Stock assessment - Pacific salmon
Stock assessment information is essential for managing fisheries in a sustainable manner.
The following types of information are crucial to the stock assessment process:
- Pre-season forecasts used in pre-season planning and stock status reports to identify longer-term trends in stock abundance, key conservation concerns and outlooks for the future.
- In-season stock assessment and re-forecasting of run sizes using information gained from test fisheries, catch monitoring programs and escapement surveys. In-season data provides information on run timing, stock composition, stock abundance, age structure and other information used to make in-season adjustments to management plans.
- Post-season evaluations (estimates of total run size, harvest rates, catches, fishing effort, escapement and other factors used to assess whether escapement goals and other management objectives have been met).
The Pacific Scientific Advice Review Committee (PSARC) is the regional body responsible for review and evaluation of scientific information on the status of living aquatic resources, their ecosystems and the biological aspects of stock management.
In B.C., the PSARC Salmon Sub-committee is the primary body providing pre-season scientific advice for the development of management plans for Pacific Salmon, and operates via an open and transparent peer review process. PSARC is comprised largely of Fisheries and Oceans scientists, with participation from Departmental fisheries managers, academics, First Nations, stakeholders, other government or private institutions and the general public.
Each year, the PSARC Salmon Sub-committee produces two types of scientific advice for the purposes of salmon planning. It provides advice on forecasts of returns to specific systems for the upcoming season as well as management advice based on more extensive scientific reviews of the status of selected salmon stocks. Summaries of these scientific reviews are also made available as Science Advisory Reports (SARs).
Pre-season forecasts of salmon returns are based on biological and/or statistically based models. Models vary between different stocks or stock groupings depending on the life history and production patterns of that stock and the data available. The variables typically used in the production of stock forecasts are historic trends in escapements and total returns, returns of sibling age classes, and returns and escapement of the brood (parental) year. There is a growing use of environmental conditions as a variable factored into forecasts.
In addition to forecast reports which present a short-term outlook for the upcoming season, SARs also focus on the long term trends in the status of populations, the current status, and science advice on the extent of conservation measures required to maintain the stock's viability for the future. SARs are plain language summaries of in-depth technical working papers on the status of various salmon stocks.
The PSARC Subcommittee meets to review science-based assessments in support of fisheries management . Conclusions and recommendations accepted by the group are publicly available in the form of detailed Research Documents, SARs and Proceedings Documents. Advice from PSARC meetings are also provided to senior management in regular updates to the Regional Management Committee.
PSARC Stock Status Reports now available on the Canadian Science Advisory Secretariat (CSAS) site.
SC STAD In-season Salmon Bulletins
South Coast Stock Assessment Division (SC STAD) has a selection of in-season project reports/bulletins and updates. These bulletins provide a summary on the assessment activities of the project and/or a general update on salmon related activities in the area. The bulletin series generally follows a pre-season bulletin outlining the project, with several in-season weekly bulletins, followed by a post season summary report. The bulletins are intended to provide a brief synopsis only. More technical or detailed information is available upon request post season.
As Pacific salmon begin returning to spawn each year, the Department engages in a process of in-season "re-forecasting", adjusting the pre-season run size forecasts based on actual observations of salmon abundance. These re-forecasts are conducted on a regular basis for various stocks using a variety of analytical models and information from several sources including catch rates in test fisheries and commercial fisheries, other harvest information and escapement surveys. Often, the ocean fisheries in which returns are first detected are on mixed stocks, and mechanisms to differentiate stocks must be in place. Techniques used include DNA analysis, scale analysis, coded wire tags (CWT) from hatchery-produced fish and other tagging programs.
Re-forecast information is typically updated on a weekly basis. As returns build, the reliability of this information increases, with greatest reliability achieved at or past the peak of the run. These weekly updates, many of which are available on the Internet, are key to in-season decision making both by managers and harvesters. Summary bulletins of weekly management decisions based on in-season stock assessments are also available.
Reliable catch monitoring is taking on increasing profile as a crucial piece of the stock assessment process.
There is a variety of catch monitoring programs in place for First Nations fisheries. Most major First Nations salmon fisheries including the Fraser River fisheries are monitored and sampled and regular reports are produced. Some First Nations fisheries that involve economic opportunity fisheries have mandatory landing programs. Other fisheries are monitored through catch and effort sampling programs and census data. The Department conducts some programs but most fisheries are monitored by First Nations' technical staff.
In the recreational sector, most major salmon tidal and non-tidal sport fisheries are monitored though creel surveys (interviews of sport fishermen at landing sites), vessel counts (via aircraft overflights), or logbook programs, with some of the fishing lodges and charter operators in Pacific Region. Creel surveys generally operate during peak fishing times only.
In the commercial sector, harvesters are now required to fill out logbooks of all catches and participate in various hail-in programs. In some cases, independent observers are a mandatory requirement to verify catch data to managers. Mandatory landing slips (official records of salmon sold), also provide catch information.
Coast-wide, Fisheries and Oceans Canada and its partners expend considerable effort to determine salmon escapements (the number of salmon that reach the spawning grounds after "escaping" the fisheries). Most escapement enumeration programs fall under the responsibility of the Stock Assessment Division of Fisheries and Oceans Canada. Work is done with a range of partners, including First Nations and local community organizations. Techniques used include counting fences, visual surveys and mark-recapture programs. Annual estimates of the on-the-grounds escapement are compiled for many stocks by Fisheries and Oceans Canada.
At the end of the salmon harvest and spawning season, actual escapement is compared with pre-season targets to evaluate the effectiveness of management measures. Escapement data are used in the development of subsequent years' forecasts and escapement goals and in tracking long-term trends in survival and productivity.
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