any other way to control them.”

Alligator gar, the second-largest US freshwater fish behind the West Coast’s white sturgeon, have shown a taste for Asian carp, which have been spreading and out-competing native fish for food. The gar dwarf the invaders, which themselves can grow to 1.2 metres and 45kg. But the world-record alligator gar was 2.6m long and 149kg, though they can grow larger.