1. Mixed fisheries issues for North Sea Cod
EFIMAS CONFERENCE, MARCH 2008, BRUSSELS
Mixed fisheries issues for North Sea Cod
Clara Ulrich, Katell Hamon, (Stuart Reeves)
DTU Aqua. National Institute of Aquatic Resources
Danmarks Tekniske Universitet
ICES SGMIXMAN, FP6 AFRAME, (FP6 EFIMAS)

2. Issue : technical interactions cod-haddock
Low cod biomass High haddock biomass
Effects of cod recovery plan not as wide as expected
Stocks caught together by main demersal fleets
DTU Aqua. National Institute of Aquatic Resources
Danmarks Tekniske Universitet

3. How might TACs work in such situations?
Low cod TAC, taken with low effort / high haddock TAC, taken with a higher level of effort
Fleet dilemna:
stop fishing when cod TAC caught and underutilise haddock TAC (”min effort” scenario)
go on fishing until haddock TAC caught and get overquota catches of cod (”max effort” scenario)
What are the long-term effects of such scenarios?
simulation work, with 11 fleets and ICES/EU management procedures
DTU Aqua. National Institute of Aquatic Resources
Danmarks Tekniske Universitet

4. Results Min Effort Max Effort (Hamon et al., 2007)
Min effort : cod reovery within few years, but underutilisation of haddock. Max effort : no cod recovery but optimal haddock exploitation. (official) Cod data gets bad (corresponding to restrictive TAC only, green catches), leading to wrong assessment (green Fbar)
Black : “Real truth” (simulated underlying population)
Green : “Perceived truth” (seen from VPA’s eyes and used for deciding upon management)
DTU Aqua. National Institute of Aquatic Resources
Danmarks Tekniske Universitet

5. The next step : providing mixed-fisheries advice
Question : which single-species TAC should be proposed to be consistent across stocks?
Methodology : The Fcube approach (ICES MixMan )
Main focus : fleets (vessel types) and fisheries (activity types)
Each fleet has its own set of incentives based on its set of quota shares
Hypotheses are proposed on their likely behaviour and level of effort (max, min, valuable species, days at sea regulation…)
corresponding landings (< quota share) and overquota catches (> quota share) are estimated
DTU Aqua. National Institute of Aquatic Resources
Danmarks Tekniske Universitet

6. Example : investigating effects of 2007 TACs
Cod, haddock, whiting, saithe, sole, plaice, Nephrops
Very restrictive cod TAC, unrestrictive whiting TAC
All international North Sea fleets (19)
Scenarios :
”min” (stop fishing when first quota exhausted)
”max” (stop fishing when last quota exhausted)
”value” (effort towards most valuable quota shares)
”status quo” (unchanged effort between 2006 and 2007)
”DAS reduction” (partial reduction of cod-targeting fisheries)
”cod” (action necessary to avoid cod overquota for all fleets)
DTU Aqua. National Institute of Aquatic Resources
Danmarks Tekniske Universitet

7. Results ICES SGMixMan, 2008) Saithe TAC Haddock TAC Plaice TAC Cod TAC
Sole TAC
Saithe TAC
Haddock TAC
Plaice TAC
DTU Aqua. National Institute of Aquatic Resources
Danmarks Tekniske Universitet

8. Results DTU Aqua. National Institute of Aquatic Resources
Danmarks Tekniske Universitet

9. Conclusions
Inconsistent 2007 TACs; single-species management objectives cannot be reached simultaneously
At current levels of effort, large over quota catches of cod are estimated to have happened in 2007
It is possible to test the biological and economic effects of alternative consistent TACs (short-, medium- and long-term), as a basis for robust mixed-fisheries management plans
This approach can be extended to non-target species and broader ecosystem approach
DTU Aqua. National Institute of Aquatic Resources
Danmarks Tekniske Universitet

10. Comments from the customer
ICES Study Group on Mixed-fishery Management
EU FP6 Aframe project
STECF Sub-groups
Effort management
Cod recovery
Context
Tool to be used in ICES, annual, short-term advice
Not EFIMAS!

11. Management advice; TACs and beyond
TAC advice
Based on annual ICES assessments
Implicit assumption, TAC acts to restrict F
i.e. when TAC exhausted, fishing stops
Effort advice
No scientific basis at present
Effects
Direct – if available effort limiting
Indirect – change activity if more effort available there
Other management measures
Indirect; fleets will change behaviour in some way.

12. Fcube in practice Two components Original intention Recent context
Retrospective
Forecast
Original intention
Derive sets of consistent TACs for mixed fisheries
But:
very dependent on assessment quality
Very data demanding
Risk of falling back into the prediction trap.
Recent context
Not just TACs, also effort, closed areas, cod avoidance measures
Increased interest in non-traditional species, e.g. skates and rays

13. Effort trends by major gear categories
Recent Fs (standardised to mean)

14. Fcube in practice - conclusions
Understanding the past is at least as important as forecasting the future
How has fleet activity changed in response to past management and conditions?
Forecast better used in an indicative, rather than prescriptive, way.
Fcube approach could be effective in a participatory context
The inclusion of information on fleets and their fisheries is essential in the current context
Fleets – link to economics
Fisheries – link to non-target species & other ecosystem components
Fishing activity is linked to fishing mortality