Photo of eyed Atlantic salmon eggs. Credit: USGS

Contaminant Loads in Broodstock Fish in the Region 5 National Fish Hatchery System

An Informational Bulletin from the United States Fish and Wildlife Service, Northeast Region
May, 2004

Background

A January 4, 2004 report in Science, and the media releases associated with the report, raised consumer safety concerns regarding farm-raised salmon and in fish consumption in general. The report documented elevated contaminant concentrations, including polychlorinated biphenyls (PCBs) and dioxins, in farm-raised salmon, and cited the likely source for the contaminants as the fish oil used in the commercial feed manufacturing process which the salmon subsequently bioaccumulate. While there are many regional and temporal differences in the feed manufacturing process, it is reasonable to assume that the exposure to contaminants by domestic broodstock within the U.S. Fish and Wildlife Service’s (Service) National Fish Hatchery System (NFH) is comparable to that of commercially raised fish in the general region, as feed suppliers are often the same. While a plan for monitoring the contaminant load in the Service’s Region 5 broodstock and feed sources is being developed, there remained a concern about body burdens in our existing surplus broodstock. Region 5 fisheries program administrators decided to evaluate whether these broodstock contain levels of PCBs, dioxins, and/or heavy metals that exceeded existing Federal consumption advisory safety limits. The concern was borne from the fact that surplus broodstock from the Service’s hatcheries are released to various States for stocking for recreational fisheries, and subsequently may be consumed by people.

Prior to the normally scheduled release of surplus broodstock in spring of 2004, the Service notified the eligible receiving States about the issue with possible contamination of the fish and informed them of the initiation of the contaminants survey. The Service provided reference to consumption advisories for recreational-caught fish developed by the U.S. Environmental Protection Agency (EPA) and further asked that the States notify the angling public of the possible contamination issue with the Federally-supplied fish. Actual transfer of the fish was halted prior to the Service receiving and evaluating the results of the contaminants survey.

Controversy exists in the scientific community over the ramifications of the conclusions presented by Hites et al. (2004). Specifically, while the levels of contaminants in farmraised salmon was 5-12 times higher than those found in wild salmon, the significance of those elevated levels, in terms of human health and safety, is debated among many scientists. While the reported overall average of PCB concentration in the farm-raised fish was well within the U.S. Food and Drug Administration (FDA) regulatory limits (2 ppm), these action levels are directed toward health risks associated with contaminant levels in commercial foodstuffs. The U.S. Environmental Protection Agency (EPA) uses a more rigorous risk-based approach for triggering fish consumption advisories in recreationally-caught fish. The EPA endpoints for selected contaminants result in more conservative guidelines when compared to FDA.

Objectives

The contaminant loads in adult broodstock within the Region 5 NFH system which are or could be destined for release into the wild were evaluated. This includes Atlantic salmon domestic broodstock from Nashua NFH and White River NFH, lake trout from Allegheny NFH, and rainbow trout from White Sulphur Springs NFH. Additionally, Atlantic salmon smolts from Green Lake NFH and Atlantic salmon sea-run adults returning to the Merrimack River (most of which are released as smolts, reared at Green Lake NFH) were evaluated. Specifically, the objectives were to assess contaminant loads of organochlorines and mercury in these broodstock. Target analytes included:

• PCB congener-specific scan,
• full scan for dioxins and furan (PCDD/F),
• lipid content, and
• total mercury
• dieldrin and endrin
• toxaphene
• numerous other organochlorines.

To Download the Bulletin

To read the entire Bulletin, complete with results and tables, please click the following link: contaminants_broodstock_fish.pdf (347 KB)

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