Harvest management of Columbia River salmon stocks involves five states, 24 Indian tribes, and two countries. These management efforts address allocation of harvestable fish among different fisheries and conservation of fish for rebuilding populations. By themselves, reductions in harvest of Columbia River Basin salmon stocks impacted by severely reduced freshwater survival have not been successful. Many stocks are projected to continue to decline in the absence of all harvest. Nevertheless, improving harvest management to account for differences in stock productivity is necessary to the rebuilding of salmon stocks.
Salmon and steelhead fisheries operate on a mixture of stocks, some of which are inherently more productive than others. These stocks differ in their geographic distribution and may be either hatchery-produced or naturally spawning. Harvest management ideally should be scaled to the productivity of stocks comprising a fishery. When productivity is known, fisheries can be structured to allow catch while meeting target escapement levels. When fisheries operate on aggregates of stocks having different levels of productivity, the lack of real-time, stock-specific information may result in higher than expected exploitation of weaker stocks (Larkin 1977; Whitcomb 1985).
Managers are faced with two objectives in mixed-stock fisheries: meeting escapement goals for each stock and documenting the effects of harvest management at the stock level. Both of these management objectives presume that managers can identify discrete stocks. Thus, it is essential as a first step that stock identification methods be devised that can discriminate stock components at the level of resolution chosen for restoration.
Fishery managers can incorporate analytical tools that provide stock-specific information to address stock-specific concerns to establish harvest rates that are consistent both with escapement objectives and with treaty rights to take fish at all usual and accustomed places. With appropriate levels of information, fisheries can be regulated to attempt to limit impact on less productive stocks.
- Develop assessment methodology for identifying individual stocks in order to track population dynamics. This requires stock-specific data on catch, escapement, age composition, and phenotypic and genetic traits. Population dynamics information will help relate fluctuations in productivity with environmental and induced effects on populations.
- Establish and monitor escapement checkpoints at mainstem dams and in index subbasins. Retrofitting of existing structures will be necessary. Monitor catches of salmon, lamprey, and sturgeon for stock composition. Methods to be used include video counting at hydropower dams and at key locations in tributaries, coded-wire-tags, scale pattern analysis, and genetic monitoring for heterozygosity. The least intrusive methods should be used to collect the necessary information. Make this information available through StreamNet.
- Establish additional monitoring programs for each of the subbasin tributary systems to monitor adult escapement and resulting smolt production, and to evaluate (by measuring the number of adults returning) the ability of managers to meet goals set by the Columbia River Fish Management Plan (CRFMP).
- Adapt current analytical models or develop new models to assess information on a more detailed stock-by-stock basis as the information is collected. Update the provisions of the PST and the CRFMP based on the latest information on survival rates and catch levels. Modify escapement objectives and harvest rate schedules as appropriate.
By establishing improved monitoring programs, stocks can be tracked throughout the life cycle, and problem areas can be identified. Better information will increase the accuracy of projections of future run status and enable managers to establish more responsive harvest regulations. Information can be used to project the harvest regulations needed to ensure escapement goals for weak stocks.
Expand existing efforts of tribal and state fishery agencies and fund the increased effort under the NPPC Fish and Wildlife Program, Pacific Salmon Treaty, and other applicable programs.