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ICES Symposium on management strategies - SFMS-25

ICES Symposium on management strategies - SFMS-25. FLEET-BASED SHORT-TERM ADVICE IN MIXED FISHERIES – THE F 3 APPROACH Clara Ulrich, B.S. Andersen, H. Hovgård, P. Sparre (DIFRES), A. Murta (IPIMAR), D. Garcia (AZTI), J. Castro (IEO). Background – ICES WKMIXMAN.

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ICES Symposium on management strategies - SFMS-25

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  1. ICES Symposium on management strategies - SFMS-25 FLEET-BASED SHORT-TERM ADVICE IN MIXED FISHERIES – THE F3 APPROACH Clara Ulrich, B.S. Andersen, H. Hovgård, P. Sparre (DIFRES), A. Murta (IPIMAR), D. Garcia (AZTI), J. Castro (IEO)

  2. Background – ICES WKMIXMAN • Needs to find a method for mixed-fisheries advice to replace MTAC. Issues raised: • Mismatch between the allocation of effort to individual fleets and the relative stability within European fisheries • Constant catch compositions of fleets in the forecast • High sensitivity of results to the inputs, both in terms of fleet/fishery catch data and policy weightings • No respect of management objectives for all stocks • Requirements for alternative methods (MoU) : • Simple model • Based on currently available and accessible data • Account for changes in fishing practices

  3. Background - TEMAS model and TECTAC project • Modelling management strategies in multifleet multispecies fisheries Y+1? Year Y With data Y-1 With effect Y+1

  4. F3 – Fleet and Fisheries Forecast • Cornerstone : catch AND effort data Fleet AND métiers (fisheries) Fleet (vessels) Métier (trips) Species (catches) • Data : • catch and effort database : each vessel to a fleet, each trip to a fishery • F and biomass estimates by stock • Forecast by stock CATCHABILITY EFFORT

  5. F3 - Main assumptions • F=qE • A vessel in a fleet can engage in several metiers during the year • The catchability of a metier can be measured and assumed known – but not the catchability of a vessel (fleet) • The overall catchability of a vessel (fleet) is forecasted as weighted mean of catchability by metier and time spent in each metier • The relative stability by country also applies at the fleet level (especially in right-based regimes) • The fleet will balance its total effort according to its quota shares, and overquota catches might occur • Options : MAXEFFORT : fish until last quota exhausted / MINEFFORT : stop fishing when first quota exhausted

  6. F3 - Overview Effort (Fl,Mt) Catches (Fl,Mt,St) Assessment F(St) PartialF(Fl,Mt,St) EffortDistr(Fl,Mt) Q(Fl,Mt,St) assumption ForecastEffortDistr(Fl,Mt) ForecastQ(Fl,Mt,St) Forecast F(St) ForecastQ(Fl,St) ForecastF(Fl,St) Management rule Rel. Stab (Fl,St) Forecast Effort (Fl,St) (MAX,MIN,WEIGHTED MEAN Effort bound…) Forecast TAC(St) Forecast Effort (Fl) Forecast F (Fl,Mt,St) Forecast B(St) Forecast OverQuota (Fl, St) Forecast Catches (Fl,Mt,St) Forecast landings (Fl, St)

  7. F3 – WGHMM06 – Southern Stocks – Trial runs • 8 Stocks • MEGRIM (*2), HAKE, ANGLERFISH, NEPHROPS (*4) • 6 Fleets and 13 Fisheries: • PT artisanal : 3 fisheries (target species) • PT trawl : 2 fisheries (target species) • SP artisanal : 2 fisheries (areas) • SP gillnet : 3 fisheries (gear*target species) • SP longline : 1 fishery • SP trawl : 2 fisheries (areas) • 3 scenarios • 2005 ACFM proposal • 2006 TAC • Southern Hake recovery plan (reduce F by 10%)

  8. Southern Stocks – Sc1 ACFM proposal (trial runs) MAX EFFORT MIN EFFORT (bounded) NOT COMPATIBLE!!

  9. Southern Stocks – Sc2 TAC 2006 (trial runs) MAX EFFORT MIN EFFORT Effort by fleet, MINEFF vs MAXEFF

  10. Southern Stocks – Sc2 TAC 2006 (trial runs) MAX EFFORT MIN EFFORT F landings F total

  11. Southern Stocks – Sc3 Hake recovery plan (trial runs) MAX EFFORT MIN EFFORT

  12. F3 –Southern Stocks - conclusions • Single-species TAC are not efficient tools for reducing F. They induce unaccounted fishing mortality and bias in assessment • Single species management plans cannot be achieved without considering mixed-fisheries interactions • It would be possible to formulate mixed-species TAC by fleet including some management objectives and priorities • Mixed-fisheries management should ideally be at the fleet/vessel level, rather than at the fishery or stock level, to account for changes in activity • No good input and assessment data – results are only used for demonstration

  13. F3 - Discussion • A process model; mathematically simple, transparent. • Assume relationship between F and E, needs reliable single species forecast • Uses landings and effort (better use of existing data than MTAC) • Good data requirements. Requires preliminary work to define exhaustive fleets and fisheries • Compatible with relative stability • Assumption on fixed quota share allocation between fleets • Based on manageable units, links with economics and with effort regulation • Sensitivity to aggregation level and fleet-fisheries definitions? • No assumptions on fixed catch composition (only fixed catchability by metier) • Catchability varies between vessels, time period etc. Measured on landings! • Can account for finer analyses • More complexity would make it less tractable

  14. F3 – Future developments • Needs additional testing and sensitivity analysis • Link with economics – relation with the EIAA model used for economic advice • How to deal with age-based approach? • Improvement of the relationships between effort and mortality : better effort definitions and catchability estimates (cf TECTAC, CAFÉ…) • Inclusion of flexibility in effort allocation by fishery – behavioral analysis of metier choice (cf Andersen et al., SFMS 32) • Is that of use for management? Can we implement mixed species TACs for the individual fleets?

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