Horse mackerel 9a long-term Management Plan MSE analysis M Azevedo (1) , H Mendes (1) , G Costas (2) , E Jardim (3) , I Mosqueira (3) , F Scott (3) (1) IPMA-Lisboa; (2) IEO-Vigo; (3) JRC-ISPRA PELAC meeting Denn Haag, 11 July 2017
Outline • Process (roadmap) • Stock assessment data/method: 1992-2016; Statistical catch-at-age with AMISH (settings: hom9a stock annex) • Management Strategy Evaluation (MSE) HCR and management options following questionnaire and meetings with stakeholders 2
• Results Short-term (ST): 2017-2020; 2017-2027 Long-term (LT): 2070-2080; 2017-2080 for Precautionary considerations Catch Median; P10%, P90%, Interannual Variation (IAV) IAV 1 : mean (catch y /catch y-1 ) IAV 2 : sum (catch y -catch y-1 ) IAV 3 : mean (catch y -catch y-1 ) Fishing mortality (F) Median F P(F > F MSY ) Spawning Stock Biomass (SSB) Median P(SSB < B lim ) P(SSB < MSY B trigger ) • Robustness/Sensitivity Selectivity, Status quo period, Productivity 3
Process Focus group meetings on Management Plan for hom9a • Oct 2014, SWWRAC/PELAC meeting, Madrid First debate on Management plan • Nov 2014, SWWRAC/PELAC webex meeting Type of harvest control rule (TAC, F or Harvest Rate) • Feb 2015, SWWRAC meeting, Lisbon Refinement of HCR type and Biological Reference Points • Jul 2015, PELAC meeting, Denn Haag Preliminary estimates for horse mackerel (hom9a) Biological Reference Points - BRPs (WD) 4
• Feb 2016, PELAC meeting, Denn Haag BRP estimates (2015 assessment data); Rationale accepted by PELAC • Mar 2016, SWWRAC stakeholders meeting, Matosinhos Stakeholders feedback on options for catch stability; Level of catch for F by-catch Jul 2016: ICES Stock Assessment WGHANSA • Oct 2016, PELAC meeting, Denn Haag BRP estimates (2016 assessment data) accepted by ICES for advice; results from 1st set of stochastic simulations (MSE short-cut approach); HCR and BRPs acepted by PELAC; questions to stakeholders on assumptions & MP options -> produce questionnaire to be sent to stakeholders • Nov 2016, SWWRAC/PELAC meeting, Lisbon Synthesis of stakeholders response to questionnaire; set rodmap for further analysis Feb 2017: Benchmark hom9a WKPELA • Jul 2017, SWWRAC/PELAC meeting, Matosinhos Preliminary results from stochastic simulations using full MSE; stakeholders feedback on HCR, options and metrics • Jul 2017, WGHANSA meeting, Bilbao Feedback from scientists on full MSE 5
MSE
• Operating Model - Productivity (Recruitment) - Biological characteristics (natural mortality, mean weight, proportion mature) - Starting conditions: assessment with data 1992-2016 • Management Procedure – Statistical catch-at-age (SCA: a4a) stock assessment (mimic AMISH) with observation error – Advice from short-term forecast (as in hom9a stock annex) – Management = Advice, fully implemented usually designated by full MSE 7
Management scenarios HCR Fishing mortality F MSY (0.11) F by-catch (0.01) B lim B trigger (103 th t) (181 th t) Spawning Biomass F MSY target year: 2025 TAC: TAC y+1 =Catch y-1 TAC y+1 =mean[Catch y-3 :Catch y-1 ] TAC y+1 =TAC y TAC change limit: No; ± 15% and ± 20% catch constraint 8
Simulations - 200 populations projected until 2080 - 2 productivity scenarios: geometric mean hockey-stick (BRPs) SSB-R with 90%CI 12000 8000 recruits 6000 4000 2000 0 0 200 400 600 800 SSB 9
Results • AMISH (current assessment method) & SCA (a4a) Correlations: in the range 0.71- 0.95; high in most recent years which are initial conditions for simulations 10
Hockey-stick; F MSY in 2025; option catch ± 15% million blue shaded area : 80% confidence interval; blue line : median values th t green line : illustrates the trajectory of one of the 200 simulated populations th t TAC y+1 =Catch y-1 TAC y+1 =mean[Catch3 yrs ] TAC y+1 =TAC y No change limit 11 y: assessment interim year
Zoom on catch stability over time: option catch ± 15% 2017-2020: 2017-2020: 2017-2020: 2017-2020: IAV 1 = 10% IAV 1 = 2% IAV 1 = 4% IAV 1 = 7% IAV 2 = 58 t IAV 2 = 32 t IAV 2 = 25 t IAV 2 = 75 t IAV 3 = 15 t IAV 3 = 8 t IAV 3 = 6 t IAV 3 = 19 t 12
True F and Perceived F: option catch ± 15% F MSY Perceived F is higher than realized (true) F realized F doesn´t reach F MSY 13
Hockey-stick; F MSY in 2025; option catch ± 20 % TAC y+1 =Catch y-1 TAC y+1 =mean[Catch3 yrs ] TAC y+1 =TAC y No change limit 14
True F and Perceived F: option catch ± 20% Very similar to option catch ± 15% IAV 1 : around 1% max IAV 2 : 5t max IAV 3 : 2t 15
Hockey-stick; F MSY in 2025; option catch ± 15% Catch and SSB in thousand tonnes TAC y+1 =Catch y-1 TAC y+1 =mean[Catch3 yrs] TAC y+1 =TAC y No change limit METRICS ST LT ST LT ST LT ST LT 2017-27 2070-80 2017-27 2070-80 2017-27 2070-80 2017-27 2070-80 Catch Median catch 47 41 45 41 51 41 48 40 10 th perc. Catch 37 34 38 34 41 34. 37 32 90 th perc. catch 57 50 53 50 61 50 68 49 IAV 1 5% <1% 5% <1% 2% <1% 6% <1% Fishing mortality P (F > F MSY ) 2% 3% <1% 4% 23% 2% 29% 1% Median F 0.105 0.107 0.09 0.107 0.114 0.104 0.113 0.101 Precautionary considerations Median SSB 459 347 486 345 425 352 412 367 P (SSB < B lim ) 0% 0% 0% 0% 0% 0% 0% 0% P (SSB < B trigger ) 0% 0% 0% 0% 0% 0% 0% 0% 2017-2080 16
± 20% vs ± 15% values in % TAC y+1 =Catch y-1 TAC y+1 =mean[Catch3 yrs] TAC y+1 =TAC y No change limit METRICS ST LT ST LT ST LT ST LT 2017-27 2070-80 2017-27 2070-80 2017-27 2070-80 2017-27 2070-80 Catch Median catch +2 0 +2 0 0 0 0 0 10 th perc. Catch -3 0 -3 0 -2 0 0 0 90 th perc. catch +5 0 +2 0 0 0 0 0 IAV 1 0 0 0 0 0 0 0 0 Fishing mortality P (F > F MSY ) +1 0 0 +2 0 0 0 0 Median F <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 Precautionary considerations Median SSB -1 +0.01 0 +0.01 -0.01 0 <0.01 +0.01 P (SSB < B lim ) 0 0 0 0 0 0 0 0 P (SSB < B trigger ) 0 0 0 0 0 0 0 0 2017-2080 17
Robustness • Selectivity accomodates pop structure over time - P(SSB < B lim ) = 0 - Max median Catch ≤ 12% - Max IAV 1 = 1% • Status quo (3 year mean) - P(SSB < B lim ) = 0 - Max median Catch ≤ 5% - Max IAV 1 <1% 18
Recruitment (low=40% geometric mean) F MSY in 2025; option catch ± 15% P1=P(SSB < B lim ) P2=P(SSB < MSY B trigger ) 2017-2080: 2017-2080: 2017-2080: 2017-2080: P1= 42/80% P1= 56/78% P1=0/0% P1=0/0% P2=81% P2=80% P2=40% P2=20% Average probability across 200 populations MSY B trigger B lim Maximum probability over the 200 populations 19
Recruitment (low=40% geometric mean) F MSY in 2025; option catch ± 20% P1=P(SSB < B lim ) P2=P(SSB < MSY B trigger ) 2017-2080: 2017-2080: 2017-2080: 2017-2080: P1=5/30% P1=12/52% P1=0/0% P1=0/0% P2=71% P2=73% P2=37% P2=20% P1 decreases in relation to ± 15% MSY B trigger B lim 20
Summary of results • The harvest control rule proposed by stakeholders for the Long-Term Management Plan for Southern Horse Mackerel (hom9a), with F MSY (0.11) target year in 2025, B lim =103 th t and MSY B trigger =B pa =181 th t, is precautionary for all the management scenarios explored. • There are marginal differences between the options 15% and 20% TAC change limits. • The LT catch is estimated to be around 40 000 t (median value) but in the short- term the IAV in catch is smaller for the management option TAC y+1 =TAC y , of 2% (between 5-6% for the other options). • Sensitivity tests indicate that the HCR combined with catch stabilizing mechanisms is robust to changes in selectivity and status quo peridod. In a scenario of low recruitment, only catch options “TAC y+1 =TAC y “ and “no TAC change limit”, are precautionary. With 20% change limit there is lower prob of falling below B lim in all scenarios. 21
Follow up ? 22
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