Invasive Asian Carp Survive Harsher Conditions than Expected: Bad News for Freshwater Rivers

Asian carp, the invasive species that has plagued Lake Erie and other freshwater sources for years, may be able to spread further and faster than first thought. Researchers have found that this fish can survive harsher conditions than once believed--a bad sign for the future of freshwater ecosystems.

Asian carp are a species native to China. They were first brought to the U.S. in the 1970s in order to control algae problems in Arkansas aquaculture ponds. Unfortunately, several of the carp escaped during flooding conditions and started reproducing in the Mississippi. They eventually journeyed north, finally landing in Lake Erie and spreading out to Midwest rivers across the United States. Weighing up to 60 pounds with a silvery sheen, they leap out of the water when startled and can cause injuries to boaters and others using rivers and streams. Since this hearty species can reproduce rapidly, it could overwhelm and outcompete native populations of fish and cause drastic consequences for local ecosystems. Currently, there are worries that the fish may be in Lake Erie where traces of the fish's DNA were recently discovered.

The new study, conducted by Purdue University researchers, shows that Asian carp are spawning in rivers that were at first thought too narrow or two slow for species survival. They also found that the fish spawned far longer into the season than first expected; while previously thought to have ended sometime in July, researchers discovered that the season continued as late as September.

Previous models of when and where Asian carp might spawn have been heavily based on information gathered from native habitats in Asian rivers. The latest findings, though, show that this information doesn't hold true from the United States. In particular, the researchers examined how well the Asian carp fared during last year's severe drought. At that time, stream flows were limited; even so, Asian carp eggs were still found in narrow portions of the Wabash River, once thought incapable of supporting the species.

"The reason truly invasive species are so successful is because they overcome obstacles," said Reuben Goforth, one of the researchers, in a news release. "When you base their limitations on what happens in their native ecosystems, it's a good start. But it may be a good idea to go back and take this new data to recalculate more precise limits based on these new understandings."

The researchers plan to continue examining the Asian carp and will attempt to determine exactly what causes it to adapt to conditions that aren't found in their native habitats.

The findings are published in the journal Freshwater Biology.