Increasing lateral mesh openings in penaeid trawls to improve selection and reduce drag

Published source details Broadhurst M.K., Sterling D.J. & Millar R.B. (2015) Increasing lateral mesh openings in penaeid trawls to improve selection and reduce drag. Fisheries Research, 170, 68-75.
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This study is summarised as evidence for the following.

	Action	Category
	Modify the design or configuration of trawl gear (mixed measures) Action Link

Modify the design or configuration of trawl gear (mixed measures)

A replicated, paired, controlled study in 2013–2014 of an area of sand and mud bottom in the Clarence River estuary, Tasman Sea, Australia (Broadhurst et al. 2015) found that modifying a prawn trawl design (wing mesh orientation and hanging ratio) typically reduced the overall catches of unwanted fish by number, but not by weight, compared to a conventional design. Overall catch numbers of unwanted fish were reduced in three of the four modified trawls compared to the conventional trawl (diamond mesh wings, both loose and tight: 35 fish/ha, loose square mesh: 37 fish/ha, conventional: 55 fish/ha), but were similar in the tight square mesh trawl (40 fish/ha). By weight, catch rate of all non-target fish species was reduced only with loose diamond wings (0.7 kg/ha) compared to the conventional trawl (1.1 kg/ha), and was similar between the other three designs and the conventional trawl (0.8 kg/ha). In (austral) summer 2013/2014, four novel trawl configurations (35 mm diamond or square mesh wing/side panels, and loose or tight hanging ratios) were tested against a conventional trawl with 41 mm diamond mesh wings. Twenty-four deployments of each trawl design were conducted on a twin-rigged trawler, paired with another design. All trawls also had a size-sorting escape grid. Full trawl details are provided in the original paper.

(Summarised by: Leo Clarke)