Comparing and modifying penaeid beam and otter trawls to improve ecological efficiencies

Published source details McHugh M.J., Broadhurst M.K., Sterling D.J. & Millar R.B. (2014) Comparing and modifying penaeid beam and otter trawls to improve ecological efficiencies. Fisheries Management and Ecology, 21, 299-311
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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, controlled study in 2013 of an area of sand and mud bottom in an estuary off the Tasman Sea, Australia (McHugh et al. 2014) found that modifying the configuration (spreading mechanism) of prawn trawls resulted in reduced overall catches of unwanted fish in one of four configurations. Average catch rate of unwanted fish by number was lower in otter trawls without sweep wires (62 fish/40 min) than with (96 fish/40 min), and was similar to beam trawls both with and without a horizontal wire across the trawl mouth (with: 59 fish/40 min, without: 73 fish/40 min). Catches of target school prawn Metapenaeus macleayi were similar in otter trawls with and without sweep wires (with: 2,600, without: 2,100 ind/40 min), but lower in beam trawls with a horizontal wire (1,200 ind/40 min) than without (1,600 ind/40 min). In summer (austral) 2013, a total of 36 trawl deployments in Lake Wooloweyah estuary in New South Wales (at 1–2 m depth) were done with each of four trawl designs: an otter trawl, with and without sweep bridles, and a beam trawl with and without a horizontal wire. Sweep wires were removed to test reduction in the herding of fish into the net and the horizontal wire was designed to produce a fish escape response. Full details of the trawl specifications are provided in the original study.

(Summarised by: Leo Clarke)