Terms of Reference

Review of proposed Okanagan Sockeye fry introduction to Skaha and Okanagan Lakes: history, uncertainties, and implications

Science Response Process - Pacific Region

May 2017
Nanaimo, BC

Chairperson: Lesley MacDougall

Context

The Columbia River Basin supports a Sockeye Salmon (Oncorhynchus nerka) aggregate that is composed of three Sockeye Salmon populations including: the Okanagan population from British Columbia (BC), Canada, the Wenatchee Lake population from Washington State, and a very small population from Redfish Lake in Idaho that is listed under the United States Endangered Species Act. On average, the Okanagan population accounts for greater than 80% of all Sockeye Salmon returning to the Columbia Basin. Historically, the Columbia River supported substantial US commercial, Treaty Tribal, non-treaty, and Canadian First Nations fisheries. Sockeye Salmon production drastically declined during the mid- to late-20th century resulting in sporadic openings of commercial fisheries after 1972, as well as significant reductions to First Nations fisheries for the next 35 years.

One or more ecotypes of Sockeye Salmon that either complete their entire life cycle in freshwater (i.e. kokanee Salmon) or fresh and marine waters (i.e. sea-run Sockeye Salmon), represent the most abundant limnetic fish species rearing in three of the Okanagan Valley’s largest lakes (Okanagan, Skaha and Osoyoos lakes). Introduced Lake Whitefish (Coregonus clupeaformis) and native Rainbow Trout (Oncorhynchus mykiss) also occupy offshore waters of these lakes in much smaller numbers. Although not identical, the pelagic fish communities and supporting food webs that characterize the open waters of Osoyoos, Skaha and Okanagan lakes are very similar (Northcote et al. 1972; Andrusak et al. 2002). All age classes of Sockeye Salmon, kokanee and Lake Whitefish occupying these lakes are principally zooplankton feeders. In contrast, young Rainbow Trout depend on small aquatic invertebrates and plankton for food as juveniles but become piscivorous, consuming smaller kokanee and/or Sockeye Salmon in offshore waters as larger, older age classes (Scott and Crossman 1973).

In British Columbia, a federal – provincial Introductions and Transfers Committee (ITC) reviews applications to introduce or transfer cultured aquatic species to assess risks for possible disease, ecological and genetic effects on native species and ecosystems, and to ensure that the licensing requirements of s. 56 of the Fishery (General) Regulations are met. When issuing a license, the ITC may also prescribe certain measures to minimize risks associated with transfer activities (e.g. egg disinfection, quarantine of stock). Specifically, the ITC can recommend the Minister issue a license if:

1. the release or transfer of the fish would be in keeping with the proper management and control of fisheries;
2. the fish do not have any disease or disease agent that may be harmful to the protection and conservation of fish; and
3. the release or transfer of the fish will not have an adverse effect on the stock size of fish or the genetic characteristics of fish or fish stocks.

In 2004, the Okanagan Nation Alliance (ONA) began introducing hatchery-origin Sockeye Salmon fry to rear in Skaha Lake, as part of a collaborative “Skaha Re-introduction Project”. The ONA has more than a decade of experience in hatchery propagation and Sockeye Salmon fry introductions (2004-present) through the Skaha Lake Sockeye Salmon re-introduction program; including the completion of a 3-year disease and ecological risk assessment in advance of the program’s initiation (2000-2002). The disease risk assessment focused on the likelihood of introducing new or extending the range of known pathogens and specifically identified five pathogens of concern relating to the re-introduction program. The broader ecological risk assessment considered potential impacts of newly introduced Sockeye Salmon fry on resident fish populations and other aquatic biota. Since then, observational data to assess both disease and other ecological impacts have been gathered on an ongoing basis by the ONA, and subjected to annual review by the three-party (ONA, Fisheries and Oceans Canada [DFO], Province of British Columbia, Forests, Lands and Natural Resource Operations [BC-FLNRO]) Canadian Okanagan Basin Technical Working Group (Alexander and Hyatt eds. 2015). The ONA has applied to release up to 750 000 Sockeye Salmon fry into Okanagan Lake in 2017, and have indicated that their hatchery facility has the capacity to rear 7 million fry, with maximum single-year introductions estimated at 3.5 million fry.

To provide a recommendation regarding whether or not to authorize the release application, the ITC requires science advice regarding the potential ecosystem disruption, pathogen transfer, or genetic interference impacts associated with the proposed release. In the spring of 2016, the ONA received DFO approval to initiate a "ceremonial introduction" of 10,000 Sockeye Salmon fry into Okanagan Lake, and the ONA is expected to submit annual applications to introduce variable but larger numbers of Sockeye Salmon fry (e.g. up to and potentially exceeding 750,000 fry within the next several years) for release into Okanagan Lake.

DFO Aquaculture Management Division has requested that DFO Science review the literature and results from the ongoing assessment of the Skaha Lake experimental re-introduction program, as well as other applicable sources of information, and provide advice regarding the potential impacts and uncertainties associated with variable scale re-introductions of Sockeye Salmon fry into Okanagan Lake. The assessment and advice arising from this Canadian Science Advisory Secretariat (CSAS) Science Response (SR) will be used to assist in arriving at a regulatory authorization decision. Annual authorizations would require verification of no major detectable impacts on Okanagan Lake food-webs or its resident fish.

Objectives

With respect to the proposed re-introduction of Sockeye Salmon fry into Okanagan Lake and the potential effects on other aquatic species, including the genetic and disease considerations of this introduction, and on the habitat carrying capacity for the Okanagan system, this Science Response will address the following objectives:

1. Evaluate the evidence that Sockeye Salmon have been a historic part of the Okanagan Lake ecosystem given the potential natural barrier posed by Okanagan Falls to upstream migration of anadromous salmon.
2. Assess the potential impacts to the structure and function of existing food webs or to detectable production outcomes for sensitive aquatic biota, including Okanagan Lake kokanee (Oncorynchus nerka) and Rainbow Trout (Oncorhynchus mykiss) resulting from either a single year introduction of 750,000 (spring 2017) or ongoing introductions of between 750,000 to 3.5 million Sockeye Salmon fry into Okanagan Lake.
3. Assess the potential that the proposed introduction of Sockeye Salmon fry into Okanagan Lake may introduce new pathogens to fish in this portion of the Okanagan basin given either a single year introduction of 750,000  (spring 2017) or ongoing introductions of between 750,000 to 3.5 million Sockeye Salmon fry into Okanagan Lake.
4. Assess the potential impacts, due to genetic introgression, of annual introductions of Sockeye Salmon fry into Okanagan Lake to the two resident kokanee ecotypes given either a single year introduction of 750,000 (spring 2017) or ongoing introductions of between 750,000 to 3.5 million  Sockeye Salmon fry into Okanagan Lake.

Expected publications

• CSAS Science Response
• CSAS Research Document

Participation

• DFO Science, Fisheries Management, Aquaculture Management Division, Policy
• Province of British Columbia
• Okanagan Nation Alliance

References

Alexander, C.A.D. and Hyatt K.D., eds. 2015. Peer Review Workshop for the Okanagan Sockeye Re-introduction Experiment. Final Draft. Workshop summary report to the Okanagan Nation Alliance. 101-3535 Old Okanagan Highway, Westbank, BC V4T 3L7. 125 p. DOI: 10.13140/RG.2.1.3069.6085

Rae, R. and H. Andrusak. 2006. Ten-year summary of the Okanagan lake Action Plan 1996-2005. Ministry of Environment, 2006. Victoria, BC 36 p.

Northcote, T.G., T.G. Halsey and S.J. MacDonald. 1972.  Fish as indicators of water quality in the Okanagan Basin lakes, British Columbia. Preliminary report (Canada/British Columbia Okanagan Basin Agreement). 22:ii+78p.

Scott, W.B. and E.J. Crossman. 1973. Freshwater fishes of Canada. Fisheries Research Board of Canada Bulletin. 184:966p.