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Ecological Impact of North Sea Hake: Implications for Fisheries Management

Explore the rise of North Sea hake, its distribution, stock assessment, landings, and implications for fisheries. Learn about hake populations, spawning areas, and the need for sustainable management practices.

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Ecological Impact of North Sea Hake: 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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