Pelagic Trawling for Cod, Haddock and Saithe in the Barents Sea

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Pelagic Trawling for Cod, Haddock and Saithe in
the Barents Sea
Shale Rosen, Terje Jörgensen and Arill
Engås Insitute of Marine Research Postboks 1870
Nordnes N-5817 Bergen Norway shale.rosen_at_imr.no
Nor-Fishing Technology Conference 2008 Trondheim,
Norway 11-12 August 2008
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Overview

• Glossary
• Introduction to project, objectives
• 1960s-1970s pelagic trawl fishery
• Why the renewed Interest?
• Data collection
• Catches
• Comparison with demersal trawl catches
• Conclusions
• Next steps

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Glossary

• Pelagic Trawl Midwater Trawl Flytetrål
• Demersal Trawl Bottom Trawl Bunntrål

Cod Torsk Gadus morhua
Haddock Hyse Melanogrammus aeglefinus
Saithe Sei Pollachius virens
Images Northeast Fishery Science Center
www.nefsc.noaa.gov
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Introduction to Project

• Test pelagic fishery for species typically caught
  in demersal trawls
• Research Topics
• Availability of cod, haddock, saithe to pelagic
  trawls
• Selectivity of pelagic trawls
• Behaviour as trawl approaches and once inside
• Development of pelagic trawl to target cod,
  haddock, saithe

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1960s-1970s Pelagic Trawl Fishery

• Spring fishery for cod and haddock off northern
  tip of Noway, late summer fishery for haddock
  farther offshore
• Closed 1979 due to reports of high bycatch of
  juveniles (higher than in demersal trawls)

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Why the Renewed Interest?

• Impacts of demersal trawls on seabed
• Reduce bycatch of highly demersal species (eg.
  flatfish)
• Reduce fuel consumption
• Sorting grids and larger mesh proven successful
  in other trawl fisheries

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Data Collection, Net and Sensors
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Data Collection (cont.)

• Distance between doors and height relative to
  headrope and footrope
• Amount of towing wire and tension
• Catch in grid cover, cod end, and cod end cover

grid cover
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Catch Locations and Vertical Distribution, Cod
April 2008 cruise, pelagic cod area
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Catches in Pelagic Trawl

• Total 175 tons

50 in just 3 hauls!
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Length Distributions of Catch

• Few undersized fish encountered, removed by
  sorting grid

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Length Distributions of Catch Comparison with
Demersal Trawl

• Larger cod captured in cod end of pelagic trawl

mean 81 cm 5 kg
mean 75 cm 4 kg
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Comparisons With Demersal Trawls
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Conclusions- Gear

• Opening of 40 m by 60 m was well-sized for the
  distributions and behaviour we encountered.
• Benthic trawl doors spread net adequately and
  made it easy to switch between pelagic and
  demersal trawls
• 300mm liner in belly may not be necessary (at
  most 9 fish meshed per haul)

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Conclusions- General

• In the right conditions, pelagic trawl is a
  highly effective way of catching cod (150 tons in
  5 days)
• Most effective during brightest daylight hours
• Sorting grid effectively removed small gadoids
  and pelagics (herring and blue whiting)
• Cod caught in pelagic trawl were larger than in
  demersal trawl
• CPUE higher in pelagic trawl than demersal trawl,
  when pelagic distributions were present
• Fuel consumption between that of single and twin
  demersal trawl
• Not a replacement for demersal trawls, but
  pelagic trawls may increase fleets flexibility
  and reduce seabed impact for each portion of
  quota caught without using demersal trawl

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Next Steps

• October cruise on R/V, focused on behaviour and
  selectivity studies
• Spring 2009 cruise on F/T, focused on use in
  commercial fishery
• Discussions with Fisheries Directorate about
  authorizing an experimental fishery with data
  collection
• We anticipate continued cooperation with net
  manufacturers and fishermen to refine design for
  selective and efficient pelagic trawls for gadoids

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Acknowledgements
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Questions?