What is the asian carp?
What sort of threat does this fish pose?
How did it they here?
What is eDNA testing?
So we haven't really found the carp, just their DNA?
What is this I hear about using fish poison? Why is this necessary?
Will Rotenone kill everything?
Is Rotenone dangerous?
Is poison our only option?
What is the Chicago Sanitary and Ship Canal?
Can the artificial connection be closed?
The term "Asian carp" refers to four different species of fish: the bighead, black, grass and silver carp. The bighead and silver carp are biggest threat to the lakes, growing to over 60 pounds (27 kilos) and greater than 3 feet in length (1 metre). They feed on zooplankton and algae and can eat tremendous amounts every day. Black carp consume primarily mollusks, and threaten native mussel and sturgeon populations. They can grow to seven feet in length and 150 pounds.
These fish are voracious filter feeders that can quickly come to dominate a waterbody. The bighead carp can consume 40 per cent of its body weight each day, while the silver carp's tendency to jump out of the water when startled makes them a hazard to boaters. They would cause irreversible harm to the Great Lakes by consuming large quantities of algae and zooplankton, muscling out native fish populations. The estimated impact to the recreational and commercial Great Lakes fisheries would reach to over $4.5 billion.
The fish were imported in the 1970s and used extensively in the southern United States for aquaculture operations. However, flooding in the early 90s allowed them to escape their pens and migrate into the Missouri and Illinois rivers. They have been working their way up toward the Great Lakes, and risk entering through the Chicago Sanitary and Ship Canal, an artificial connection between the Mississippi and Great Lakes basins.
Environmental DNA testing (eDNA) was developed at the University of Notre Dame to improve monitoring of invasive species. All fish, including Asian carp, release DNA into the environment. The presence of individual species can be detected by filtering water samples, and then extracting and amplifying short fragments of the shed DNA. The objective is to use eDNA testing as an early detection tool to identify Asian carp locations. For more information on eDNA read this U.S. Army Corps of Engineers factsheet (pdf).
Asian carp are still below a threshold of detection using traditional fishing gear. Electro-fishing is successful in detecting bighead and silver carp when they are in high abundance. The Chicago Sanitary and Ship Canal is, in some places, nearly 30 feet deep, which is another disadvantage to using traditional sampling methods. In the early spring and late fall, the water is cooler and produces less algae (a main food source of bighead and silver carp diets), and the fish tend to reside a bit deeper than they would during warmer months. With decreased metabolism (not as much food), they are also less active and therefore harder to detect.
The presence of carp DNA is enough to warrant swift action in protection of the world's largest freshwater ecosystem.
The electric barrier is due for maintenanc eand needs to be temporarily disabled. To prevent the Asian carp from bypassing it, Illinois Department of Natural Resources planned to use a treatment of Rotenone to kill all fish within a certain distance of the barrier, as well as using a smaller treatment by the O'Brien Lock.
Rotenone is derived from several tropical and subtropical plants in the bean family. It has been used in North America since the 1930s in ponds and lakes for fish sampling and to completely eradicate undesirable fish populations. I thas been approved for fishery use by the U.S. Environmental Protection Agency.
Rotenone affects all species of fish, although susceptibility to the chemical varies between species. The chemical inhibits a biochemical process at the cellular level making it impossible for fish to use oxygen in the release of energy needed for body processes. Rotenone is non-persistent, so there is no accumulation in the water, soil, plants or surviving animals. The breakdown process is very rapid. Ultimately, rotenone breaks down into carbon dioxide and water, two common substances.
In 2007 the U.S. EPA completed an evaluation of the human health and ecological risks associated with rotenone. In that evaluation, EPA concluded that rotenone could be used safely for fish management if used properly. For more information on the evaluation download this EPA report (pdf).
Rotenone affects all gill-breathing organisms. There are currently no toxicants that affect only Asian Carp. If used correctly rotenone does not pose human health hazards or significant detrimental effects to domestic animals, other wildlife, and aquatic or terrestrial vegetation.
Rotenone appears to be the most effective option for eliminating the Asian carp from an area of the canal. However, it should be considered an emergency measure, not a long-term management tool. The ecological integrity of the Great Lakes cannot be maintained through the regular application of a toxicant. Rotenone is a viable option for pushing the Asian carp back while a longer-term management plan is put in place. This plan must include the ecological seperation of the Great Lakes from the Mississippi basin.
The Chicago Sanitary and Ship Canal is an artificial connection between the Great Lakes and Mississippi basins. During the late 1800s Chicago suffered severe water quality problems, and a consequently regular public health emergencies when sewage waste was drained into Lake Michigan. The sewage outflows were near to the drinking water intakes. To overcome the health problems, the flow of the Chicago river was reversed, and a canal built to connect the river to the Mississippi basin.
Premlinary work has been done by the Alliance for the Great Lakes, exploring how the Great Lakes can be ecologically seperated from the Mississippi. Their report identifies five scenarios for complete or partial ecological separation of the basins. This would halt the transfer of Asian carp, as well as other invasive species, between the two watersheds and is a critical piece of invasive species prevention and Great Lakes restoration.
Technical information on this page is drawn from Ohio DNR, US EPA, Great Lakes Fishery Commission, U.S. Army Corps of Engineers