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Biomass From an Ecosystem Based Fisheries Management Perspective. By John Pope NRC (EUROPE) LIMITED

Biomass From an Ecosystem Based Fisheries Management ... Pope_MAREFRAME_… · SSB cod SSB haddock SSB saithe SSB whiting SSB plaice*0.1 SSB sole SSB (N B Plaice scaled to improve

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Page 1: Biomass From an Ecosystem Based Fisheries Management ... Pope_MAREFRAME_… · SSB cod SSB haddock SSB saithe SSB whiting SSB plaice*0.1 SSB sole SSB (N B Plaice scaled to improve

Biomass From an Ecosystem Based FisheriesManagement Perspective.

By John PopeNRC (EUROPE) LIMITED

Page 2: Biomass From an Ecosystem Based Fisheries Management ... Pope_MAREFRAME_… · SSB cod SSB haddock SSB saithe SSB whiting SSB plaice*0.1 SSB sole SSB (N B Plaice scaled to improve

Biomass is rather likemoney in a Bank

Page 3: Biomass From an Ecosystem Based Fisheries Management ... Pope_MAREFRAME_… · SSB cod SSB haddock SSB saithe SSB whiting SSB plaice*0.1 SSB sole SSB (N B Plaice scaled to improve

Basics

In the long run Biomass declines as fishing increases.

Catch at first increases and then declinesas the amount of fishing increases.

Page 4: Biomass From an Ecosystem Based Fisheries Management ... Pope_MAREFRAME_… · SSB cod SSB haddock SSB saithe SSB whiting SSB plaice*0.1 SSB sole SSB (N B Plaice scaled to improve

Note on tradeoffs

Page 5: Biomass From an Ecosystem Based Fisheries Management ... Pope_MAREFRAME_… · SSB cod SSB haddock SSB saithe SSB whiting SSB plaice*0.1 SSB sole SSB (N B Plaice scaled to improve

We need Spawning stock to spawn the nextgeneration

Picture of fish eggs From Cover of Fish Reproductive Biology, Wiley-Blackwell

Page 6: Biomass From an Ecosystem Based Fisheries Management ... Pope_MAREFRAME_… · SSB cod SSB haddock SSB saithe SSB whiting SSB plaice*0.1 SSB sole SSB (N B Plaice scaled to improve

Biomass Reference points(From ICES introduction to advice)

Bpa

Spawning Stock Biomass

Blim BMSY

Page 7: Biomass From an Ecosystem Based Fisheries Management ... Pope_MAREFRAME_… · SSB cod SSB haddock SSB saithe SSB whiting SSB plaice*0.1 SSB sole SSB (N B Plaice scaled to improve

But Big Fish Eat Little Fish.Moreover, Little Fish may eat the young of Big Fish

Page 8: Biomass From an Ecosystem Based Fisheries Management ... Pope_MAREFRAME_… · SSB cod SSB haddock SSB saithe SSB whiting SSB plaice*0.1 SSB sole SSB (N B Plaice scaled to improve

Contrasting Models with and without Predation

Page 9: Biomass From an Ecosystem Based Fisheries Management ... Pope_MAREFRAME_… · SSB cod SSB haddock SSB saithe SSB whiting SSB plaice*0.1 SSB sole SSB (N B Plaice scaled to improve

Multispecies concerns

SandeelSprat

GreyGurnard

Page 10: Biomass From an Ecosystem Based Fisheries Management ... Pope_MAREFRAME_… · SSB cod SSB haddock SSB saithe SSB whiting SSB plaice*0.1 SSB sole SSB (N B Plaice scaled to improve

To Help we have made aninteractive multispecies model ofthe North Sea suitable forstakeholders use.

We will beholding adecision makersworkshop usingthis in Brusselsin June.We hope someof you may beable to attend.

Page 11: Biomass From an Ecosystem Based Fisheries Management ... Pope_MAREFRAME_… · SSB cod SSB haddock SSB saithe SSB whiting SSB plaice*0.1 SSB sole SSB (N B Plaice scaled to improve

Main Points

It is very important to avoid spawning stocks becoming too lowSo avoid Blim.But big fish eat small fish.So Predation Mortality increases at high predator biomassHence MSY Biomass estimates may be unrealistically highFor the long term we need to start managing the whole ecosystem

rather than single stocks.For Ecosystem Based Fishery Management MSY is probably not a

sensible societal objective.

My Acknowledgements are due to DG RESEARCH for funding and toICES, MAREFRAME and to the North Sea andPelagic Advisory Councils for help, advice andencouragement.

Page 12: Biomass From an Ecosystem Based Fisheries Management ... Pope_MAREFRAME_… · SSB cod SSB haddock SSB saithe SSB whiting SSB plaice*0.1 SSB sole SSB (N B Plaice scaled to improve

The Remaining Slides are for discussion points

Page 13: Biomass From an Ecosystem Based Fisheries Management ... Pope_MAREFRAME_… · SSB cod SSB haddock SSB saithe SSB whiting SSB plaice*0.1 SSB sole SSB (N B Plaice scaled to improve

Results for North Sea Cod from ICES Website

Page 14: Biomass From an Ecosystem Based Fisheries Management ... Pope_MAREFRAME_… · SSB cod SSB haddock SSB saithe SSB whiting SSB plaice*0.1 SSB sole SSB (N B Plaice scaled to improve

Decline in Recruitment of the Newfoundland Cod

Page 15: Biomass From an Ecosystem Based Fisheries Management ... Pope_MAREFRAME_… · SSB cod SSB haddock SSB saithe SSB whiting SSB plaice*0.1 SSB sole SSB (N B Plaice scaled to improve

Demersal CFP Compliant criteria

0.00

0.10

0.20

0.30

0.40

0.50

0.60

Fcod F haddock F saithe F whiting F plaice F sole

Fishing Mortality Rate

BAU MMEY Solution MAX GVA Maximum value

Conservation MEY Pel MEY Dem SS Fmsy

0

50

100

150

200

250

300

350

400

SSB cod SSB haddock SSB saithe SSB whiting SSB plaice*0.1 SSB sole

SSB (NB Plaice scaled to improve contrast)

BAU MMEY Solution MAX GVA Maximum value

Conservation MEY Pel MEY Dem Blim

SS MSY Btrigger SS Bmsy*

Note These are all compared to the existing single species reference points. Itis possible that some future CFP might use Multispecies reference points.

Page 16: Biomass From an Ecosystem Based Fisheries Management ... Pope_MAREFRAME_… · SSB cod SSB haddock SSB saithe SSB whiting SSB plaice*0.1 SSB sole SSB (N B Plaice scaled to improve

NORTH SEA GREEN MODEL

Page 17: Biomass From an Ecosystem Based Fisheries Management ... Pope_MAREFRAME_… · SSB cod SSB haddock SSB saithe SSB whiting SSB plaice*0.1 SSB sole SSB (N B Plaice scaled to improve

Spawning Stock Biomass (SSB)and Total biomass