Influence of grid orientation and time of day on grid sorting in a small-meshed trawl fishery for Norway pout (Trisopterus esmarkii)
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Published source details
Eigaard O.R., Herrmann B. & Nielsen J.R. (2012) Influence of grid orientation and time of day on grid sorting in a small-meshed trawl fishery for Norway pout (Trisopterus esmarkii). Aquatic Living Resources, 25, 15-26.
Published source details Eigaard O.R., Herrmann B. & Nielsen J.R. (2012) Influence of grid orientation and time of day on grid sorting in a small-meshed trawl fishery for Norway pout (Trisopterus esmarkii). Aquatic Living Resources, 25, 15-26.
Actions
This study is summarised as evidence for the following.
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Fit a size-sorting escape grid (rigid or flexible) to a fish trawl net Action Link |
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Fit a size-sorting escape grid (rigid or flexible) to a fish trawl net
A replicated study in 2007 of a fished area of seabed in the North Sea off northeast Scotland, UK (Eigaard et al. 2012) reported that fish trawl nets fitted with a rigid size-sorting escape grid allowed high proportions of non-target haddock Melanogrammus aeglefinus and whiting Merlangius merlangus to escape and around half of all herring Clupea harengus in an industrial fishery for the smaller-sized species Norway pout Trisopterus esmarkii. Data were reported as percentage escapes and results were not tested for statistical significance. The percentage of haddock and whiting excluded from the trawl by the grid was 93–100% and 81–100% respectively. The percentage of herring that escaped capture was 40–62%. The effect was similar for trawls during the day or night, and for grids facing either forwards or backwards. Loss of target pout was 6–14%. In November/December 2007, data were collected from 14 trawl deployments done on two, nine-day fishing trials on the Fladen Ground, a traditional Norway pout fishing ground. A trawl net fitted with a 180 x 130 cm fibreglass grid with 23 mm bar spacing, mounted at 60° angle, and either facing forwards with a top escape opening (five tows) or backwards with a bottom escape opening (nine tows) was tested. A cover collected catch passing through the escape outlet. Trawls were towed for 8 h at 3.1 knots and 131–144 m depths.
(Summarised by: Leo Clarke)
