Montana Fish, Wildlife & Parks resumed stocking fish raised in the state trout hatchery in Lewistown after tests revealed PCB traces within the state’s one-meal per week consumption guidelines.
"We’re pleased to report that fish from several raceways that we tested for PCBs were within Montana’s one-meal per week guideline," said Chris Hunter, FWP’s chief of Fisheries in Helena. "Based on all we know, we’re confident that stocking these fish will not pose a risk to human health."
FWP recently tested samples of more than 300 fish from four Big Springs hatchery raceways containing about 80,000 trout. Composite results ranged from .018 to .048 parts per million in the four raceways from which fish will be stocked into Montana waters.
PCBs levels at or below .10 ppm pose a minimal risk to human health, according to the Montana Department of Public Health and Human Services. State public health guidlines suggest anglers and others could safely consume about one meal per week of fish with PCB levels up to .10 ppm, and one meal a month for fish with PCB levels between .11 and .47 ppm. "Do not eat" advisories are established for fish containing PCB concentrations above .47 ppm.
Big Spring hatchery fish from an additional five raceways showed higher PCB levels ranging from .08 to .24 ppm. Fish from the raceways will be retested and if the higher PCB levels are confirmed the fish will likely be destroyed.
Big Springs Trout Hatchery mostly stocks still-growing three- to four-inch long young-of-the-year fingerlings and eight inch-long yearling fish, which continue to grow after they are stocked. Hunter said the trace PCB concentrations will be further reduced as the fish grow to a catachable size.
Hunter said FWP will consider stocking fish raised at the Big Springs hatchery if they test within the state’s one-meal per week consumption guideline of .02 ppm to .10 ppm for PCBs in fish. Based on that guideline FWP began stocking about 80,000 rainbow trout Monday into Canyon Ferry Reservoir.
Hunter said FWP will discuss the possibility of stocking some fingerlings that slightly exceed the one-meal per week PCB threshold, but only if officials are confident the concentration will diminish to low-risk levels by the time the fish reach a catchable size.
Because testing every hatchery fish would be impossible, Hunter said the agency worked to gather enough fish from each raceway to obtain a statistically accurate measure of PCB concentrations in all fish in each raceway.
FWP also recently sampled 12- to 13-inch long rainbow trout in Big Casino Reservoir near Lewistown. The fish were raised at Big Springs Trout Hatchery and stocked last year when they were eight inches long. Those fish showed traces of PCBs, but in concentrations below laboratory calibration levels.
"It was a spot test, but it does appear to confirm that the PCB levels in these Big Spring hatchery fish were very low to begin with or that the levels diminished as the fish grew," Hunter said. "In either case, the fish are healthy and are providing anglers with good outdoor recreation."
In related PCB investigations at FWP’s Bluewater Hatchery near Bridger six- to eight inch long rainbow trout and grayling tested at less than .034 ppm, or below laboratory calibration levels. Wild brown trout samples gathered below the hatchery from Bluewater Creek, and six- to eight-inch long largemouth bass at the Miles City Warm Water Hatchery, also tested below laboratory calibration levels.
Last summer, the state Department of Environmental Quality discovered elevated levels of PCBs in Big Springs Creek sediments immediately downstream of the Big Springs Trout Hatchery. Subsequent FWP investigations suggest that paint used more than 25 years ago on some hatchery raceways is a source of PCBs in Big Springs Creek and in the stream’s wild trout.
Follow-up fish samples gathered from the hatchery in May detected elevated levels of polychlorinated biphenyls—PCBs—in some of the fish. As a result, nearly 500,000 fish were destroyed and stocking was halted.
Big Springs Trout Hatchery annually stocks about 1.25 million rainbow trout, 40,000 grayling and a total of 600,000 cutthroat trout, brown trout and kokanee salmon. It is the state’s largest production hatchery responsible for about half of the total weight of the state’s coldwater fish-stocking regimen, with the state’s other eight hatcheries responsible for the remaining half. About 25 percent of the hatchery’s fish are destined for stocking in Canyon Ferry, Holter and Hauser reservoirs near Helena. In all, about 100 different waters are planted with fish raised at the Big Springs hatchery.
PCBs are chemicals widely used through most of the 1970s as ingredients in a number of industrial materials, such as electric coolants; sealing and caulking compounds; and ink and paint additives. By 1977, concern about the impact of PCBs on human health and the environment led to a North American ban on manufacturing and importing PCBs. Excessive exposure to PCBs may cause a wide variety of adverse health effects, including cancer
Small amounts of PCBs are found in the environment all over the world. Traces of PCBs are found in our food as well as in our bodies. The body fat of animals and fish for example, can contain PCBs. PCBs do not occur naturally in the environment, yet are among the main chemical contaminants found in sport fish in several areas of the country, including the Atlantic and Pacific oceans.
Recent News
