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The rise of North Sea hake: ecological impact and implications for fisheries management

The rise of North Sea hake: ecological impact and implications for fisheries management. Alan Baudron 1 , Doug Speirs 2 , Mike Heath 2 , Chris McCaig 2 , Paul Fernandes 1. 1 University of Aberdeen 2 Strathclyde University. Spawning areas. Merluccius merluccius

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The rise of North Sea hake: ecological impact and implications for fisheries management

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  1. The rise of North Sea hake: ecological impact and implications for fisheries management Alan Baudron1, Doug Speirs2, Mike Heath2,Chris McCaig2, Paul Fernandes1 1 University of Aberdeen 2Strathclyde University

  2. Spawning areas • Merlucciusmerluccius • Widely distributed: Mauritania to Norway • Spawning from February to July (ICES, 2012) • Little knowledge in northern areas European hake Distribution

  3. Northern hake stock • Northeast Atlantic: 2 large stock units • Northern hake stock from Spain to Norway • Assessment estimates for stock unit • 5 surveys: • North Sea (NS-IBTS): 1965-2012 • West of Scotland (SWC-IBTS): 1985-2011 • Ireland (IGFS): 2003-2008 • Porcupine bank (SP-PORC): 2001-2011 • Bay of Biscay (EVHOE): 1997-2010

  4. Mean density estimates • Large increase in density (x 4) in recent years, x 5 in North Sea • Huge difference between Q1 and Q3 in the North Sea

  5. Density (kg/km2)

  6. Estimates for North Sea hake • Northern hake survey biomass = mean density * area • qsurvey = Northern hake survey biomass / Northern hake assessment biomass • North Sea TSB = North Sea hake survey biomass * (1/qsurvey) • Length at 50% maturity (L50) • North Sea SSB = North Sea TSB > L50 • North Sea recruitment = number of age 1 individuals

  7. North Sea hake stock assessment • Biomass: increase by a factor 4 in quarter 1, a factor 8 in quarter 3 • Slight increase in recruitment

  8. North Sea hake landings • Large landings of North Sea hake in the 1950s • Sudden increase previously occurred in North Sea

  9. Quarter 1 North Sea hake length frequencies Quarter 3 • Difference between quarter 1 and quarter 3 • More large individuals at quarter 3 • Observation consistent through time

  10. UK hake catches (kg) 2005-2011

  11. Increase in North Sea hake: the consequences North Sea quota share (tons) • CFP: relative stability • 2010: 2941 tons of hake landed by Scottish vessels in the North Sea • CFP reform: discard ban • Hake “choke” species for North Sea demersal fisheries

  12. Conclusions • Increase in North Sea hake: WHY? • Fishing? Northern hake recovery plan since 2004 • Environment? Hake recruitment variability impacted by environmental conditions (Sánchez & Gil, 2000) • Something else? T°C • Are hake here to stay? • Situation different from the 1950s • North Sea temperature increase • Low cod biomass • Hake migrations • Temperature? Inflow? Prey? • Little knowledge about hake in North Sea (spawning/feeding areas?) • Implications for fisheries management • Relative stability • Quotas do not reflect the regional stock abundance

  13. Future work • Ecosystem model: FishSUMS (Speirset al., 2010) • Assess consequences of hake increase on NS ecosystem • Model North Sea fishery under different “hake scenarios”

  14. Ta! Funding:

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