|Photo of eyed Atlantic salmon eggs. Credit: USGS
An Informational Bulletin from the United States Fish and Wildlife Service, Northeast Region
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
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.
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
- 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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