Refining a Nordmøre-grid for a Brazilian artisanal penaeid-trawl fishery

Published source details Silva C.N.S., Broadhurst M.K., Schwingel A., Dias J.H., Cattani A.P. & Spach H.L. (2011) Refining a Nordmøre-grid for a Brazilian artisanal penaeid-trawl fishery. Fisheries Research, 109, 168-178.
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This study is summarised as evidence for the following.

	Action	Category
	Fit a size-sorting escape grid (rigid or flexible) to a prawn/shrimp trawl net Action Link

Fit a size-sorting escape grid (rigid or flexible) to a prawn/shrimp trawl net

A replicated, paired, controlled study in 2007–2009 of a seabed area in the southern Atlantic Ocean, Brazil (Silva et al. 2011) found that only one of four designs of rigid size-sorting escape grids (Nordmøre grid) fitted to shrimp/prawn nets reduced the amount of unwanted fish catch in an artisanal canoe-trawl fishery, compared to nets without a grid. Average weight of unwanted fish catch was reduced by 50% in nets fitted with a small grid compared to no grid (with: 1.2 kg/tow, without: 2.5 kg/tow) but was similar for three other larger grid designs (with: 1.0–1.2 kg/tow, without: 1.5 kg/tow). Catch of the target species Atlantic seabob Xiphopenaeus kroyeri was similar for four of four grid designs (with: 1.7–3.9 kg/tow, without: 0.9–4.5 kg/tow). Two trials were done between July 2007 and November 2009 off the coast of Paraná. A total of 18 (small grid, 60 min tows) and 12 (three large grids, 30 min tows) paired deployments of two trawl nets, one with a grid and one without, were done from a motorized canoe. Four configurations of aluminium grids (Nordmøre) were tested; all with 24 mm bar spacing, but differing in size/weight (one small, three larger), bar type, presence or absence of a guiding panel and mesh size of the extension piece of netting (see paper for specifications). Trawl nets were randomly deployed on each side of the canoe. Codend catches were separated by species and the numbers and weights of fish recorded.

(Summarised by: Leo Clarke)