Commercial testing of a sorting grid to reduce catches of juvenile hake (Merluccius merluccius) in the western Mediterranean demersal trawl fishery
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Published source details
Sardà F., Bahamon N., Sardà-Palomera F. & Molí B. (2005) Commercial testing of a sorting grid to reduce catches of juvenile hake (Merluccius merluccius) in the western Mediterranean demersal trawl fishery. Aquatic Living Resources, 18, 87-91.
Published source details Sardà F., Bahamon N., Sardà-Palomera F. & Molí B. (2005) Commercial testing of a sorting grid to reduce catches of juvenile hake (Merluccius merluccius) in the western Mediterranean demersal trawl fishery. Aquatic Living Resources, 18, 87-91.
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 2003 of an inshore area in the western Mediterranean Sea, Spain (Sardà et al. 2005) reported that fitting an experimental size-sorting escape grid to a fish trawl net reduced the capture of unwanted, young hake Merluccius merluccius in the hake fishery, relative to the overall catch. Data were not tested for statistical significance. Hake under 21 cm were able to pass through the grid, and the maximum escape rates were for hake under 12 cm, relative to the retained catch not sorted out by the grid (data presented as length frequency distributions and selection curves). Average length at which 50% of hake were retained was 14.2 cm and for all size groups, the escapees accounted for 26% of the hake in weight. In addition, average size-selection range was high, indicating that grid performance was not yet at its best. Data was collected from 10 trawl deployments conducted on a commercial trawler in May 2003. Tow durations were 60–135 min, 3.7 knots and at 40–160 m depths. The trawl net was fitted with a hinged grid 145 x 100 cm, with 20 mm bar spacing in the lower part and four large open rectangles in the top half for larger fish to pass through. Two codends (40 mm mesh) connected to each half of the grid collected the small escaped fish (lower part) and target (large fish) retained (upper part) portions of the catch. Total length of all hake was measured.
(Summarised by: Chris Barrett)
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