Report on Harvest Management of Columbia River Salmon and Steelhead

  • Full report (this report was re-posted June 30 to correct printing problems with Figures 3 and 5)
  • Technical issues on marking (document ISAB 2005-4a, summary of technical issues surrounding impacts of mass marking and mark-selecting fishing, in response to Council members' questions during the July ISAB presentation of this report)


The Independent Scientific Advisory Board (ISAB) produced this report at the request of the Northwest Power and Conservation Council, the Columbia River Inter-Tribal Fish Commission, and NOAA Fisheries. The ISAB reviewed the effects of harvest management on the sustainability of salmon and steelhead from the Columbia River Basin. Specifically, the ISAB investigated, and reports on the biological basis and management processes involved in providing and controlling harvest, how uncertainty in information and parameter estimates can be accounted for in decision making, and how harvest may be integrated with recovery objectives. The report also provides brief reviews of past management practices, current institutional structures for harvest management of Columbia River salmon, and background information on five topics related to salmon production and harvest management. For people less familiar with this topic, an introductory description of harvest management terminology and practices is included (Section 7e).

The ISAB was impressed with the management processes that have been developed and the continued efforts to expand the scientific basis for recovery of depressed populations. The elements of science, commitment, cooperation, and investment were all evident in harvest management planning; however, concerns about the conservation of naturally produced populations remain. The ISAB's vision of conservation and sustainable use is centered on decision processes that are necessary to ensure that the removal (i.e., total mortality from all sources) of Columbia River salmon does not exceed the productive capacities of naturally spawning populations over the long-term. From this perspective, effective harvest management systems must have three primary components:

1. Sound Scientific Foundation

A sound scientific basis for harvest management would: (1) provide the best practically obtainable and pertinent data; (2) provide the best available science at the time decisions are made; (3) appropriately account for uncertainty, and (4) ensure transparency for the basis of advice, analyses, competent peer review, and a process for regular review and response (learning) as experience is gained. Given the uncertainties and unknowns that remain in salmon management and recovery, a priority should be placed on ensuring a stronger empirical basis for assessing trends in each production unit (group of natural and hatchery salmon populations that are treated as a unit for harvest purposes), and on obtaining key information required to control harvest impacts.

2. Clearly Defined Management Objectives

Effective harvest management requires: (1) definition of the production units to be managed; (2) biological conservation targets for each production unit; and (3) objectives and priorities for fisheries and clearly defined risk tolerances. Recent identification of independent population units has made notable progress in characterizing the fishery base, but conservation targets are not as well defined and are often not fully integrated with harvest management capabilities. In spite of all of the data that have been collected on Pacific salmonids, the reality is that fisheries management is inexact. Risk can be minimized and future options preserved in a dynamic and unstable environment by maintaining a genetically diverse mix of component populations and their habitats. A scientifically sound decision process would protect a minimum spawning population size in each unit, given the current and potential future range of environmental conditions and the range of error in assessments.

3. Capacity to Constrain Total Fishing Mortality

With a multitude of institutions having regulatory authority over Columbia River fish, there would seem to be ample opportunity to constrain total fishing mortality through both regulations and enforcement. Unfortunately, the distribution of responsibility for achieving the biological conservation targets for individual production units is fraught with such controversy that the aggregate result is often less satisfactory than required.

While the ISAB has been favorably impressed with the development of biological science and management processes, three fundamental components of harvest management are noted as significant concerns. These include: (1) insufficient quantitative data for individual production units; (2) very limited evidence of stock assessment analyses for individual production units to track trends in status and provide a biological basis for harvest goals; and (3) little accounting for uncertainty in management plans, with the exception of reference to precaution in the National Standard Guidelines established under the Magnuson-Stevens Fishery Conservation and Management Act.

The ISAB makes four recommendations:

1. Core Monitoring Data

There is an essential need for a core set of quantitative data to be monitored annually in all production units or, at least, in a sub-sample of units that may be used as representative indicators of productivity and trends in abundance over time. With the obvious importance of defining recovery goals and monitoring progress to recovery, establishing quantitative indicators within Evolutionarily Significant Units (ESUs) is required for a credible harvest management system. We strongly caution against the collection of data without carefully thought-out design and evaluation.

2. Documented Assessments

The ISAB found very few quantitative analytical assessments of individual production units within ESUs. Such assessments typically provide the basis for harvest management planning. Detailed assessments should be peer-reviewed to provide quality assurance.

3. Accounting for Uncertainty

While many documents refer to uncertainty, there were very few examples of actually estimating uncertainty or accounting for it in management plans. Analysts often know much less about the production dynamics of Pacific salmonids than is assumed, and uncertainty is very likely to be much greater than appreciated. All sources of fishing mortality should be accounted for and a level of risk tolerance established through public consultation. While the ISAB was impressed with the intensive process used for salmon management, we also recommend analysts review whether current levels of harvest impact are consistent with the quality of data and level of uncertainty used in management processes, and would provide the expected likelihood of recovery for listed species.

4. Adaptive Management in Salmon Recovery

Given the limitations in historical data, the limited progress on recovery planning, the inherently large uncertainty, and the complexity of management processes involved in harvest management of Columbia River salmonids, the ISAB recommends application of adaptive management principles in salmon recovery. Although we acknowledge potential problems with implementing a truly adaptive program in such a complex environment, we believe that a systematic approach to testing alternative actions with an emphasis on achieving secure spawning escapement levels should be seriously considered. Such alternative actions may include stepped harvest rates weighted to protect minimum spawning levels, manipulations of hatchery production and/or the hydrosystem operations, and testing various incentives for recovery. The ISAB anticipates significant increases in understanding of climate and ocean changes in relation to salmon in the next few years, and significantly increasing uncertainty in the accuracy of production forecasts in the short to medium term. Fishery managers need to be in close touch with this understanding and adjust their procedures for setting allowable harvests.

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