Every year, anglers catch tropical pacu, a vegetarian cousin of the piranha, in waters across the United States. For example, Holley Luft caught a 14-inch specimen in Michigan’s Lake St. Clair last July. They do so because irresponsible aquarium owners release them into lakes and rivers.
And more infrequently, for the same reason, anglers catch one of those fish with the razor-sharp teeth and a reputation for tearing flesh to shreds. That’s what happened late this spring, when Roger Headley pulled a piranha from Arkansas’ Lake Bentonville.
“I about messed my pants,” Headley said.
Arkansas Game and Fish Commission confirmed the catch and a spokesman said the fish was “probably a pet that got too large or difficult to manage.” He added that a variety of exotic species are found in state waters annually, including an octopus in Lake Conway in 2003.
Another piranha was caught at Hickory Creek Marina on Beaver Lake in 2014. Several have been found at Missouri’s Lake of the Ozarks since 2007.
In trying to allay fears, especially regarding piranhas, fisheries managers always are quick to point out these tropical invaders can’t overwinter and reproduce because they are intolerant of cold.
But that is not always the case, as B.A.S.S. Times revealed two years ago. The Jack Dempsey, a tropical predatory fish related to the peacock bass, is thriving in South Dakota’s Fall River. How is that possible?
“The hot springs in the river makes it perfect for cichlids,” Mike Smith, aquatic nuisance species coordinator for South Dakota Game, Fish and Parks, said in 2012. “We first found a Jack Dempsey there in 2009. Then, two weeks ago, we found multiple-year classes.”
“And there’s no way that the fish could have gotten there except aquarium release.”
In that case, the Jack Dempsey’s impact on native species likely will be minimal. Few other predators live in the shallow water, and forage species gobbled up by the aggressive cichlid can be replenished from populations outside the range of the hot spring’s influence.
But the discovery was significant because it confirms that exotics can use thermal refuges provided by springs or warm-water releases from power plants to survive in cold climates. Will pacu be the next South American exotic to find such a hospitable environment?
Or maybe piranha?