A little over two years ago a test of the Muskingum River using eDNA techniques showed positive results for Bighead Carp, one of several Asian carp species, and Northern Snakehead. Although the Ohio Division of Natural Resources (ODNR) and U.S. Fish and Wildlife Service sampled the Muskingum River extensively neither of these invasive species was actually caught. It may be that the highly sensitive eDNA technique picked up genetic material from bird feet or boat bottoms that traveled from areas where the invasive species were well established, but that has yet to be proven conclusively.
The OSUM Fish Division is currently carrying out a project to survey the Muskingum River watershed from top to bottom under the supervision of project leader Brian Zimmerman, with a grant from the Ohio DNR Division of Fish and Wildlife, overseen by Associate Professor and MBD director Meg Daly. Fifty-five sites above, below and in each of the nine pools between the locks and dams of the mainstem, and 5 each along the two major tributaries of the Muskingum River, Muskingum River lock and dam Photo from the Ohio Canal Society, the Walhonding and the Tuscarawas Rivers, will be sampled.
The sampling techniques will include
- Electroshocking: as the name implies, this technique involves the application of electrical current to stun fish, causing them to remain immobile for crew members with pole nets to retrieve them and place them in a large tub in the boat.
- Seining: The use of 6’ tall x 8’ wide seine nets by two or three people in this project to sample shallow areas.
- Benthic Trawling: We take an 18’ flat bottomed John boat with two 25 horsepower outboard motors and drag a small “otter” trawl net along the bottom of the river.
- Hoop Netting: This method uses 3 sets of large mesh nets supported by iron hoops. The hoop nets are left out for two days after which we return and remove the fish from the nets. Read more about this technique on our fish blog.
With all of the methods the catch is identified, counted, measured and weighed, and returned except for any invasive species we may catch (fortunately no Silver or Bighead Carp have been caught!…yet…). We see a very high rate of survival of the captured fish and these are returned to the river.
The project will extend over two years, from July to September of 2016 and 2017, and will culminate in a final report providing an assessment of the Muskingum River fish community. This information will provide a baseline for use in potential remediation efforts should the silver and/or bighead carp become established above the Devola Dam.
Technically all carp (Silver, Bighead, Grass, Common, Black, and Prussian carp, and Goldfish are the species currently established in the United States but there are at least four more – Crucian, Catlan, Mrigal and Mud Carp- are recognized as valid species) are Asian in origin. Common Carp, by the way, are believed to have originally come from the Caspian Sea. Back in the 1880’s the U.S. Commission of Fish and Fisheries intentionally distributed Common Carp in rail cars across much of the United States to serve as a food fish, but the idea never caught on as extensively as hoped due to the habit of wild carp to scavenge the bottom of water bodies.
Common Carp are invasive, but are considered naturalized. They can be deleterious to stream and lake bottoms, and do impact other fish, bird, and mollusk species as well as plants, but at this point the damage has been done, so to speak. After nearly 140 years native fish and other animals have adapted to Common Carp. Some fishermen and environmental agents prefer to kill Common Carp whenever they are caught, in many cases simply throwing them on the stream bank to suffocate, but in truth this has little if any effect on the population since their recruitment rate is extremely high.
Silver and Bighead Carp were brought to the United States during the 1970’s and 1980’s, and escaped into the Mississippi River watershed from their state, federal and privately run facilities following extensive rains that overflowed the hatcheries. In the Mississippi River and many tributaries they are securely established in abundances that impact native fish species and interfere with local trawling concerns.
Adult fish species that are known to be adversely affected by Silver and Bighead Carp are Gizzard Shad and Bigmouth Buffalo. The dietary overlap of the carp with these native fishes has been shown to reduce the adults’ size and health. In addition the high volume planktonic grazing employed by these carp is likely to compete for that food source with larvae and young-of-the-year of most other native fishes, ultimately causing a reduction in native populations.
Grass Carp are established in lakes and rivers across the State of Ohio. Deleterious effects from this invader include removal of macrophytes (large aquatic plants) from stream bottoms with concurrent increases in turbidity. The macrophytes provide cover and spawning habitat for many native organisms. The carp only digest about 1/2 of the plants they eat, so the large amounts of fecal matter cause algal blooms. The OSUM crew has caught several Grass Carp already, euthanizing and saving samples from them.
It is not known at this point what the remediation would consist of if Bighead or Silver Carp do invade the Muskingum River. Similar to many other invasive species it would be extremely difficult if not impossible to completely eradicate them from waterways like the Muskingum River that have connections to other rivers that contain the species. Short of completely damming the river (which carries its own set of ecological problems), or installing an electric barrier as has been done between the Illinois River and Lake Michigan, eradication would be short-lived. It may be that the best approach would be to simply utilize the pests as a food source as has been done in Kentucky and other states, since their flesh is much more palatable than that of common carp. If we catch any Bighead or Silver Carp (electroshocking works well for larger Silver Carp, while hoop netting is one of the best methods for Bigheads) they will be euthanized with samples taken for DNA analysis, but we really do hope that is not the case.
About the Author: Marc Kibbey is Associate Curator of the Fish Division at the Museum of Biological Diversity.