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@imr.no

Nor-Fishing Technology Conference 2008

Trondheim, Norway 11-12 August 2008

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

GlossaryPelagic Trawl = Midwater Trawl = Flytetrål

Demersal Trawl = Bottom Trawl = Bunntrål

Cod = Torsk = Gadus morhua

Images Northeast Fishery Science Center www.nefsc.noaa.gov

Haddock = Hyse = Melanogrammus aeglefinus

Saithe = Sei = Pollachius virens

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

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)

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

Data Collection, Net and Sensors

262 meters

40 meters

60 meters 15 meters7 meters

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

cod end cover

cod end

Catch Locations and Vertical Distribution, Cod

April 2008 cruise,pelagic cod area

Catch by Time of Day, Cod

0

10

20

30

40

50

60

70

80

90

22:00-01:59

02:00-05:59

06:00-09:59

10:00-13:59

14:00-17:59

18:00-21:59

Time of day

Tota

l Cat

ch (t

ons)

Catch per Haul, Cod

0011111256

10

16

17

21

21

22

50

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1

Catch, tons

% o

f T

ota

l Ca

tch

Catches in Pelagic Trawl

Total: 175 tons

X X

50% in just 3 hauls!

Length Distributions, Haddock

0%

5%

10%

15%

35 40 45 50 55

Fish length (cm)

% o

f fi

sh

Codend

Grid Cover

Codend Cover

Length Distributions, Cod

0%

1%

2%

3%

4%

5%

45 55 65 75 85 95 105 115

Fish length (cm)

% o

f fi

sh

Codend

Grid Cover

Codend Cover

Length Distributions of CatchFew undersized fish encountered, removed by sorting grid

47 cm, Minimum Legal Size 42 cm, Minimum Legal Size

Length Distributions of Catch: Comparison with Demersal Trawl

Larger cod captured in cod end of pelagic trawl

mean75 cm = 4 kg

mean81 cm = 5 kg

Comparisons With Demersal Trawls

Image Injector Trawldoors A/S

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)

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 fleet’s flexibility and reduce seabed impact for each portion of quota caught without using demersal trawl

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

Acknowledgements

The Fishery and Aquaculture Industry Research Fund

Questions?