North Sea Case Study

UNCOVER Report Writing Workshop

Holte

February 2010

“If any trawling ground be over-fished, the trawlers themselves will be the first persons to feel the evil effect of their own acts. Fish will become scarcer, and the produce of a day’s work will diminish until it is no longer remunerative.

When this takes place (and it will take place long before the extinction of the fish) trawling in this locality will cease, and the fish will be left undisturbed, until their great powers of multiplication have made good their losses, and the ground again becomes profitable to the trawler.

In such circumstances as these, any act of legislative interference is simply a superfluous intervention between man and nature.”

Report of the Commissioners, 1866

Status Quo

Stock SSB in relation to

precautionary limits

F in relation to precautionary

limits

F in relation to high long-term

yield

F in relation to agreed target

Cod Reduced reproductive

capacity

Increased risk Overfished Above target

Plaice Full reproductive

capacity

Harvested sustainably

Overfished Below target

Herring Increased risk Harvest sustainably

Appropriate Above target

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.”

Status Quo - Cod

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

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.

Cod

• Despite measures cod has not recovered

• Low F, but Recruitment has been recently poor

• Stock structure and diversity

• High F on low ages prevents growth, even if recruitment is high.

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.

• FCUBE is in FLR – include in future evaluations?

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?• Impact of climate is highly speculative and often

contradictory• Should reference points (MSY) be multispecies?

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.”

Status Quo - Plaice

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

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

Plaice

• Stock age diversity did not impact on recruitment• Allowed stock to take advantage of low F• Low F laid foundation of recovery, still needed high Rec.

i.e. low F does not guarantee recovery.• Compare to situation Cod• 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.

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.”

Status QuoHerring

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.

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

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.

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 implementation and enforcement need to be included in plan evaluation?

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.– Recovery vs rebuilding

• 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.

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 – possible impact of substocks

• The importance of herring in multispecies models has not been fully explored.

Impact of precautionary plans

Stock Previous status

Precautionary plan?

What happened?

Cod Collapsed Yes Not recovered

Plaice Collapsed ? Recovered

Herring Healthy Yes Danger of Collapse

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.

General thoughts

• How precautionary is precautionary?• Cannot recover without low F – some control –

implementation error and enforcement• But you also need high Rec – no control• Plans should be robust to stuff we can’t control• Plans need some target time and acceptable level of risk

to be defined• Can you attribute recovery to plan – time taken• Socio-economics needs to be included in evaluations• Top down vs Local management / Results Based

Management - JAKFISH• Further development of MSE approach is recommended

by ICES and STECF

NSCS Report

• Models and results• Distinguish what has directly come from

UNCOVER and what has been ‘reviewed’.• WP2 - input• Socio-economics• Stakeholder participation• Precautionary• Section 3.3.1 (3a)• Wood / trees