Invasive Asian Carps in North America

<em>Abstract</em>.—Efforts are underway in the United States to promote the commercial harvest of silver carp <em>Hypophthalmichthys molitrix </em>and bighead carp <em>H. nobilis </em>as a means of controlling the populations of these invasive species. The major uses under consideration are food for people, pets, and zoo animals. Fish in general are a good source of protein, beneficial lipids, and nutritional elements. However, fish from contaminated waters can bioaccumulate toxic elements and persistent organic chemical pollutants to levels that limit consumption. It is important that levels of chemical contaminants and nutritional elements in bigheaded carp of the various regions of the United States be measured. In September of 2005, 30 bighead carp and 30 silver carp were collected from the Missouri River near Easley, Missouri, USA, a location midway between Kansas City and St. Louis. Whole-body composites and skinless, bony white-meat fillet composites were analyzed for polychlorinated biphenyls (PCB), organochlorine pesticides, 2,2’,4,4’-tetrabromodiphenyl ether (PBDE-47), dioxin equivalents, percent lipid, mercury, lead, cadmium, arsenic, selenium, and several other elements. The data showed that in both species of these fish, levels of total PCB, total DDT, total chlordane, PBDE-47, dioxin equivalents, lead, cadmium, arsenic, and selenium were below levels of concern for consumption by humans and domestic animals. The average mercury concentration of 0.070 µg/g wet weight (ww) in three 5-fish silver carp white-meat fillet composites of this study was within the state of Missouri’s “unlimited consumption by sensitive populations” category (<0.088 µg/g ww). The more conservative advisory of the National Fish and Wildlife Contamination Program of the U.S. Environmental Protection Agency (USEPA) recommends a limit of three fish meals per week of the Easley Missouri silver carp white-meat fillets. Mercury levels in the three 5-fish composites of bighead carp white-meat fillets averaged 0.21 µg/g ww, falling into the USEPA limit of one fish meal per week. In whole body composites, mercury levels averaged 0.04 µg/g ww in the silver carp and 0.10 µg/g ww in bighead carp, placing both mercury levels below the 0.12 µg/g ww limit set for domestic animal consumption. Calcium concentration, an important factor in formulation of animal feed, was 21 g/kg dry weight (dw) in the whole-body composites of the silver carp compared to 57 g/kg dw in the bighead carp.