The Behaviour of Cod When Approaching and Entering a

Pelagic Trawl

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

Research Question:

How do cod react to approach and passage of pelagic trawl?

Applications:

•Fishing strategy for efficient capture•Net design for efficient capture•Design and placement of selectivity devices

Tracking Distinct Schools of Cod From Vessel to Extension of Net

Fish pass under vessel13:31:52

536 m in 328 sec 167 m in 105 sec

School in extension of net13:39:05

Same school enters mouth of net13:37:20

1.6 m/sec

Measured velocity through water:

1.6 m/sec

1.6 m/sec

Calculations of Swimming Speed

sec

m 1.6

sec

m 1.6

WaterThrough Speed Trawl Time

Covered Distance Speed Swimming

sec

m 0

Cod in pelagic trawls do not appear to exhibit horizontal swimming behaviour!

Acknowledgements

The Fishery and Aquaculture Industry Research Fund