Skeena River Sockeye Salmon

DFO Science Pacific Region Stock Status Report D6-10 (1999)

Background

Anadromous sockeye salmon (Oncorhynchus nerka) occur throughout the temperate North Pacific Ocean. They spawn in rivers and lakes from the southern Kuril Islands north to Kamchatka on the Asian coast, and from the Columbia River north to Alaska on the North American coast. Although sockeye salmon exhibit remarkable variation in life history, they typically emerge from nests in gravel as free-swimming fry in Figure 1. Map of the Skeena River showing principal the spring, spend one or two years rearing in a nursery lakes for sockeye salmon. freshwater nursery lake, and then migrate to the ocean where they spend another two or three years before Skeena sockeye salmon smolts migrate to sea in late returning to their natal stream to spawn and die. April through June, then move northward along the coast and offshore into the North Pacific Ocean. Most In Canada, the Skeena River is second only to the Fraser mature at age 4 or 5, although males (“jacks”) also River in its capacity to produce sockeye salmon. At least commonly mature at age 3. The maturing fish return 70 distinct spawning sites and 27 lakes are utilized by from offshore waters of the North Pacific Ocean through sockeye salmon within the Skeena watershed. These Southeast Alaska and enter the Skeena terminal fishing nursery lakes are distributed from the coast to the high areas from late June through mid-August (The run interior regions and vary widely in size and productivity typically peaks on July 23.) Spawning occurs from late (Fig. 1). The 500-square-km Babine-Nilkitkwa lake July to October, but timing differs among populations system is the largest natural lake in British Columbia largely as an adaptation to local water temperature and supports the largest single sockeye salmon regimes. population in Canada. The Babine population has accounted for 75-95 % of Skeena sockeye salmon Fisheries production, averaging more than 3.8 million adult fish annually since 1990. Fry recruitment is greatly First Nations enhanced by spawning channels in the Fulton River and Pinkut Creek, which typically account for more than Sockeye salmon are an important food for First 70 % of smolt production from the Babine-Nilkitkwa Nations and aboriginal fisheries have operated in lake system. the Skeena River for at least 5,000 years.

December 1999 Pacific Region Skeena River Sockeye Salmon

Members of three First Nations, in 17 aboriginal introduced in the 1950s and grew rapidly through communities harvest Skeena sockeye salmon: the the next two decades. As many as 350 seine Carrier-Sekani (Babine Lake area), Gitksan vessels have fished Skeena sockeye, Wet’suwet’en (middle and upper Skeena) and predominantly in the outside fishing areas. Tsimshian (lower Skeena and adjacent ocean Significant reductions in the gillnet and seine areas). Catches for food, social or ceremonial fleets have recently been achieved through the purposes have averaged 150,000 fish in recent Fisheries and Oceans Canada fleet restructuring years (Fig. 2). Since 1993, new opportunities have initiative. The Canadian commercial catch of also developed for First Nations to selectively Skeena sockeye salmon has generally increased harvest sockeye salmon considered surplus to since 1970 to a record high of 3.7 million fish in Skeena spawning requirements. First Nations 1996 (Fig. 2). However, fishing effort was selectively harvested 500,000 surplus fish in severely restricted in 1997 and 1998 because of 1996, but no surplus was available in 1997 and low sockeye salmon abundance.

1998. 3 0.6 Many Skeena sockeye salmon migrate homeward FIRST NATIONS 2 0.4 through Southeast Alaska and a significant proportion of the total run is harvested in Alaskan 1 0.2 gillnet and seine fisheries (Fig. 2). The Pacific 0 0.0 Salmon Treaty limits catch in Alaskan fisheries 3 0.6 RATE EXPLOITATION directed at Skeena sockeye salmon, but other ALASKA 2 0.4 interceptions occur as incidental harvests in Alaskan pink and chum salmon fisheries. 1 0.2

0 0.0 Recreational 5 1.0

SOCKEYE CATCH (in millions of fish) CANADIAN COMMERCIAL 4 0.8 Opportunities for sport fishing on surplus enhanced sockeye salmon in the Skeena River 3 0.6 have been provided in recent years. However, the

2 0.4 recreational fishery remains extremely limited, with catches estimated to be only a few thousand 1 0.2 fish.

0 0.0 1970 1980 1990 2000 Resource Status YEAR OF RETURN Figure 2. Trends in catches (bars) and exploitation rates The management of Skeena sockeye salmon (line) by fishery. involves a compromise between the dual objectives of maximizing catch from a single Commercial productive stock (enhanced Babine sockeye salmon) and maintaining production from a The commercial salmon fishery on Skeena diversity of less productive salmon populations. sockeye salmon began with the first cannery Accordingly, sockeye fisheries in Area 4 are operations in 1877. Sockeye salmon were managed to moderate harvest rates (42%) and harvested predominantly by gillnets in the Skeena timed to reduce the incidental catch of Skeena River until the 1930s when powered vessels coho and steelhead, as well as the earlier- moved out to ocean fishing areas. In recent times, migrating non-Babine sockeye. The aggregate 200 to 1,000 gillnet vessels have fished from the escapement goal for Skeena sockeye salmon is Skeena River mouth to outside fishing areas 70 900,000, but management has typically aimed to km distant, accounting for about 75% of the increase both escapement and exploitation rate harvest of Skeena sockeye. A seine fishery was when abundance is high.

2 Pacific Region Skeena River Sockeye Salmon

A daily fishery model is used to evaluate Skeena sockeye salmon abundance declined alternative management scenarios and to estimate dramatically in 1997 and 1998, as forecasted from run size in-season. The gillnet test fishery at Tyee observations of pre-spawning mortality and in the lower Skeena River provides daily record low smolt abundance associated with escapement indices that are calibrated against parasite infections in Babine Lake. reliable escapement counts at the Babine River fence. A comprehensive monitoring program on Spawning Escapements and Freshwater the fishing grounds provides in-season estimates Production of commercial catch and effort. In-season forecasts of total abundance based on these data Escapements to enhanced sites in Babine Lake have proven to be relatively accurate by the typically exceed spawning requirements such that second or third week of the fishery. on average, more than a third of the Babine fence count is surplus produced by the Babine Lake Abundance and Exploitation Rate Development Project. This occurs because the enhanced Fulton and Pinkut runs cannot be Skeena sockeye salmon abundance has increased harvested fully in mixed-stock fisheries without dramatically since 1970 because of enhancement over-harvesting less productive populations. In efforts at the Babine Lake Development Project contrast, escapements to the co-migrating, wild and favourable marine survival. Over the same Morrison River run remain below escapement period, exploitation rates in the Canadian objectives and pre-enhancement levels. Recent commercial fishery have actually declined escapements to other wild runs within Babine because of increasingly restrictive management Lake whose run timing is either earlier or later actions to protect less productive populations of than the enhanced Fulton and Pinkut runs are not steelhead, coho and chinook. In contrast, the statistically different from pre-enhancement exploitation rate in the Alaskan fishery has levels. increased steadily from an average of 3 or 4% in 300 the early 1970s to 17% in the 1990s. Total BLDP (enhanced) FRY 90 exploitation rate for the aggregate Skeena sockeye 76 96 81 8486 92 200 salmon run has averaged 65% since 1990, 79 82 85 88 77 9193 80 exceeding 70% only in 1992, 1996 and 1997 (Fig. 7172 75 89 73 78 94 70 83 3). In part, the higher exploitation rates in the 74 87 100 95 1990s reflect selective harvesting of enhanced 68 66 69

sockeye salmon in-river and in terminal ocean NUMBER OF FRY (millions) 67 areas. 0 10 1.0 200 92

TOTAL EXPLOITATION RATE EXPLOITATION TOTAL 79 ESCAPEMENT BABINE SMOLTS 8 TOTAL CATCH 0.8 84 150 81 80 96 77 85 71 72 6 0.6 100 90 76 82 86 91 75 88 62 78 6769 68 89 4 0.4 50 64 70 74 83 73 63 93 59 606566 94 61 95 2 0.2 NUMBER OF SMOLTS (millions) 0 1950 1960 1970 1980 1990 2000

NUMBER OF FISH (millions) BROOD YEAR 0 0.0 1970 1975 1980 1985 1990 1995 2000 Figure 4. Trends in fry recruitment from the Babine YEAR OF RETURN Lake Development Project (upper panel) and total Figure 3. Trends in escapement (solid bar), total catch Babine smolt abundance (lower panel). (open bar), and total exploitation rate (line).

3 Pacific Region Skeena River Sockeye Salmon

Smolt production from the main basin of Babine because of continuing efforts to harvest enhanced Lake has increased dramatically as a result of Babine sockeye salmon more selectively (Fig. 6). enhancement (Fig. 4). The enhanced Fulton and However, escapements were generally poor in Pinkut runs now account for about 90% of fry 1998 due to a combination of low marine survival recruitment to the main basin. Even so, the and excessive harvest of the early-timing runs. available data suggest fry recruitment is still Alaskan fisheries accounted for over half of the below levels required to yield maximum smolt total exploitation rate on Skeena sockeye salmon biomass and maximum adult returns. In contrast, in 1998 because the Canadian commercial fishery wild smolt production from Nilkitkwa Lake was greatly restricted. appears to have declined to less than a quarter of the level observed before enhanced returns were OTHER SKEENA LAKES 120 51 first exploited in 1970. 100 50 53 5758 80 52 65 91 92 95 8 56 96 60 93 54 59 64 68 63 66 67 61 82 85 97 40 72 88 illions) 92 55 70 8086 87 77 62 73 78 90 69 71 6 60 79 83 8994 98 84 77 81 91 20 74 80 88 84 75 76

ESCAPEMENT (thousands)ESCAPEMENT 4 75 89 86 BABINE LAKE 69 81 2500 67 90 2000 85 63 85 95 71 1500 8182 92 938378 87 93 96 2 8272 64 79 88 91 59 73 1000 61 77 84 90 94 97 65 62 79 58 59 6970 717375 83 89 53 7274 86 98 66 63 67 76 7068 62 80 61 76 500 54 57 65 78 50 66 68 60 52 56 RETURNS TO SKEENA (in m (in TO SKEENA RETURNS 64 74 0 60 0 50 100 150 200 250 NUMBER OF BABINE SMOLTS (millions) 51

Figure 5. Relationship between Babine smolt abundance (thousands)ESCAPEMENT 55 and subsequent adult returns to the Skeena River. 1940 1950 1960 1970 1980 1990 2000 YEAR Labels refer to brood year; dashed lines indicate poor adult returns expected from the 1994 and 1995 brood Figure 6. Trends in escapement in wild (upper panel) years. and enhanced (lower panel) populations.

Increased smolt production from the Babine- Recent analyses of limnological and spawning Nilkitkwa lake system has led to dramatic ground survey data for the Skeena lakes indicate increases in adult returns (Fig. 5). However, the that in most cases, escapements are much too low relationship between adult returns and smolt to fully utilize lake rearing habitat and maximize abundance is non-linear, perhaps reflecting smolt production. Minimum escapement goals or competition among smolts. Even so, increased “limit reference points” are now being defined adult production could be expected from for the non-enhanced Skeena populations to increased smolt production. The disparity ensure their conservation. between smolt-to-adult survival in even versus Outlook odd years noted by previous investigators is no longer evident. Skeena sockeye salmon abundance is likely to be a record low in 1999, based on low Babine smolt Spawning escapements to other sockeye salmon abundance observed in 1995 and 1996 (Fig. 5), populations in the Skeena watershed have been corroborated by the weak returns of sibling age increasing steadily since the 1980s, presumably

4 Pacific Region Skeena River Sockeye Salmon classes observed in 1998. The sibling forecast salmon spawning grounds and tabulation of model indicates only a 75% chance that adult escapements in the Skeena River and returns to the Skeena River will exceed 409,000 Department of Fisheries Statistical Area 4. fish and a 50% chance that returns will exceed Fish. Res. Board. Can. MS Rep. Ser. (Biol.), 578,000 fish. Fortunately, smolt production has Nanaimo, 882:1-7. now returned to average levels, and Skeena sockeye salmon returns are expected to improve Wood, C.C., D.T. Rutherford, and L. Jantz. 1999. in 2000 and return to average levels in 2001. Trends in abundance and pre-season 1999 stock size forecasts for major sockeye, pink, For More Information and chum salmon stocks in northern British Columbia.Canadian Stock Assessment Contact: Secretariat Research Document 99/126: 50 p. Chris C. Wood Fisheries and Oceans Canada Wood, C.C., D.T. Rutherford, D. Bailey, and M. Pacific Biological Station Jakubowski. 1998. Assessment of sockeye 3190 Hammond Bay Road salmon production in Babine Lake, British Nanaimo, B.C. V9R 5K6 Columbia with forecast for 1998. Can. Tech. TEL: (250) 756-7140 Rep. Fish. Aquat. Sci. 2241: 50 p. FAX: (250) 756-7053 EMAIL: [email protected] This report is available: Dave Peacock Fisheries and Oceans Canada 417 2nd Avenue West PSARC Secretariat Prince Rupert, B.C. Pacific Biological Station V8J 1G8 Nanaimo, BC V9R 5K6 TEL: (250) 627-3467 Phone: (250) 756-7208 FAX: (250) 627-3411 Fax: (250) 756-7209 EMAIL: [email protected] E-Mail: [email protected] Internet Address: (www.dfo-mpo.gc.ca/csas) References

Burgner, R.L. 1991. Life history of sockeye ISSN 1480-4913 (for English series) salmon (Oncorhynchus nerka). pp. 1-117 in ISSN 1480-4921 (for French series) C. Groot and L. Margolis (ed.) Pacific salmon life histories, University of British Columbia La version française est disponible à Press, Vancouver. l’adresse ci-dessus. Foerster, R.E. 1968. The sockeye salmon. Bulletin of the Fisheries Research Board of Canada 34:113p.

Shortreed, K.S., J.M.B. Hume, and C.C. Wood. 1997. Recommended escapements to Correct citation for this publication secondary sockeye nursery lakes in the Skeena River system. PSARC Working Paper S97-9: DFO, 1999. Skeena River Sockeye Salmon. DFO 48 p. Science Stock Status Report D6-10 (1999).

Smith, H.D., and J. Lucop. 1966. Catalogue of