Selectivity of diamond- and square-mesh codends in the deepwater crustacean trawl fishery off the Balearic Islands (western Mediterranean)

Published source details Guijarro B. & Massutí E. (2006) Selectivity of diamond- and square-mesh codends in the deepwater crustacean trawl fishery off the Balearic Islands (western Mediterranean). ICES Journal of Marine Science, 63, 52-67.
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This study is summarised as evidence for the following.

	Action	Category
	Use a square mesh instead of a diamond mesh codend in a trawl net Action Link

Use a square mesh instead of a diamond mesh codend in a trawl net

A replicated, controlled study in 2002–2003 of deep-water prawn fishing grounds in the Mediterranean Sea, Spain (Guijarro & Massuti 2006, same experimental set-up as Ordines et al. 2006) found that a square mesh codend reduced the amount of discarded fish catch, compared to a conventional diamond mesh codend. The proportion (by weight) of discarded non-commercial species was lower in the square mesh codend (3–11%, of which 80–93% were fish) compared to the diamond mesh codend (7–28%, of which 90–98% were fish), and was similarly decreased for discarded commercial species (square: 2–7%, of which 59–97% were fish; diamond: 7–17%, of which 45–99% were fish). In addition, no differences in commercial retained catch were found between mesh types and overall, the catch composition varied with depth and season. The total catch (weight) comprised fish (teleosts 55%, elasmobranchs 14%), crustaceans (28%), and cephalopods (6%). Catch comparison data were collected by commercial bottom trawler on a main crustacean fishing ground between 251–737 m depths, south of Mallorca. A total of 19 bottom trawl deployments each of square and diamond mesh codends (both 40 mm mesh) were done in September-October 2002 (18 hauls) and May-June 2003 (20 hauls). Deployments were 4.5 h at 2.5 knots. A small mesh (20 mm) cover over the codends sampled the escaping catch. All fish were identified, counted, and length measured.

(Summarised by: Rosslyn McIntyre)