Columbia River Basin Fish Contaminant Survey

The U.S. Environmental Protection Agency (USEPA) and the Columbia River
Inter-tribal Fish Commission (CRITFC) and its member tribes (The Confederated
Tribes of the Warm Springs Reservation of Oregon, The Confederated Tribes and
Bands of the Yakama Nation, The Confederated Tribes of the Umatilla Indian
Reservation, The Nez Perce Tribe) have completed a preliminary survey of toxic
chemicals in fish from the Columbia River Basin. The samples were collected
from those portions of the Columbia River Basin affected by tribal fishing in
Washington, Oregon, and Idaho.

The survey was designed to answer the following questions:

1. Are fish from the Columbia River Basin contaminated with toxic chemicals?
2. Are there differences in chemical concentrations among fish species and
study sites within the basin and other locations throughout the United States?
3. Are there potential human health risks from consumption of contaminated
fish?

This survey provides data on those chemicals which are most likely to be
accumulated in fish tissue and therefore pose the greatest risks to people.
These are the chemicals for which regulatory strategies need to be defined to
eliminate or reduce these chemicals in our environment. These results of this
survey can be used to design future investigations of chemical sources and the
effects of these chemicals on the fishery resources in the basin.

The tribal fish consumption patterns defined the types of fish that were
collected including whole body and fillet fish tissue from resident and
anadromous species and a few egg samples from anadromous species. The
anadromous species were: fall and spring chinook salmon, steelhead trout,
smelt, and Pacific lamprey. The resident species were: rainbow trout, mountain
whitefish, white sturgeon, walleye, largescale sucker, and bridgelip sucker.
Two hundred eight fish samples were collected at 24 sites1 in the basin from
July 1996 through December 1997. The results of the fish contaminant survey
showed that of the 131 chemicals analyzed 92 were detected in fish tissue. The
concentrations of pesticides were higher in the resident species especially
mountain whitefish, white sturgeon, largescale sucker, and whole body walleye
than in the rainbow trout, walleye fillet samples than the anadromous fish
species. Of the anadromous fish species Pacific lamprey had higher levels of
PCBs. The high levels of organic chemicals in whole body walleye and Pacific
lamprey appeared to be associated with high amount of fat in these fish types
since PCBs and pesticides are readily absorbed by fats. Of the inorganic
chemicals measured in fish tissue, zinc was at the highest concentration in all
species tested. Zinc is a natural element which occurs at high levels in soils
and water. There was no consistent pattern in chemical concentrations across
locations.

The chemical concentrations in fish species measured in this survey were
compared with fish from other water bodies across the United States and to
other food types. The levels we observed in fish from the Columbia River Basin
were generally lower than levels reported in the literature from the early
1970s and similar to levels reported in the late 1980s to the present. We also
found numerous studies in the literature that documented the presence of toxic
chemicals in all types of food as well as fish.