Phydee John Heng and Dr. Richard O. Kellems, Plant and Animal Sciences

Common carp (Cyprinus carpio) were first introduced into Utah Lake in 1881 with large numbers being imported between 1881 and 1903. Common carp ages 2+ years have an estimated population of 5.9 million in Utah Lake . A risk assessment, based on four categories of effects (i.e., predation, competition, abundance, habitat destruction), ranked common carp as the nonnative species with the highest potential for conflict with June Sucker recovery .

Relevance of Project

The June sucker (Chasmistes lirous), one of the thirteen fish species native to Utah Lake, was added to the list of federally endangered species with critical habitat on April 30, 1986. By the time a June Sucker Recovery Plan (JSRIP) was approved on June 25, 1999, the wild population had declined to fewer than 300 individuals. Studies have identified the common carp as the primary cause of the ecological changes that have occurred in Utah Lake which threaten the recovery of the June Sucker . Studies worldwide have also confirmed the direct improvement of lake ecosystems in response to carp removal. In light of these facts, the JSRIP will implement a large scale removal of carp from Utah Lake through mechanical fishing techniques in order to reduce the population to manageable levels and allow the ecology of the lake to improve and provide a habitat for the other more desirable species.

Immediate improvements to the Lakes ecosystem are expected with the removal of the carp. Potential viable uses of the carp are currently being evaluated. These uses hopefully will offset most if not all the cost of removal. There is a problem associated with this plan. On May, 16 2006 a fish consumption advisory was issued after a limited number of carp in Utah Lake were found to contain more than twice the level of Polychlorinated biphenyl (PCBs) allowed by the Environmental Protection Agency (EPA). The threat of harmful PCBs has halted the development of carp product for human consumption, but other uses are still being explored and evaluated. My role in this project was to conduct analysis of the level of PCBs in common carp collected from Utah Lake.

PCBs, all of which are man-made, are among the most stable organic compounds known. PCBs are a class of 209 different compounds referred to as congeners. PCB congeners are chlorinated biphenyls with one to ten chlorines attached to a biphenyl nucleus. The chemical and physical properties of the individual congeners are largely determined by the number of chlorines and the positions of the substituted chlorines. As the degree of chlorine substitution increases, the aqueous solubility and vapor pressure of the specific congeners decrease.

Research Results

Fifteen carp were collected from Utah Lake to be analyzed for PCBs. The carp were physically modified to facilitate the protocol of analysis. Each fish was filleted and skinned. The waste parts, offal, were also analyzed. The fillet and offal portions were homogenized separately and divided into three composite groups. The PCB analysis was performed by gas chromatography and mass spectrometry. The analysis was performed by Geochemical and Environmental Research group using standard operating procedures 9810 and 0205 .

More than 150 PCBs were analyzed in the fish collected. To measure their health effects, the concentrations of all detected PCBs were totaled and compared to the EPA total PCB screening value [EPA 2000a]. The Carcinogenic screening values was exceeded for PCBs in both the fillet and offal carp samples analyzed from Utah Lake.

Total PCBs found the fillet composites (0.0478 mg/kg fish tissue) exceeded the cancer screening value (0.02 mg/kg) for PCBs. Total PCBs levels were also elevated in offal composites (0.139 mg/kg fish tissue) exceeding both the cancer (0.02 mg/kg) and non-cancer (0.08 mg/kg) screening values. Total PCB concentrations did not correlate with average fish weight or length.

The U.S. Food and Drug Administration (FDA) have set regulations for tolerable levels of PCBs in foods and animal feeds. The temporary tolerance level for PCBs in the edible portion of fish and shellfish is 2 ppm. None of the fillet composites analyzed for this report exceeded 2 ppm, the highest level for a fillet composite was 0.063 ppm. The FDA also allows for levels of PCBs in animal feed components of animal origin up to 2 ppm.

There was no detection of any non-ortho substituted PCBs in the fish collected. Five mono-ortho substituted PCBs were found in the carp in small volumes.

Carp from Utah Lake exceeded EPA screening values for total PCBs for both fillet and offal samples. Under the levels of PCB contamination allowed for by the FDA, the carp from Utah Lake are considered safe for use as animal feed. However, the toxicity levels of the PCBs identified as mono-ortho are not significant in the fillet portions the carp. Further investigations will need to be conducted to evaluate the safety of using carp for human consumption.

References

• Valdez, R. A. 2005. A feasibility study of mechanical control and use of common carp (Cyprinus carpio) on Utah Lake. Final Report to the June Sucker Recovery Implementation Program. SWCA Environmental Consultants, Albuquerque, New Mexico.
• Ibid.
• Schmitt, Christopher J., Zajicek, Jim L., Peterman, Paul H. National Contaminant Biomonitoring Program: Residues of Organochlorine Chemicals in U.S. Freshwater Fish. Archives of Environmental Contamination and Toxicology 1990; 19: 731-747.
• Ahlborg et al. 1994. Toxic equivalency factors for dioxin-like PCBs: Report on a WHO-ECEH and IPCS consultation, December 1993. Chemosphere, Vol. 28, No. 6, 1049-1067.
• US Environmental Protection Agency (1997) Method 1668: Toxic polychlorinated biphenyls by isotope dilution high resolution gas chromatography/high resolution mass spectrometry. Office of Science and Technology, 199
• FDA (2003). Food and Drug Administration Total Diet Study Summary of Residues Found Ordered by
  Pesticide Market Baskets 91-3—-01-4 June 2003.