Fear and controversy continue to surround the giant Asian carp as they move closer to the Great Lakes. While there is no ideal solution for the problem, the question in the minds of many; Is Rotenone treatment a viable option to prevent the entry of this aggressive species into the Great Lakes?
From his office in Ottawa County, Southwest District Extension Educator for Michigan Sea Grant, Dan O'Keefe, Ph.D, said, "The question often comes up; How can we keep them out? We probably can't keep them out. We're talking about limiting the risk of them becoming established, and there is a difference."
"There are two different species of the Asian carp," says O'Keefe, "One of them has already been recorded in the Great Lakes since 2000, in Lake Erie, the big head (Asian) carp."
"We know that every time an invasive species shows up in the Great Lakes," says O'Keefe, " and there are over 180 of them, every one could be the next really bad one. But the way invasives actually work, it is just not a foregone conclusion that just because they get here, they are going to really take off. Sometimes they have to be introduced multiple times and have to reach some kind of critical threshold.That's crucial, in understanding where we need to go with the Asian carp now."
Last week the U.S. Army Corps of Engineers released the findings of a research study conducted by researchers at University of Notre Dame showing eDNA evidence for the Asian carp north of the barrier in the Chicago Sanitary and Ship Canal. This would suggest the monstrous carp may have broken through the electric barrier set up by the U.S.Army Corps of Engineers to prevent their entry into the Great Lakes.
A short time later, the Illinois Department of Natural Resources announced its plan to dump Rotenone, into the canal between Romeoville and the Lockport Dam in early December while the barrier undergoes maintenance..
Responding to the Illinois DNR's announcement, O'Keefe said "I think that when people hear that they are going to use Rotenone, which is a powerful fish toxin, the idea is that they are going to kill every single fish. Right now, Rotenone is being used in conjunction with the barrier maintenance."
"They are using Rotenone at the barrier, says O'Keefe, "because when they turn the barrier off, there is basically an open door. The idea is not to kill everything that has gotten through. The point is to try to limit the big population that resides downstream of the barrier and preventing that from moving up further. It is just a safeguard when they have to take the barrier down."
"Nowadays, fisheries managers are not prone to making that decision at all." He stressed, " These are professionals who spend their lives working with fish. If they have to go kill a bunch of fish, they're not going to like doing it. It's judged as necessary to keep the carps from basically getting through the open door from the river system."
O'Keefe indicated he had not been in contact with the Illinois DNR, but it was his understanding that they would be using a process called, electro-fishing first. "Electro-fishing is a technique biologists use to promote fish movement towards a boat," says O'Keefe, " where they are stunned and netted alive. It's a nice technique to use because, if done properly, it is pretty harmless for the fish, as well. They are going to try to get the fish there that are game fish and move them to another area before they drop the Rotenone."
Research to find a Rotenone concentration that would be more toxic to the Asian Carp, was inconclusive. Following the Rotenone treatment, the area is then neutralized with a potassium based substance.
The Asian carp have caused havoc in the Mississippi River region where they have made it difficult for some of the native sport fishing species to survive in their quest for food. They have also become a threat for boaters because of their aggressive nature and ability to jump several feet into the air. It is not uncommon for boaters to report seeing hundreds of the giant carp jumping while traveling short distances.
Theories are mixed as to how the Asian carp were first introduced into the U.S. No one is rushing to the podium to admit responsibility. Some analysts speculate the carp were originally imported by catfish farmers in the 1970's to clean up their ponds. Several species of the fish later found their way into the Mississippi River and its tributaries in the 1990's, when there was heavy flooding.
An audience of thousands will be watching as officials move forward in the Asian carp management process.
The second in our two-part series on the Asian carp continues on Thursday.
For more information:
http://www.miseagrant.umich.edu/
http://www.epa.gov/glnpo/invasive/asiancarp/
http://detnews.com/article/20091121/METRO/911210364/Asian-carp-nears-Lake-Michigan
http://www.lrc.usace.army.mil/pao/calsag_eDNA.pdf
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