Evaluation of NEA haddock Harvest Control Rules Alexey Russkikh, Anatolii Chetyrkin, Yuri Kovalev, Bjarte Bogstad, and Gjert Dingsør
Background Northeast arctic haddock has been managed by harvest control rules since 2004 The existing rule has evolved from the first rule proposed by the Joint Norwegian-Russian Fisheries Commission (JNRFC) in 2003 and ICES has previously found it to be in agreement with the precautionary approach At its 45 th session in October 2015, JNRFC decided that a number of alternative harvest control rules (HCRs) for Northeast Arctic cod and haddock and Barents Sea capelin should be evaluated by ICES
Existing HCR TAC for the next year will be set at level corresponding to F MSY (0.35) The TAC should not be changed by more than +/- 25% compared with the previous year TAC. If the spawning stock falls below B pa (80 000t), the procedure for establishing TAC should be based on a fishing mortality that is linearly reduced from F MSY at B pa to F= 0 at SSB equal to zero. At SSB-levels below B pa in any of the operational years (current year and a year ahead) there should be no limitations on the year-to-year variations in TAC.
Existing HCR F 0.35 80 000t SSB
2015 assessment 1.2 1 0.8 0.6 0.4 0.2 0 1950 1953 1956 1959 1962 1965 1968 1971 1974 1977 1980 1983 1986 1989 1992 1995 1998 2001 2004 2007 2010 2013 1200000 1000000 800000 600000 400000 200000 0 Spawning stock biomass, SSB Fishing mortality, F F lim F msy, F target 1950 1953 1956 1959 1962 1965 1968 1971 1974 1977 1980 1983 1986 1989 1992 1995 1998 2001 2004 2007 2010 2013 SSB 95% confidence interval B pa F bar 4-7 95% confidence interval
Historic HCR performance
Request JNRFC asks ICES to explore the consequences of the following harvest control rules: 1. The existing harvest control rule, but with F target =0.27 instead of 0.35 2. The existing harvest control rule 3. The existing harvest control rule, but with F target =0.43 instead of 0.35 4. The existing harvest control rule, but with a constraint of maximum 10% TAC variation from year to year instead of a 25% constraint which is presently used 5. The existing harvest control rule, but with no constraint of maximum TAC variation from year to year 6. The existing harvest control rule, but without limitation +25%
Long term simulations In accordance with the ICES guidelines for evaluation of Management Plans Software: NE_PROST (Kovalev; Excel/Visual Basic) 5 000 individual runs of 100 years were made for each HCR, long-term evaluations statistics were collected for the last 80 years HCR is precautionary in accordance with the ICES standard when the short, medium and long-term probability that the SSB falling below B lim is no more than 5%
Long term simulations The simulation model accounts for variation between years for the following processes: Recruitment; lognormal distribution with autocorrelation included Density-dependent growth Density-dependent maturation Assessment error; random noise Constant parameters Natural mortality (including cod predation, mean 1984-2014) Selection pattern (mean 1995-2014) No implementation error
Results HCR No. 1 2 3 4 5 6 Target F 0.27 0.35 0.43 0.35 0.35 0.35 TAC Constraint % (SSB > Bpa) 25 25 25 10 N/A + :N/A; 25 Mean F realised 0.25 0.32 0.38 0.28 0.35 0.39 Prob (SSB<Blim) in % 0.6 2.3 4.9 3.3 0.8 3.4 Prob (SSB<Bpa) in % 3.5 9.7 16.7 10.7 6.9 13.9 Mean catch 125 130 133 115 136 138 Median catch 106 109 111 103 109 113 Standard deviation of catch 81 91 98 74 100 103 Median TSB 512 440 388 539 403 373 Median SSB 276 214 171 282 192 167 Median annual change in Catch, % 21 24 27 11 31 32 Mean weight in catch, kg 1.59 1.52 1.46 1.59 1.49 1.45 % of years + TAC constraint applied 37.0 38.2 37.6 58.2 N/A N/A % years TAC constraint applied 21.5 17.9 13.2 16.8 N/A 22.8
Simulated spawning stock biomass, SSB 90% conf. int. 50% conf. int. Median value B pa Note: Rule 4 has different scaling on y- axis
Simulated fishing mortality, F F lim
Simulated catch
WKNEAMP conclusions 1. Do not increase F target (not precautionary) 2. The proposal of 10% limitation of annual TAC variability (HCR 4) will decrease average yield. Among the six HCRs tested, the current HCR (2) performs best in terms of average yield, stability of yield and degree of precaution. ICES. 2016. Report of the second workshop on Management Plan Evaluation on Northeast Arctic cod and haddock and Barents Sea capelin (WKNEAMP-2), 25 28 January 2016, Kirkenes, Norway. ICES CM 2016/ACOM:47. 104 pp.
Advice Scenarios with a higher F (HCR 3, 5 and 6) than used presently (HCR 2) result in 0% - 4% higher long-term median yield, with an increase in inter-annual TAC variability between 13% and 36% The median long-term SSB expected with the higher F HCR (3) is around 20% lower than under the presently used HCR HCRs 1 (lower target F) and 4 (10% limit on interannual TAC variation) lead to lower long-term catch, lower inter-annual TAC variability and higher median long-term SSB than HCR 2. ICES Advice 2016, Book 3
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