JOINT CHINOOK TECHNICAL COMMITTEE

Joint Chinook Technical Committee. 1993 Annual Report. TCCHINOOK (94)-1. December 6, 1994.

This report contains the Chinook Technical Committee's (CTC) assessment of the chinook rebuilding program through 1993. Major conclusions of the assessment are:

Through 1993, only 50% of the escapement indicator stocks are rebuilding.

Declines in escapements have not been stopped for 8 of the 18 stocks classified as "Indeterminate" or "Not Rebuilding."

Harvest rates for all fisheries constrained by PSC ceilings have not been reduced to levels projected when the rebuilding program was established in 1984.

Observed survivals for recent years have been below long-term averages.

Under existing management regimes and depressed marine survival conditions, only one-third of the model stocks representing naturally spawning chinook stocks are projected to achieve their escapement goals by 1998.

Since the rebuilding program is scheduled for completion in 1995 for Southeast Alaska and Transboundary stocks and in 1998 for other stocks, options for completing the rebuilding program become more limited and potential management measures become more restrictive with each passing year.

Therefore, the CTC recommends that substantial reductions in total fishing mortality should be implemented, beginning in 1995. For example, a 50% reduction in fishing mortality rates for all fisheries from recent levels would rebuild additional major stocks, sustain stocks that have been rebuilding, and provide protection for stocks that have not responded positively to the rebuilding program. The level of harvest rate reduction examined does not represent a CTC recommendation. Rather, the actual reductions implemented would depend upon policy choices regarding the stocks to be rebuilt and the management objectives and constraints for particular fisheries.

The CTC, therefore, further recommends that the Parties explicitly state their objectives for the remaining years and:

i) identify the set of indicator stocks that are to be rebuilt by 1998; and

ii) establish management objectives and constraints (e.g., minimum catch levels for fisheries, target harvest rates, etc.) for individual fisheries.

After these policy determinations are made, the CTC can provide assistance in evaluating alternative means of accomplishing the rebuilding objectives of the Parties in the years remaining in the rebuilding program. Further delays in responding to reduced abundances would increase the potential for even more severe disruptions of future fisheries to successfully complete the rebuilding program.

Even with substantial reductions in fishing mortalities some stocks are not expected to rebuild by 1998. The highly variable status of stocks within geographic areas indicates that it will not be possible to rebuild all stocks by 1998 through management of mixed-stock ocean fisheries. The CTC recommends, therefore, additional stock-specific management or rehabilitation actions to achieve escapement goals for these stocks.

Key Points in the 1993 Annual Report

1) Catch in Ceiling Fisheries and Exploitation Rates in Nonceiling Fisheries (Chapter 1)

In 1993, catch in fisheries with catch ceilings established by the PSC were either within the +7.5% management range (SEAK and NCBC fisheries) or below the -7.5% range (WCVI troll and Strait of Georgia troll and sport). Through 1993, the cumulative deviations in each fishery under these ceilings are all within the 7.5% management range, if the 1992 and 1993 add-ons presented by Canada are accepted (Chapter 1). In nonceiling fisheries, harvest rates were generally consistent with obligations for passthrough (as estimated by applying the nonceiling index suggested by the CTC, 1991) except for the stocks in the North Puget Sound summer/fall stock group in the southern U.S. marine fisheries (Chapters 3). However, in terminal fisheries, harvest rates have increased relative to the base period in eight of 24 escapement indicator stocks (Chapter 5).

2) Rebuilding Status of Escapement Indicator Stocks (Chapter 2)

This year's assessment of escapement trends included 44 naturally spawning escapement indicator stocks following the addition of the Deschutes fall stock and the splitting of coastal Oregon into two stock aggregates. Further, procedures for categorizing the rebuilding status of the escapement indicator stocks were revised, and resulted in a reduced number of stocks assessed as Indeterminate. Stocks that were assessed as Indeterminate or Not Rebuilding were further examined to determine if the decline in escapements had been stopped. As of 1993, 50% of the 36 escapement indicator stocks with goals were assessed as being Above Goal or Rebuilding, 44% were assessed as Not Rebuilding, and 6% were assessed as Indeterminate. Further, for eight of the 18 stocks that were assessed as Not Rebuilding or Indeterminate, we have apparently not stopped the decline in spawning escapements. Comparing escapement assessments through 1993 with previous years indicates that we are not progressively achieving the spawning escapement goals of the indicator stocks. Rather, the assessments have been very similar for the past four years and slightly poorer than during 1987-1990. The above figure was based on the 1993 assessment methods, data, and escapement goals and only accounts for CTC re-categorization of Indeterminate stocks in 1993. Explanation of these changes (5 Indeterminate stocks changed to Rebuilding) is presented in Chapter 2. Among the eight indicator stocks without escapement goals, six stocks were assessed as having 1989-1993 average escapements above base level, one stock was assessed as having average escapements below base level, and one stock has not changed from the base level.

3) Exploitation Rate Indicator Stocks (Chapter 3)

Examination of coded-wire tag data for 35 exploitation rate indicator stocks indicated that:

a) Reductions in fishery indices did not meet the 1984 projected reduction in any of the four ceiling fisheries (SEAK troll, NCBC troll, WCVI troll, and GST troll and sport), and increased in three of four fisheries compared to 1992. The 1985 target harvest rate reduction used previously in the CTC Annual Reports was replaced by the time trend of harvest rate indices projected by the 1984 version of the CTC chinook model. The CTC replaced the 1985 target for the reasons detailed in Section 3.3.1 of this report. Across ceiling fisheries, the average harvest rate reduction, compared to the base period, was only 5% in 1993, compared to the longer term average (1985-1993) reduction of 18%. Fishery indices calculated for 1993 fisheries were -26% in SEAK troll, -23% in NCBC troll, -1% in WCVI troll, and +29% for GS troll and sport fisheries.

b) In 1993, ocean total mortality exploitation rates were reduced from the base period in 13 of 17 stocks for which this comparison is possible (median reduction 10%, range from -21% to +9%). Combined ocean and terminal fishery total exploitation rates were also reduced in 13 of 17 comparisons (median reduction 5%, range from -23% to +23%). However, incidental mortalities increased relative to the base period in 14 of these 17 comparisons (median increase 4%, range -1% to +14%).

c) The age 2-3 survival indices for broods contributing to fisheries in 1994 and 1995 indicate that survival rates will be well below the base period levels for all stock groups with the exception of the SEAK/TBR-I groups. The largest reductions are projected for the Lower GS Falls (-97%), Upper GS Summer/Falls (-92%), North PS Summer/Falls (-91%), and WCVI Falls (-90%).

4) Model Projections for Rebuilding and Abundance (Chapter 4)

The CTC chinook model was used to estimate expected changes in chinook abundance in fisheries, and to project the status of the rebuilding program in 1998 under two marine survival and two harvest reduction scenarios. Chinook abundance in fisheries is expected to decline from the 1994 level in three of the four ceiling fisheries. In the SEAK and NCBC troll, the abundance is expected to return to base period levels (approximately a 50% decline in abundance from recent levels); in the WCVI troll, abundance is expected to continue decreasing to approximately 34% below the base period level. In contrast, in GS fisheries, abundance is expected to recover to base period levels by 1995. The rebuilding status of chinook stocks predicted by the model in 1998 is highly dependant on the marine survival rates assumed and the management actions taken in fisheries. For example, if future marine survivals are assumed to equal those of the most recent five years and existing management regimes are maintained, only one-third of the model indicator stocks representing naturally spawning chinook stocks would be predicted to rebuild by 1998. Previous modeling assessments have frequently assumed that future marine survivals would equal the long-term average survival rate. However, in almost every indicator stock, the more recent survivals are substantially less than this long-term average.

5) Variability in Response of Stocks (Chapter 5)

The integrated assessment continues to demonstrate the highly variable response of stocks to the rebuilding program. In only one of the 13 stock groups identified, were the component stocks assessed as having the same escapement rebuilding status (NPS-Summer/Fall, all three stocks categorized as Not Rebuilding). In all other stock groups, the component stocks ranged in escapement assessment categories from Above Goal to Not Rebuilding.

6) Deviations from Assumptions of Rebuilding Program

The PSC catch ceilings were established in 1984 (see PSC 1991 for details) with the expectation that the initial reduction of harvest rates associated with imposition of the ceilings would be followed by further progressive harvest rate reductions as chinook abundance increased during the rebuilding program. The initial reduction was expected to occur as a result of setting the ceiling for each fishery at a reduced level relative to recent catches, assuming that:

a) cohort survival rates would remain equal to the average rate observed in the base period;

b) the harvest rates in non-ceiling fisheries would not increase from base period values and would actually be reduced by 25% in Canadian net fisheries; and

c) that management actions would not alter the ratio of incidental fishing mortalities to reported catch observed in the base period used in the model analyses.

Further, in years in which abundance precluded harvesting the full ceiling without an increase in the harvest rate, the CTC recommended that further restrictions (e.g., restricting the season length) be implemented to restrict harvest.

The CTC's assessment through 1993 indicates that many of the assumptions used in developing the PSC chinook rebuilding program have been violated. These violations include reductions in survival rates, an increased ratio of incidental to reported catch mortalities, and the possible increase in exploitation rates in non-ceiling fisheries affecting the wild stocks in the North Puget Sound Summer/Fall stock group. As a consequence, exploitation rate reductions required to rebuild naturally spawning chinook stocks have been under-estimated and the fishery exploitation rates have exceeded those projected by the 1984 model. Under these survival and incidental mortality conditions, and the limited time remaining to rebuild, the exploitation rate reductions currently required for rebuilding will be substantially greater than originally predicted.

Previous Recommendations

Unfortunately, many recommendations presented in previous CTC reports have not been addressed and continue to be appropriate. Given expected reductions in chinook abundance, the CTC recommends that the Parties:

a) Consider alternatives to fixed quotas for controlling harvest rates. The wide fluctuation observed in chinook abundance suggests that required reductions in harvest rates will not be achieved with fixed catch quotas. Alternatives include the use of catch levels linked to predictions of chinook abundance obtained from the chinook model and/or methods that can effectively control harvest rates through fishing effort limitations.

b) Reduce incidental fishing mortality or set allowable harvests based on total mortality. Reductions in stock exploitation rates for reported catch have been offset to a significant extent by increases in incidental mortality. Incidental mortality reductions would increase the number of chinook available for harvest and/or escapement.

c) Initiate stock-specific investigations to evaluate stocks assessed as Not Rebuilding and develop stock-specific actions that compliment harvest controls, including enhancement and the reduction of nonfishing related sources of mortality. The investigations may include evaluation of escapement goals, escapement monitoring programs, fisheries management, and non-fishing sources of mortality. The severely depressed status of some stocks and the lack of a positive response in escapements suggest that, to rebuild some stocks, management actions additional to the control of harvests in mixed stock ocean fisheries will be necessary.

To continue the development of chinook stock assessments and facilitate understanding of the factors affecting chinook production, the CTC continues to recommend the following (see CTC, 1992b):

i) Conduct research on factors affecting freshwater and marine survival of chinook stocks. Factors such as predation, El Nino events, habitat destruction, and enhancement practices can significantly affect chinook production and the rebuilding program. Examination of environmental factors may also improve our capacity to predict abundance of chinook.

ii) Provide data required by the CTC to complete the escapement and exploitation rate assessments, specifically:

a) Report estimated CWT recoveries to the PSMFC by July of the year following the fishery. In the past, the estimated recoveries for Puget Sound sport fisheries, tributary sport recoveries in the Columbia River, and escapement recoveries for most southern U.S stocks have not been available by July.

b) Collect and provide information on the age and sex composition of the spawning escapement. Age- and sex-specific escapement data are essential to evaluate brood production, stock productivity, and escapement goals. Age- specific data also improve the quality of the calibration of the CTC chinook model.

c) Tag representative exploitation rate indicator stocks at sufficient levels. The CTC is especially concerned about the lack of adequate representation of spring and summer stocks and the lack of an indicator stock (with escapement data) for the Harrison River stock.

d) Establish consistent and standardized recovery programs for CWT fish at hatcheries and on spawning grounds. Accurate estimates of escapement are essential for the Exploitation Rate Assessment.

e) Provide estimates of sublegal encounter rates in fisheries with size limits, and legal and sublegal encounter rates in chinook non-retention and net fisheries. The CTC has estimated that incidental fishing mortality is approximately 30-50% of the reported catch (CTC 1987). However, sampling programs to determine the magnitude and stock composition of the nonlanded catch mortality are virtually nonexistent.

f) Provide estimates of nonreported chinook catches by Canadian Native fisheries. The CTC is unable to fully evaluate impacts of these fisheries on chinook stocks and the rebuilding program until these data are provided.