The “good news” and the “bad news” regarding the Black Carp (Mylopharyngodon piceus) is that it eats snails, lots of snails. At 4-years of age, this large, Chinese fish, also called the Snail Carp, eats 3 to 4 lbs. of the mollusks per day. For 15-20 years, fish farmers in the southeastern U.S. have depended on this large Cyprinid to control the intermediate, snail hosts of trematode parasites in commercial fish ponds. For instance, only five to ten Black Carp per acre will eliminate the snails that cause the “yellow grub” fish disease produced by the common, digenetic trematode, Clinostomum marginatum. To the delight of fish farmers, there are even reports of complete eradication of snails from ponds using Black Carp.
Introducing a fish species with a high efficiency in snail predation might sound good to a commercial fish farmer, but that same eating efficiency raises alarms for those charged with protecting the often imperiled, native snails and mussels of the South. In 2007, USFWS added this 70 lb, snail-eating machine to its list of “injurious fish” and prohibits its further importation into the U.S. and interstate transport under the Lacey Act. To find out whether the Black Carp holds promise for invasive apple snail control in natural systems or is itself an exotic menace to the environment, I contacted the man who literally wrote the book on the subject (see below), Dr. Leo Nico, Research Fisheries Biologist at the Florida Integrated Science Center in Gainesville, Florida.
Dr. Nico did not mince words, stating, “I consider use of Black Carp in the wild for snail control to be very misguided. There is much potential for harm to non-targeted native mussels and snails. Although triploid Black Carp are considered non-viable, these fish have a life span of 12 to 18 years, maybe more. So, even the sterile fish have the potential to cause harm over a relatively long period of time. Black carp also grow to a large size — commonly over 1 meter. Individuals over 2 meters long have been taken in rivers in China and Japan.” Now, that is a large fish!
Dr. Nico had other concerns, “Will there be problems with the certification of triplody? Will ponds containing the reproductive, diploid Black Carp be flooded allowing escape, as has occurred in the past? The food selectivity of the Black carp is largely unknown. Will they prefer native snails over the exotic apple snails? Will they consume other invertebrates, such as crawfish? They are very similar in appearance to the herbivorous Grass Carp (Ctenopharyngodon idella). Will Black Carp be misidentified as Grass Carp and unintentionally introduced into the wild?” Until those and other questions are answered, it is clear that the use of the Black Carp to control exotic apple snails in the wild is a bad idea – – a misguided missile. Posted by Jess Van Dyke
For more information, contact:
Leo G. Nico, Ph.D.
Research Fishery Biologist/Ichthyologist , U.S. Geological Survey
Black Carp (USFWS): http://www.fws.gov/blackcarp-b.pdf
This book is available at: http://www.afsbooks.org/x51032xm.html