North Sea Case Study

1. North Sea Case Study UNCOVER Report Writing Workshop Holte February 2010

2. Status Quo

3. Status Quo - Cod • “…ICES classifies the stock as suffering reduced reproductive capacity and as being at risk of being harvested unsustainably. • SSB has increased since its historical low in 2006, but remains below Blim. • Fishing mortality declined after 2000, but in 2008 increased, predominantly as a consequence of increased discarding and is currently estimated to be between Flim and Fpa. • The 2005 year class is estimated to be one of the most abundant amongst the recent below-average year classes. The 2008 year class is estimated to be one of the lowest in the series.”

4. Status Quo - Cod

5. Status Quo - Cod • SSB declined since late 90s. • Recent small increase as 2005 year class matures combined with relatively low F. • Recruitment – 1996 last large year class. 2005 relatively high. But 2006 and 2007 weak. 2008 expected to be weak • F has decreased but recent values are uncertain. F increased recently due to increase in discarding. • Discard mortality > human consumption mortality

6. Management - Cod • Former recovery plan (2004) was not precautionary – cut in quota not matched by cut in effort. • Another recovery plan (2009) was evaluated • Is precautionary if implemented and enforced. • Effort management introduced (2009) – gear and metier dependent.

7. Lessons learned - Cod • Despite measures cod has not recovered • Low F, but Recruitment has been recently poor • Stock structure and diversity (RASER) • High F on low ages prevents growth, even if recruitment is high.

8. Lessons learned - Cod • Mixed fishery – current plan is single species • Evaluation of plan was single species (e.g. no cannibalism) – may overestimate probability of recovery • Multispecies modelling (SMS) demonstrate predation is key biological process • Multispecies modelling increases uncertainty – SMS vs EwE • Mixed-species nature of fishery and international dimension are two main factors contributing to decline (Bannister, 2004). • WKMIXFISH 2009 – evaluated consistency of single stock plans. Cod fared badly – over quota catches. Effort restrictions should help. • SMS model – mesh size changes. Increases led to higher probability of recovery.

9. Lessons learned - Cod • Specify ‘recovery’ – HCRs in 2008 evaluations had no agreed criteria • Substocks important? • Impact of environmental change? Warming lead to reduction in recruitment (STECF 2007). • Stock shifted northward and deeper? – highly speculative and often contradictory • Should reference points (MSY) be multispecies?

10. Status Quo - Plaice • ICES classifies the stock as having full reproductive capacity and as being harvested sustainably. • SSB is estimated to have increased above the Bpa. • Fishing mortality is estimated to have decreased to below Fpa and Ftarget. • Recruitment has been of average strength from 2005 onwards. The recruitment in 2008 is just below the long-term average.”

11. Status Quo - Plaice

12. Status Quo - Plaice • STECF advised a recovery plan (2003) • ICES proposal for a multi-annual plan tabled (2005) • No agreed EU – Norway plan • EU agreed long-term management plan (2007). Uses TAC and effort restrictions. • Evaluated in 2008. • Not yet been concluded if plan was precautionary

13. Lessons learned - Plaice • Plaice – recovered - why? • Reduction in F – driven by? • Management plan • Reduction in fleet capacity • Fuel prices drive down effort • STECF 2009 – too soon to attribute • Suggests inclusion of socio-economics in evaluation of proposed plans is essential

14. Lessons learned - Plaice • Stock age diversity did not impact on recruitment • Allowed stock to take advantage of low F – compared to Cod • Low F laid foundation of recovery, still needed high Rec. i.e. low F does not guarantee recovery. • Cooler water may reduce future recruitment ? • Inclusion of biological information (e.g. TEP) may lead to alternative perception of stock status and ref pts? • Question is now – how to prevent future collapse – precautionary plan. Recommended to use MSE.

15. Status Quo - Herring • “…ICES classifies the stock as being at risk of having reduced reproductive capacity and harvested sustainably. • The SSB in autumn 2008 was estimated at 1.0 million t, and is expected to remain below Bpa (1.3 million t) in 2009. • F2-6 in 2008 was estimated at 0.24, above the management target F2-6 (for this state of the stock = 0.14). • The year classes since 2002 are estimated to be among the weakest since the late 1970s.”

16. Status QuoHerring

17. Status Quo - Herring • Spawning stock biomass has fluctuated: • ~ 4.5 million tonnes in the late 1940s • less than 100 000 tonnes in the late 1970s • Demonstrated robustness in relation to recovery from low levels once fishing mortality is curtailed in spite of recruit-ment levels being adversely affected.

18. Status Quo - Herring • Management plan 1996 – reviewed and adapted every few years. • Precautionary ref pts adopted in 1998. • Previous plan was precautionary. • Critical issues is risk of SSB falling below Blim • EU-Norway adjust plan to account for poor recruitment (2008) – quotas to reduce F. • New plan also precautionary • Even though the current and previous management plans were considered “precautionary”, the stock declined below biomass targets in the mid-2000s. • This was primarily caused by a change in productivity of the stock • Exacerbated by the failure of the managers and industry to adhere to the existing management plan

19. Status Quo - Herring • The harvest control rule was revised again in 2009 • Reduction of the effective target fishing mortality through a change in trigger biomass. • SSB is expected to increase in 2010 & 2011 • Indicates current management can reverse the decline and stabilize it above the present level. • The 2008 year class is within the range of recent low recruitments • ICES assumes that the recruitment will remain at the low level.

20. Lessons learned - Herring • Larval survival - each spawner now produces less than one recruit per year. • Specific causes are unknown; the pattern in recruitment from 1970 to 2005 appears similar to environmental signals in the North East Atlantic such as the Atlantic Multidecadal Oscillation. • Change in productivity combined with failure to adhere to the existing management plan • Suggests that socio-economics and enforcement need to be included in plan evaluation?

21. Lessons learned - Herring • After collapse in 1970s, only three of the four North Sea herring stocks actually recovered, the fourth stock (Downs) taking substantially longer to recover. • Recovered stocks might not be as productive. • Sub-stocks – work on herring West of British Isles – fail to detect overexploitation - overestimate the probability of recovery and underestimate the risk of stock collapse.

22. Lessons learned - Herring • Compensation in recruitment has occurred in North Sea herring, and it was stronger after the collapse of the stock • There is more variability in recruits per unit spawning stock size when the stock is smaller – impact of substocks • The importance of herring in multispecies models has not been fully explored.

23. Generic HCRs • STECF 2008- codoid and herringoid • Picking max of F0.1 and Fsq was less effective than picking F0.1. • Inter-species comparisons not carried out. • STECF recommended the approach be developed.

24. Impact of precautionary plans

25. General thoughts • Cannot recover without low F – some control • But you also need high Rec – no control • Plans need some target time and acceptable level of risk to be defined • Attributing recovery to plan – time taken • Is recovered stock ‘the same’? • Socio-economics needs to be included in evaluations • Fish stocks can be threatened with unsustainability even if not exploited • Is interaction between env and exploitation too complicated to model? • How precautionary is precautionary? • Further development of MSE approach is recommended by ICES and STECF • Results Based Management • Top down vs Local management