Summary

Description

This study was conducted by U.S. Fish and Wildlife Service biologists during 1998 and 1999. Burbot liver was the tissue of choice for this study because chlorinated hydrocarbons, or organochlorine compounds, are lipophilic and burbot use the liver as their main somatic fat reserve Love 1980. In addition, burbot consume high on the aquatic food chain and, therefore, are subject to the effects of biomagnification. The objectives of this study were to: determine the concentrations of organochlorine compounds in burbot livers at four sample sites in Interior Alaska; determine the significance of these data by comparing organochlorine concentrations in burbot livers with regional data for organochlorines in burbot and concentrations shown to cause effects in fish; and determine if further investigation of organochlorine contamination in biota of interior Alaska is warranted. Organochlorines are a particularly onerous group of compounds because they are lipophilic, persistent in the environment, bioaccumulate and biomagnify, and are neuroactive agents Hoffman et al. 1995. Examples of organochlorine compounds are polychlorinated biphenyls PCBs, DDT and its degradation products DDE and DDD, variations and degradation products of chlordane, and chlorinated benzenes such as hexachlorobenzene HCB. With some exceptions, e.g., PCBs Loganathan and Kannan 1994, concentrations of organochlorines in biota are generally declining Schmitt et al. 1999 due to numerous prohibitions on their use and production. Burbot liver samples were collected from the Tanana River below Fairbanks, Kanuti National Wildlife Refuge at Bettles Koyukuk River, Tetlin National Wildlife Refuge Tanana River, and Yukon Flats National Wildlife Refuge at Beaver Yukon River. Twentynine burbot were collected. Liver samples were dissected using hexanecleaned stainless steel instruments at a Fish and Wildlife Service laboratory in Fairbanks. In general, there were greater contaminant concentrations from the site below Fairbanks and Yukon Flats than from Tetlin and Kanuti. Analysis of the data was complicated by differing lipid concentrations in samples, differing fish weights among sites, and by a low sample size at Yukon Flats. Lipid concentrations of samples from Fairbanks and Yukon Flats were significantly greater than those of samples from Kanuti F3,25 8.5, P 0.001. There were greater concentrations of DDT and its metabolites at Fairbanks than at other sites, probably reflecting historical use of that pesticide within the city of Fairbanks and at nearby military bases. Concentrations of 3DDT from Fairbanks are up to two orders of magnitude greater than from five of six studies in Canada. The range of 3PCB concentrations from our study are similar to those from four of six Canadian studies cited and were generally less than laboratoryderived effects values. Toxaphene concentrations from our study were generally low. Further studies would help illuminate whether the concentrations we found at Fairbanks and Yukon Flats are of concern to fish and wildlife resources.