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Review of Potential Impacts of Atlantic Salmon Culture on other Salmon Evolutionarily Significant Units

by the Fish Site Editor
11 August 2004, at 1:00am

By the National Marine Fisheries Service - This document examines the potential of Atlantic salmon farming in Puget Sound to impose adverse impacts on the Puget Sound chinook salmon (Oncorhynchus tshawytscha) and Hood Canal summer-run chum salmon (O. keta) evolutionarily significant units (ESUs), both of which were listed as threatened under the federal Endangered Species Act (ESA) by the National Marine Fisheries Service (NMFS) in March 1999.

Review of Potential Impacts of Atlantic Salmon Culture on other Salmon Evolutionarily Significant Units - By the National Marine Fisheries Service - This document examines the potential of Atlantic salmon farming in Puget Sound to impose adverse impacts on the Puget Sound chinook salmon (Oncorhynchus tshawytscha) and Hood Canal summer-run chum salmon (O. keta) evolutionarily significant units (ESUs), both of which were listed as threatened under the federal Endangered Species Act (ESA) by the National Marine Fisheries Service (NMFS) in March 1999.

Executive Summary

The threatened status of these populations requires that all activities that may harm the fish or their critical habitat be limited such that they do not appreciably reduce the likelihood for recovery of the ESUs in the wild.

Many of the activities that may lead to the take of listed salmon in Puget Sound, including the artificial propagation of salmonids in hatcheries and marine enclosures, will have effects that are incidental to otherwise lawful activities. Among such activities is the private culture of Atlantic salmon. This document presents the best scientific and commercial information available to evaluate the possible effects of salmon farming on listed chinook and summer-run chum salmon populations, and will provide the scientific basis for federal regulatory agency direction for the appropriate management of the industry in Puget Sound.

Much of the available scientific information pertaining to salmon aquaculture was produced by NMFS in furtherance of its national mandate to advocate environmentally sustainable aquaculture through research, technology development, financial assistance, and regulatory programs. Locally, Washington State policies also recognize aquaculture as a legitimate and beneficial use of its coastal waters. By reason of NMFS concomitant responsibilities to conserve Pacific salmon species, especially those listed under the ESA, the agency has also collected, analyzed, and published a significant amount of scientific information relevant to the specific issue of Atlantic salmon impacts on federally listed Pacific salmon. After conducting several scientific reviews of Washingtons Atlantic salmon farming industry, including the present one, NMFS concluded that the operations can be managed to minimize risks to local salmon populations. In particular, NMFS found that Washington State regulation of the industry provides adequate protection to stocks of Pacific salmon listed under the ESA. Nonetheless, there are legitimate issues associated with hatchery-reared salmon and trout that end up in natural ecosystems, either by deliberate release or by escape from the rearing facility.

Concerns regarding the artificial propagation of salmon and trout in the Pacific Northwest have been expressed numerous times in recent years, focused primarily on Pacific salmon hatcheries. However, concerns about the potential adverse impacts of private trout and Atlantic salmon culture in Washington have been expressed as well. Uncertainty about genetic and ecological interactions and the transmission of disease among Atlantic and Pacific salmon are the most commonly voiced concerns.

It should be understood that this review does not intend to evaluate potential risks associated with Atlantic salmon farming anywhere in the world except Puget Sound, Washington. Also, social issues related to salmon farming in Puget Sound are not discussed. Much of the material presented here has been taken from previous NMFS evaluations of the risks of Atlantic salmon in Pacific coast states or from NMFS ESA-related status reviews of West Coast salmonids.

The conclusions regarding the potential impacts of Atlantic salmon culture on the Puget Sound chinook salmon and Hood Canal summer-run chum salmon ESUs are based on three important assumptions. The first assumption is that the salmon farming industry in Puget Sound remains approximately the same size as currently or in the recent past. A significant expansion of the industry may increase risks and would require a reconsideration of some of the potential impacts discussed in this review. The second assumption is that salmon farms in Puget Sound continue to rear only Atlantic salmon. Should the local industry shift production to coho or chinook salmon or to steelhead (O. mykiss), the risks for hybridization, dilution of the gene pool, colonization, and competition for natural resources with wild salmonids will be greater than they are now with Atlantic salmon culture. Third, these conclusions assume that Atlantic salmon farmers in Washington continue to use only stocks presently in culture and that no new Atlantic salmon stocks are brought into the State.

Based on these assumptions, this review arrives at the following risk assessment conclusions: It finds no risk for one parameter, low risk for several parameters, little risk for other parameters, and no parameters for which the potential impacts from Atlantic salmon farms in Puget Sound are considered to be serious or even moderate.

The review finds no risk of adverse genetic interaction from transgenic salmon because there are currently no transgenic salmon being commercially cultured in Washington and there are no plans to do.

For several parameters, the risks associated with escaped Atlantic salmon are low, in particular:

  • The expectation that Atlantic salmon will increase current disease incidence in wild and hatchery salmon is low.

  • The risk that escaped Atlantic salmon will compete with wild salmon for food or habitat is low, considering their well-known inability to succeed away from their historic range.

  • The risk that salmon farms will adversely impact Essential Fish Habitat is low, especially when compared to other commonly accepted activities that also occur in nearshore marine environments.

For other parameters, there appears to be little risk associated with escaped Atlantic salmon, in particular:

  • There is little risk that escaped Atlantic salmon will hybridize with Pacific salmon.

  • There is little risk that Atlantic salmon will colonize habitats in the Puget Sound chinook salmon and Hood Canal summer-run chum salmon ESUs.

  • There is little risk that escaped Atlantic salmon will prey on Pacific salmon.

  • There is little risk that existing stocks of Atlantic salmon will be a vector for the introduction of an exotic pathogen into Washington State.

  • There is little risk that the development of antibiotic-resistant bacteria in net-pen salmon farms or Atlantic salmon freshwater hatcheries will impact native salmonids, as similar antibiotic resistance often observed in Pacific salmon hatcheries has not been shown to have a negative impact on wild salmon.

Introduction

In response to the depleted status of naturally produced chinook salmon (Oncorhynchus tshawytscha) and certain summer-run chum salmon (O. keta) in the Puget Sound region of Washington State, the National Marine Fisheries Service (NMFS) listed the populations as threatened under the U.S. Endangered Species Act (ESA) of 1973 in March 1999.

The populations or evolutionarily significant units (ESUs) (Waples 1991) listed for protection under the provisions of the Act were the Puget Sound chinook salmon ESU and the Hood Canal summer-run chum salmon ESU. Subsequent to these listings, NMFS designated critical habitat necessary for the recovery of the populations to healthy levels.

The Puget Sound chinook salmon ESUs critical habitat generally includes all freshwater areas accessible to anadromous salmon in the Puget Sound region, as well as the marine waters of Puget Sound. Critical habitat for the Hood Canal summer-run chum salmon ESU is encompassed within the area designated for chinook salmon.

Additional Information

To read the full report, please click here (PDF)

Source: National Marine Fisheries Service - June 2002

the Fish Site Editor

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