The effects of a peacock bass invasion, 45 years later

The peacock bass has decimated native species in Panama's Gatun Lake. Photo by Smithsonian Tropical Research Institute

PANAMA CITY, Panama, Dec. 12 (UPI) — Researchers have quantified the long-term effects of an invasive predator fish on native populations in Panama. The results aren’t good.

Peacock bass, Cichla monoculus, are good to eat and fun to catch. They’ve been exported across the globe to satisfy the appetites of sport fishermen, but fishermen aren’t the only hungry ones. Peacock bass are eager predators, and have been blamed for the disappearance of native fish in several bodies of water.

One of those bodies of water is Gatun Lake, one of the main channels forming the Panama Canal.

To measure the long-term impact of peacock bass on Gatun Lake, researchers at Smithsonian Tropical Research Institute decided to replicate a survey of native fish first conducted in 1973 — after the accidental introduction of peacock bass to the lake but before its explosion in numbers.

In 1973, STRI researchers Thomas Zaret and Robert Paine found peacock bass had extirpated 60 percent of the native freshwater fish species.

The new survey suggests the trend has continued and local species have failed to rebound, despite pressure from sport fishermen.

“Zaret and Paine recorded 12 native fish species in the Trinidad arm of Gatun Lake in 1972 before the peacock bass invasion reached that region of the lake,” Diana Sharpe, an STRI scientist and postdoctoral fellow Canada’s McGill University, said in a news release. “We recaptured only three of those species after extensive seining. Our study shows that despite the appeal of peacock bass as a sport fish, the introduction of a novel apex predator can have dramatic and long-lasting impacts on native communities, even in diverse tropical communities, which are sometimes thought to be more resistant to invasion.”

Other invasive species have found their way into Gatun since the initial 1973 study, but research suggests most of the ecological damage is being done by peacock bass.

Researchers compared the numbers of native species in two lakes invaded by peacock bass, Gatun and Alajuela, with the numbers of native species found in Lake Bayano, a body free of peacock bass. Despite hosting other invasive predators, like the Jaguar Cichlid, Parachromis managuesis, Bayano hosts a greater abundance of native fish.


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