August 07, 2002 11:57 AM
Introduction
The Fraser River is the largest producer of sockeye salmon in the world, and contributes the majority of the salmon harvest for both commercial and native fisheries. Approximately 100 different stocks of sockeye utilise the Fraser River, most of which spawn in the Upper Fraser River. Sockeye stocks utilizing the Upper Fraser River were decimated by the Hells Gate slide (1913) which blocked passage during their annual spawning migration. A cooperative venture between the United States and Canada resulted in the building of the fishway at Hells Gate, and sockeye stocks have been on the rise since. In return for the aid provided by the USA in building the fishway, Canada agreed to allocate an equal portion of the annual Fraser sockeye run to American fishers for waters managed by the Fraser River Panel, in an area called the convention waters (map 42k). This agreement was in place until 1985, after which the Pacific Salmon Treaty came into being, which led to a more beneficial sharing arrangement for Canada. In this process, the International Pacific Salmon Commission, later to become the Pacific Salmon Commission (PSC) was born providing a non-partisan means to aid managing the commercial harvests of Fraser River sockeye salmon by each nation.
For an excellent synopsis of this species please visit the Alaska Department of Fish and Game Homepage.
Stock Complexes
At present, the Department of Fisheries and Oceans (DFO-Canada) and the PSC manages harvests (commercial and native) of the various sockeye stocks entering the Fraser River (British Columbia) on the basis of stock complexes. There are four stock complexes presently identified in the harvest management system being used by the DFO, the PSC, and various fisheries managers, including: the Early Stuart Complex (map 27k), the Early Summer Complex (map 29k), the Summer Complex (map 29k), and the Late Complex (map 29k).
Aside from the Early Stuart Complex, each of the other complexes represent sockeye returning to a number of different streams that are spread over a wide geographic area within the Fraser Watershed. Even the Early Stuart Complex represents sockeye returning to a number of smaller streams which are tributaries of the Stuart River (there is actually very little sockeye spawning within the Stuart River mainstem). Aside from the similarity in migration timing, there is little in common between the various sockeye stocks which make up the larger complex.
Pre-Season Forecasts
The Department of Fisheries and Oceans (DFO) combined with the Pacific Salmon Commission (PSC), provide yearly preseason forecasts of the number of sockeye expected to return to the Fraser River. These forecasts are based upon a number of criteria, including the size of the spawning escapement of a particular stock of sockeye for the last cycle (cyclic dominance), as well as freshwater and ocean rearing conditions that occurred during the growth period for the specific sockeye stock cycle.
Migration Timing
Sockeye Salmon rear in the North Pacific Ocean for most of their pre-adult life. After having spent 2 to 3 years growing to adult size, sockeye salmon destined for the Fraser River begin their migration down the coast of Alaska and British Columbia towards the Fraser River. This migration begins in June and continues through to October. Although sockeye complexes are separated on the basis of their migration timing through the mouth of the Fraser River, a considerable amount of overlap exists between each complex, as demonstrated by the migration-abundance curve.
Test Fisheries
Pre-season forecasts are adjusted once each sockeye stock complex nears the Fraser River, through analysis of the results from a series of test fisheries managed by the PSC. Test fisheries re-occur in the same areas every year, using the same fishing techniques and the same boats which fish the same spot for similar periods every year. This long term test fishery information utilizes catch per unit effort data (CPUE), the number of fish caught per hour per net, to provide some indication of the return strength of sockeye stocks. Scale data sampled from sockeye captured in the test fisheries identifies the proportion of each stock complex which is contributing to the total test fishery catch. A number of test fisheries occur within pre-designated statistical areas within Canada and the US (map 51k). In this way test fisheries are used to aid in not only determining if a commercial fishing opening can occur, but also in managing the number of sockeye harvested from a particular stock complex during the ocean fisheries.
Mission Echo Sounding Station
After a sockeye complex enters the Fraser River, a facility at Mission British Columbia, called the Mission Echo Sounding Station, uses sonar to estimate the number of sockeye that have entered the Fraser River as they pass Mission. This facility consists of a boat which travels back and forth across the Fraser River over 200 times a day, making paper chart plots of fish that are sounded in the water as they pass under the sonar. Like test fisheries, counts at Mission are linked to scale data sampled from sockeye captured in the test fisheries just downstream of the echo sounding station. The scale data identifies which stock complex a captured sockeye is from, and the proportions of each complex represented in test fishery catch is applied to the Mission counts to provide an estimate of the number of sockeye belonging to a specific stock complex migrating past Mission. Information from the Mission Echo Sounding Station, although not fool-proof, is the most accurate information available to provide in-season estimates of escapement size prior to sockeye actually reaching the natal streams in which they spawn.
Unfortunately, only sockeye migrate in sufficient numbers to be discerned by the Mission Echo Sounding Station; therefore, the facility provides no information regarding migration numbers for other species (other than pink salmon during cycle years). See management information for in-season estimates from the Mission Echo Station.
Salmon Harvests
Salmon are exploited by commercial, recreational and native fisheries as they migrate inshore and upriver on their way to their natal spawning streams.
Commercial Harvest
Commercial fisheries originating from both Canada and the United States exploit salmon returning to the Fraser River. The proportion of the estimated forecast of sockeye salmon, as well as other species of salmon (chum, pink, chinook and coho), harvested by the commercial sectors of each country are determined through the Pacific Salmon Treaty, which is presently being negotiated between the United States and Canada. Commercial fisheries have continued, in the absence of a negotiated deal, for the past two years. The size of the commercial harvest of sockeye, pink, and chum is closely monitored by each nation, and reported to the Pacific Salmon Commission (PSC) which publishes harvest information weekly.
Native Harvests
As the sockeye migrate upstream through the Fraser River, they are further exploited by a number of native fisheries. The number of salmon taken by each native fishery is determined prior to the start of the fishing season through bi-lateral negotiations between individual Indian Bands and the DFO. Native harvests of salmon are monitored by either Native Organizations or the DFO, depending upon the area of the Fraser River being surveyed. Once fishing begins, weekly summaries of native harvests of salmon are submitted to the DFO every week, until the end of the fishing season.
Travel Time Up the Fraser River
These maps show, graphically, where the majority of a salmon run will be found after the complex has reached the mouth of the Fraser River. To determine where the bulk of the fish are located, simply see how many days it has been since the start of the run and then locate that day on the map.
Maps
Spawning Ground Escapements
Some of the individual stocks of sockeye grouped within a larger stock complex are counted as they migrate into their natal streams by the DFO, Native Groups and Non-profit Organisations for an estimate of the spawning ground escapement. These escapement estimates are derived through a number of survey techniques, providing an indication of the strength of sockeye returns for specific streams.