Joint Chinook Technical Committee. Review of Canadian Proposal for Terminal Area Exclusion of Chinook Catches from the All-Gear North and Central B.C. Catch Ceiling. TCCHINOOK (91)-2. February 7, 1991

This report on the Canadian paper on terminal exclusions has been prepared by the bilateral Chinook Technical Committee (CTC) in compliance with the 1990 Letter of Transmittal. In this report, we review the purpose and objectives of the terminal exclusion approach, summarize data needs for implementing the concept, and review the three terminal exclusions identified by the 1990 Letter of Transmittal. A full technical review is not possible at this time, given the short time permitted for review and the limits of available information. However, we conducted a preliminary constructive review of the data and analyses presented, and provide recommendations for further data or monitoring needs. During technical review of the Canadian terminal exclusion report, it became apparent that a difference exists between the U.S. and Canadian understandings of how base catch levels in terminal exclusion areas were to be handled in the all-gear north and central British Columbia (NBC) catch ceiling.

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¹ Review of 1989 and 1990 Terminal Area Exclusion of Chinook Catches from the Northern B.C. Catch Ceiling. Prepared by Canadian members of the Chinook Technical Committee, February 4, 1991.

Conclusions and Recommendations

The general concept of terminal exclusions for harvest of localized natural or hatchery stocks returning in surplus of spawning escapement goals is a sound management approach. However, available data indicate that the three exclusion areas defined in the Canadian paper do not completely satisfy conditions for an ideal terminal exclusion. Because the Canadian terminal exclusion report lacks complete data analysis and because insufficient time was available for a complete review, the CTC is unable, at this time, to recommend unconditional technical acceptance of any of the terminal exclusion areas in the Canadian paper.

General Recommendations

1. Some procedures used to monitor fisheries and to estimate catches and stock composition need further refining. The sampling rates for coded-wire-tags (CWT) should be increased wherever practical and the accuracy of hail catch by subarea evaluated.

2. If the terminal exclusion program is continued, annual reports should be provided until such time as the CTC determines that they are no longer necessary to address technical concerns.

3. U.S. members of the CTC recommend that Canada provide a time schedule for providing data necessary to evaluate terminal exclusions.

Recommendations Specific to Exclusion Areas

Skeena

Presuming continued sampling and that completion of analysis of biological sampling data affirms assumptions regarding stock composition and maturity, this revised exclusion area is consistent with conditions for terminal exclusion.

Bella Coola

1. The CTC notes concern for local natural stocks classified as Probably Not Rebuilding. Consequently, terminal exclusion should be carefully evaluated and monitored for impacts on this depressed stock complex.

2. Exclusion area impacts on depressed natural stocks could be reduced by restricting the exclusion fishery to the early season, large mesh, gillnet fishery.

Kitimat

1. On the basis of information contained in the Canadian report, the case for the Kitimat exclusion area is the weakest of the three exclusion proposals. Confidence in this proposal is reduced by: the relatively high incidence of non-local and immature fish, the large fishing area involved, the presence of local natural stocks classified as Probably Not Rebuilding, and lower quality of data.

2. The CTC cannot recommend support for the 1989 and 1990 terminal exclusion as presented in the Canadian report due to the concerns identified.

3. The exclusion area would be consistent with conditions for terminal exclusion if exclusions could be limited to mature chinook returning to enhanced stocks in Subarea 6-1 during June and July only. Further time/area restrictions may be of value in achieving this objective.

4. Time and area resolution of catch and biological sampling data from sport census programs in the Kitimat exclusion area should be improved and more thoroughly documented.

5. A base catch level for a redefined exclusion area could not be directly estimated. The CTC recommends that the most technically defensible approach for calculation of a base level would be to use data collected for the 1989 and 1990 seasons; such a procedure would be conservative in that it would likely overestimate the true catch within this area during the 1979-1982 base period used for other exclusion areas. While this approach would be of limited value when determining exclusions for the 1989 and 1990 seasons, it would establish a base level for consideration of future exclusions for the Kitimat area. A more conservative base level catch implies a larger base catch before any exclusion catch is allowed.

Summary

In order for terminal exclusion to work for a particular area, the area must have a largely pure catch of the target stock with little incidental harvest of non-local or immature stocks. Reporting of the catch must be "clean", such that fish caught in other areas are not landed in and reported from the terminal area. There must be some means of determining the stock composition of the catches from the exclusion area. And it must be possible to define a base period catch level for the area such that only catches exceeding this level are allowed for exclusion. All these requirements are technically feasible, but need to be demonstrated for any potential terminal exclusion area.

Given limits of practicality for fisheries regulation and catch/sampling programs, some "contamination" (i.e. harvest impact on non-mature or non-local stocks) is unavoidable. The impact of the catch of non-local or immature fish in the exclusion areas on the rebuilding of individual natural stocks can likely not be assessed, but are likely less than impacts imposed by other changes to the rebuilding program (i.e. ceiling changes, increased incidental mortalities, etc.). Changes in large mixed-stock fisheries are likely to have greater impacts on rebuilding than changes in harvest rates by terminal fisheries which target local, mature stocks exceeding their escapement goals. Evaluations of future terminal exclusions should focus on whether the objectives and conditions of the terminal exclusions are achieved.

In conducting the studies associated with the three terminal exclusion areas in NBC, Canada Department of Fisheries and Oceans (DFO) found that it was necessary to redefine slightly each of the three areas. For the Skeena River, the terminal exclusion area was reduced to define an area more easily monitored for catches uncontaminated with catches from nearby areas. In the Bella Coola terminal area, it was decided to close Subarea 8-13 since catch in that area was too small to adequately sample. The catch from the Kitimat area was shown to have a higher contribution from non-local and immature fish than the Skeena or Bella Coola area. To focus the harvest on mature chinook (>5lbs.) returning to the enhanced Kitimat stocks, Canada proposed to limit the exclusion area/period to Subarea 6-1 during June and July. This experience demonstrates the necessity for flexibility and refinement in defining terminal exclusion areas.

Under circumstances where increased terminal catches result from new enhancement activities, a hatchery addon concept could alternatively allow harvest of new enhanced production. However, the hatchery addon concept determines the catch from new enhancement production (minus a risk adjustment) taken in addition to the allowable catch ceiling. The addon approach would increase demands upon tagging and sampling programs throughout B.C. areas where enhanced fish are harvested. Under the terminal exclusion concept, enhanced stocks contribute to non-terminal fisheries and thus contribute to the rebuilding program by buffering (i.e. increased contributions of hatchery fish would reduce impacts on other stocks in mixed-stock fisheries operating under catch ceilings).

The catch excluded from each area depends upon the base catch level established. The base catch is the portion of the base period catches taken in the exclusion area adjusted for implementation of the NBC catch ceiling. Different base catch levels result from the use of different assumptions. A decision on an appropriate base catch for each exclusion area is not purely a technical matter. Alternative procedures are outlined in this review.