Grass Carp 'Officially' Invade Great Lakes
Spring 2017
By Dr. Patrick Rusz, Director of Wildlife Programs
The potential invasion of the Great Lakes by Asian carp has been a hot button issue for more than a decade with millions spent on monitoring and politicians debating how to stop the threat. Most of the attention has been focused on Chicago-area water
ways that could allow the dreaded silver and bighead carp—the best known of four feared exotic carp species—to move from Mississippi drainages into Lake Michigan. Meanwhile, as I reported in the July-August 2010 issue of the Wildlife Volunteer, scientists were aware that grass carp had already showed up in Lake Erie. Canadian scientists were expressing alarm, but until this year, federal and state fisheries biologists in the U.S. seemed indifferent or confused, noting that few were showing up and those were assumed to be sterile.
“They’ve just been humming in the background,” Marc Gaden, spokesperson for the Great Lakes Fishery Commission, recently told John Flesher of the Associated Press. “They haven’t
gotten a lot of attention. Once in a while one would get captured.”
In 2010 I learned from a 2004 publication authored by Ontario fisheries scientists that a six-year-old grass carp was captured near Cedar Point, Ohio in May 1995, and another adult was caught in Sandusky Bay, Ohio in June 2000. Then in October 2000, a three-foot long grass carp was captured in a commercial trap net in the shallow waters west of Point Pelee, Ontario. That was the first Asian carp recorded in Canadian waters. Researchers compared its growth and development with that of the 1995 (U.S. waters) fish using scale and bone samples. They concluded both fish were likely grown in ponds (a controlled environment) for a couple of years before being released or escaping into Lake Erie.
By Dr. Patrick Rusz, Director of Wildlife Programs
The potential invasion of the Great Lakes by Asian carp has been a hot button issue for more than a decade with millions spent on monitoring and politicians debating how to stop the threat. Most of the attention has been focused on Chicago-area water
ways that could allow the dreaded silver and bighead carp—the best known of four feared exotic carp species—to move from Mississippi drainages into Lake Michigan. Meanwhile, as I reported in the July-August 2010 issue of the Wildlife Volunteer, scientists were aware that grass carp had already showed up in Lake Erie. Canadian scientists were expressing alarm, but until this year, federal and state fisheries biologists in the U.S. seemed indifferent or confused, noting that few were showing up and those were assumed to be sterile.
“They’ve just been humming in the background,” Marc Gaden, spokesperson for the Great Lakes Fishery Commission, recently told John Flesher of the Associated Press. “They haven’t
gotten a lot of attention. Once in a while one would get captured.”
In 2010 I learned from a 2004 publication authored by Ontario fisheries scientists that a six-year-old grass carp was captured near Cedar Point, Ohio in May 1995, and another adult was caught in Sandusky Bay, Ohio in June 2000. Then in October 2000, a three-foot long grass carp was captured in a commercial trap net in the shallow waters west of Point Pelee, Ontario. That was the first Asian carp recorded in Canadian waters. Researchers compared its growth and development with that of the 1995 (U.S. waters) fish using scale and bone samples. They concluded both fish were likely grown in ponds (a controlled environment) for a couple of years before being released or escaping into Lake Erie.
Twenty-three grass carp have been found in Canadian waters of Lake Ontario since 2012, others in lakes Erie and Michigan.
In 2010, most Michigan fisheries biologists seemed to be unaware that grass carp had been found in Lake Erie. Two fisheries biologists in Ohio that I spoke with that year suggested the fish were likely planted by individuals in the Toronto area (e.g., “China Town”) where there are markets for Asian carp. In contrast, an Ontario biologist opined the fish came from ponds in Ohio where grass carp assumed to be sterile have been released into ponds for many years.
Now, moods of scientists and politicians about the grass carp in the Great Lakes are changing. A recent analysis has shown that some of the grass carp, now verified in lakes Erie, Michigan, and Ontario, are reproducing and have spread. “For the first time, we have a bi-national, peer-reviewed study by some of the best minds and practitioners in the field who have a consensus on what the risk is to the Great Lakes from grass carp, and it’s pretty substantial,” stated Gaden.
The analysis says it is very likely that grass carp will become established in lakes Erie, Huron, Michigan, and Ontario within 10 years unless effective steps are taken to stop them. Becky Cudmore, Asian carp program manager for Canada’s fisheries and ocean agency, and the primary author of the study, told the Associated Press, “Yes, they were showing up before, but now they’re starting the invasion process. They have arrived. Now is the time to act.”
Really? It seems the time to act was more like when the first grass carp were being released into the Great Lakes basin decades ago. For sure, the time to act was when the first ones showed up in Lake Erie. Exotic species can show up almost anywhere, and it’s not politically acceptable to start costly control programs until the threat is somehow verified. But a lot of sad stories about biological pollution start with a long wait until an invasion becomes “official.” When dealing with any type of Asian carp, it should not take a bi-national, peer -reviewed analysis, and a consensus among scientists to do what was called for in the 2004 Canadian report that noted: “…..prevention of introduction/ escapement through educating aquarists, fish farmers, and the general public is the most critical action needed to limit the future spread….”
Now, moods of scientists and politicians about the grass carp in the Great Lakes are changing. A recent analysis has shown that some of the grass carp, now verified in lakes Erie, Michigan, and Ontario, are reproducing and have spread. “For the first time, we have a bi-national, peer-reviewed study by some of the best minds and practitioners in the field who have a consensus on what the risk is to the Great Lakes from grass carp, and it’s pretty substantial,” stated Gaden.
The analysis says it is very likely that grass carp will become established in lakes Erie, Huron, Michigan, and Ontario within 10 years unless effective steps are taken to stop them. Becky Cudmore, Asian carp program manager for Canada’s fisheries and ocean agency, and the primary author of the study, told the Associated Press, “Yes, they were showing up before, but now they’re starting the invasion process. They have arrived. Now is the time to act.”
Really? It seems the time to act was more like when the first grass carp were being released into the Great Lakes basin decades ago. For sure, the time to act was when the first ones showed up in Lake Erie. Exotic species can show up almost anywhere, and it’s not politically acceptable to start costly control programs until the threat is somehow verified. But a lot of sad stories about biological pollution start with a long wait until an invasion becomes “official.” When dealing with any type of Asian carp, it should not take a bi-national, peer -reviewed analysis, and a consensus among scientists to do what was called for in the 2004 Canadian report that noted: “…..prevention of introduction/ escapement through educating aquarists, fish farmers, and the general public is the most critical action needed to limit the future spread….”