DNA Ploidy Analysis of Grass and Black Carp- La Crosse Fish Health Center
Determination of Ploidy Status
Since 2013, the La Crosse Fish Health Center has been leading the DNA Ploidy Analysis of Grass and Black Carp program for the Nation after the science was clearly established, and the technology was transferred from the Departments of Interior’s research agency, U.S. Geological Survey Invasives Species Research Program.
When a Grass Carp or Black Carp is captured in the wild, eyeball or blood samples may be collected and sent to the Center for ploidy determination. The La Crosse Fish Health Center uses flow cytometry to determine the ploidy status of carp samples. A sterile, or triploid, fish has three copies of nuclear DNA, whereas a diploid, or naturally produced fish, has only two copies. Nuclei from a triploid fish contain more DNA than diploid nuclei because of the increased nuclear DNA content. A flow cytometer measures fluorescence from stained DNA and compares samples to a known standard.
Results are collected in the USGS Nonindigenous Aquatic Species Database which catalogs, assembles data, and can generate spatially referenced accounts of the invasive carp in maps. Knowledge of the ploidy status of wild-caught invasive carps can help focus control efforts where needed. All information is available to the public.
USGS Nonindigenous Aquatic Species DatabaseInvasive Carp in the United States
Management of invasive carp populations is one of the biggest conservation challenges facing the United States today. Assessing the reproductive potential of grass carp and black carp in the wild can help fisheries managers determine control methods for invasive carp species. Grass Carp and Black Carp can be important biological tools for managing closed water systems. Grass Carp are voracious herbivores and can be stocked in ponds or lakes to reduce unwanted vegetation that may clog boat motors or affect recreational activities. Black Carp feed on snails, which often carry parasites, and can be used in aquaculture to reduce parasitic infections in farm-raised fish. The problem arises when stocked fish escape into waters where they could reproduce and compete with native species or impact endangered freshwater mussel and snail populations.
Creation of Sterile Stocks
A solution to prevent stocking of reproductive Grass Carp and Black Carp into the wild is to create a sterilized carp for stocking purposes. Grass Carp producers create sterile stocks of both carp species by treating the eggs to produce a triploid fish. Triploid fish have extra copies of DNA in each cell, which causes errors in the reproductive process, thus fish are functionally sterile and cannot reproduce. Many states require that all stocked Grass Carp be triploid for stocking purposes. Since the mid-1980s the U.S. Fish and Wildlife Service's National Triploid Grass Carp Inspection and Certification Program has permitted and certified triploid shipments to states where non-reproductive triploid Grass Carp stocking is allowed. Black Carp are prohibited in most states, but some states permit stocking of triploids by fish farmers to control snail-borne parasites in fish production ponds.
Directions for Sample Collection
Please include the Ploidy Analysis Data Collection Form to your shipment.
Ploidy Analysis Data Collection Form
When sending black or grass carp samples to the La Crosse Fish Health Center, please include this filled out form with the needed data.
Relevant Publications
Contact our Ploidy Analysis Coordinator
Contact us if you are going to send samples or have any questions.