The US Geological Survey (USGS) recently released the results of a study that may have troubling implications for the future of Lake Erie. According to a press release distributed last week, not only would Asian carp species survive in the lake, high concentrations of algae—a preferred food source for Asian carp—would enable them to thrive.
“The water temperatures and algal concentrations detected in Lake Erie from 2002-2011 show that the bighead and silver carps could not only live in this environment, but could continue to grow,” the USGS stated.
“Throughout the lake, algal blooms encompass several hundred to several thousands square kilometers,” the agency added. “Specifically, the western part of Lake Erie has algal concentrations that are several times greater than what is needed for bighead or silver carp to survive.”
Fortunately, Asian carp have not yet arrived in the Great Lakes. They are not far, however, and the threat of their incursion has lawmakers scrambling for ways to keep this invasive species out. While Asian carp populations are still spreading in the Mississippi River and its tributaries like the Ohio River, the fish appear to be bottle-necked in the Chicago Area Waterway System, thanks to a series of man-made barriers. If Asian carp do get into the Great Lakes, officials fear that the fish may damage native fish populations like walleye and perch, threatening a $7 billion sportfishing industry.
Asian carp are already known to be adaptable, but the revelation that Lake Erie is already generously stocked with a carp-friendly food source is not good news. According to the USGS study, high concentrations of algae could increase carp growth dramatically. In just one year, a nine-pound silver carp can gain between 19 to 57 percent of its body weight. In the same time frame, an 11-pound bighead carp can gain between 20 to 81 percent of its body weight.
“Remote sensing imagery shows that Lake Erie has huge areas of available food that are often several times more concentrated than necessary for Asian carp growth, particularly in the western basin,” said USGS scientist Karl Anderson, who worked on the study.
From 2002 to 2011, algae concentrations in Lake Erie have increased from 273 percent to 411 percent, and it shows no signs of slowing down. It is believed that the algae growth was accelerated by phosphorus from detergents and other nutrients that had gotten into the lake.
Image courtesy US Fish and Wildlife Service