Joint Chinook Technical Committee. 1989 Annual Report. TCCHINOOK (90)-3. November 9, 1990

Executive Summary

1989 Chinook Salmon Catches in Fisheries with Ceilings

Estimates of 1989 catch for each fishery managed under a harvest ceiling established by the Pacific Salmon Commission are presented below. Catches are compiled from information available as of October 1990 (numbers in thousands).

The positive deviation for the catch in the North/Central B.C. fishery exceeds the 7.5% management range about the catch ceiling established by the Pacific Salmon Commission.

Cumulative Deviations from Catch Ceilings

Catches and cumulative deviations from catch ceilings since 1987, are as follows (number in thousands):

Escapement Assessment

Results from the Escapement Assessment indicate that the status of many stocks has deteriorated since 1988. The overall outlook for stock rebuilding in the 1989 escapement assessment is worse than in 1988. In 1989, 11 stocks were classified as either Probably Not Rebuilding or Not Rebuilding, compared to 4 in 1988. Furthermore, 16 stocks decreased their rebuilding status from 1988 while only 5 improved their status.

Although the outlook is worse, 6 stocks attained their escapement goals for at least 4 out of the last 5 years: Andrew Creek, Keta, Chickamin, Skeena, Upper Fraser and Columbia Upriver bright. Of these stocks, Andrew Creek, Keta and Skeena are classified as Rebuilding. The other 3 stocks are classified as Probably Rebuilding because of declines in recent escapements. Altogether, 12 stocks met their escapement goals in 1989 (more than 1988 but fewer than in 1986 and 1987) and more stocks continued to reach a higher percentage of their goal than during the base period.

Exploitation Rate Assessment

Fishery Indices

The fishery index measures exploitation rate changes over time for indicator stocks harvested by a fishery. The index was developed to estimate changes in fishery harvest rates. The utility of the index is dependent on how representative the indicator stocks are of the actual populations harvested in the fishery.

For 1989, the initial 1985 target reductions for fisheries with Pacific Salmon Commission catch ceilings were achieved in the Southeast Alaska troll fishery, the North/Central B.C. troll fishery, and the west coast Vancouver Island troll fishery. When 1985-1989 averages are considered, only the North/Central B.C. troll fishery has met the 1985 target reduction. The 1985 target reduction for southeast Alaska was achieved for the reported catch index, but not for the total mortality index (catch plus incidental mortalities). The average 1985-1989 total mortality index for the Southeast Alaska troll fishery remains 4 percentage points above the 1985 target reduction. The 1985-1989 average fishery index for the west coast Vancouver Island troll fishery remains 6 percentage points above the 1985 target reduction.

In 1989, the combined harvest rate by the Strait of Georgia sport and troll fisheries continued to exceed the initial 1985 target reduction by a substantial margin. The average 1985-1989 reduction in the fishery index is slightly over half the 1985 target reduction. A reason for this is that the average reduction for the sport fishery index is estimated to be only 4% less than the base period and, in 1989, is estimated to have increased to 28% above the base period. The troll fishery has, on average, achieved its target reduction.

The Washington/Oregon ocean troll and sport fisheries have maintained, on average,exploitation rates below base period levels. Note that indices reported for 1987 and 1988 differ substantially from the indices reported in TCCHINOOK (89)-1 because CWT recoveries from the Washington Buoy 10 sport fishery were incorrectly identified as ocean sport fishery recoveries in the historical database.

Stock Specific Trends

The stock-specific analyses in the Exploitation Rate Analysis monitor the response of stocks to fishery management actions, brood year survival and exploitation patterns, and stock contributions to fisheries.

For 17 stocks, recent exploitation rates could be compared to base period levels. Considering only changes greater than +2%, total mortalities by ocean fisheries have been reduced for 14 of the 17 stocks. The portion of total mortality accounted for by incidental fishing mortality has increased for 10 of the 17 stocks evaluated.

The Committee emphasizes that to maintain reductions or further reduce brood year ocean exploitation rates under a fixed catch ceiling policy, the abundance of chinook in the fishing areas must equal or exceed recent abundances. However, both the survival rate assessment and the stock contribution estimates indicate reduced survival of recent brood years for most of the major contributing indicator stocks. Without reductions in harvest pressures, in ocean and/or terminal fisheries, it is unlikely that spawning escapements needed to maintain progress in the rebuilding program will be attained.

Integrated Analysis

If the rebuilding program were proceeding as planned, we would expect fishery indices to be below 1985 target levels, brood year exploitation rates to decline to near MSY levels, and most of the escapement indicator stocks to be in the upper status categories.

Harvest rates in the ceiling fisheries have been reduced, but generally not to the 1985 target levels. Target reductions have been achieved or nearly achieved in the Southeast Alaska and North/Central B.C. ceiling fisheries and have not been met in the west coast Vancouver Island and Strait of Georgia ceiling fisheries. However, at this stage of the rebuilding program, it would be expected that harvest rate reductions in fisheries with Pacific Salmon Commission catch ceilings would be greater than the initial 1985 target reductions. Harvest rates in non-ceiling fisheries have generally declined.

Progress toward rebuilding for many of the stocks has been limited by poor survival and a failure to meet expected reductions in exploitation rates for ceiling fisheries. Reductions in stock exploitation indices were within 10% of their 1985 target levels for only 4 of the 7 stock groupings for which comparisons could be made.

With some exceptions, stock groups that have a majority of their fishing-related mortality in northern ceiling fisheries appear to be doing fairly well. Stock groups that have a majority of their fishing mortality in Strait of Georgia fisheries are typically classified as Probably Not Rebuilding or Not Rebuilding. The 2 stock groups that have a majority of their fishing mortality in U.S. non-ceiling fisheries have shown a mixed response.

Chinook abundance in the Southeast Alaska and North/Central B.C. troll fisheries is projected by the chinook model to be near the rebuilding period (1985-1989) average but above the long term (1979-1989) average. Abundance in the west coast Vancouver Island and Strait of Georgia fisheries is projected to be below the rebuilding period average and substantially below the long-term average. However, these projections of fishery abundance are optimistic because the current model does not incorporate the declines in short-term survival projected in the Exploitation Rate Analysis.

Poor survival is projected for broods returning in 1990 and 1991; only one stock group is projected to have a short-term survival index greater than the long-term average. If the rebuilding progress is to continue despite these reduced survivals, brood year exploitation rate reductions will be required. In particular, in order to meet the rebuilding goals for stocks significantly impacted by the Strait of Georgia and west coast Vancouver Island fisheries, additional management actions will be required to reduce harvest rates for these fisheries.

Qualifications

1. The distribution of stocks, by geographic location and stock-type, is still incomplete, particularly for Canadian spring and summer stocks, even though the number of stocks included in this report has more than doubled compared to the 1988 report. The number of stocks was increased principally to improve the reliability of the exploitation rate evaluation and to examine the consistency of responses between stocks.

2. Changing fishing patterns can confound interpretation of total exploitation rate analysis.

3. The Committee is concerned that current management strategies may have resulted in changes to the age and sex composition of chinook spawning escapements in a way that may impede progress towards rebuilding. In particular, size limit changes may increase escapements of males while decreasing escapements of females (males typically mature at an earlier age and smaller size than females). It should be noted that the optimum spawning escapements established by agencies are based on an age and sex composition that would have resulted from previous ocean management. If spawning escapement increases contain a disproportionate number of males, the productivity resulting from increased escapements will not achieve expected levels based on historical data.

Chinook Technical Committee Recommendations

1. Further management action should be taken to reduce stock exploitation rates (including compensation for increased incidental mortalities per reported catch) in order to increase the probability of reaching escapement goals by 1998. With the current management regime, it is expected that many indicator stocks will not achieve their escapement goals by 1998, since the assessed status of the escapement indicator stocks is poorer for 1989 than for 1988, survival projections indicate reduced chinook abundance in 1990 and 1991, and our assessments indicate that the current ceilings have not reduced harvest rates to the initial 1985 target levels for 3 out of 4 fisheries.

The exploitation rate reduction required to rebuild stocks will depend upon stock productivities, the change in brood survival rates, stock exploitation patterns, and abundance in ceiling fisheries in which the stock is primarily harvested. In general, the management actions required to reduce harvest rates will be proportional to the decreases in chinook abundance.

2. Policy issues and information needs for interpretation of the pass-through provision should be resolved. A complete assessment of cumulative pass-through impacts on rebuilding progress is needed to complete the rebuilding assessment.

3. Policy issues of what constitutes rebuilding must be resolved so the Committee can complete its assessment of rebuilding progress (e.g. appropriate stock groupings; proportion of the stocks rebuilding, etc.).

4. The Committee recommends attention to the following information concerns and needs:

(a) The effect of regulatory changes on the potential productivity of naturally spawning stocks should be assessed. An increased commitment to conduct consistent escapement surveys, including sex ratio and age composition data, is needed to evaluate expected production and returns by brood year.

(b) Indicator stock programs should be reviewed to determine if representation of production regions and stock types is adequate and if tagging levels for the indicator stocks are sufficient. The Committee is especially concerned about the representation of spring and spring/summer stocks, and the development of standardized definitions for run-timing classifications of stocks.

(c) Troll fisheries and chinook non-retention periods should be annually sampled to assess the impacts of changes in fishing patterns and to verify parameters used in estimating incidental mortalities. Changes in spatial and temporal fishery patterns have affected fishing effort and perhaps chinook encounter rates.

(d) Consistent and standardized recovery programs for CWT fish at hatcheries and on spawning grounds should be established. In addition, tagging of juvenile fish should be standardized for enumeration of marks, total release numbers, and tag retention estimation procedures.