Using a double codend to reduce discard mortality

Published source details Broadhurst M.K., Millar R.B. & Uhlmann S.S. (2009) Using a double codend to reduce discard mortality. ICES Journal of Marine Science, 66, 2077-2081.
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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 2007 of an area of seabed in an estuary flowing into the Tasman Sea, Australia (Broadhurst et al. 2009) found that modifying a prawn trawl by separating the codend into two compartments (double codend) did not reduce the catches of discarded finfish, compared to a conventional single codend. Average catch weights of discarded finfish species were similar for double and single codend trawls (double: 0.9 kg, single: 1.0 kg). In addition, average retained and discarded weights of the target school prawn Metapenaeus macleayi were both similar between codend types (double: 0.7–9.3 kg, single: 0.8–9.5 kg). In October 2007, a total of 24 trawl deployments (1 h) were done on a prawn fishing ground in Lake Wooloweyah, Clarence River estuary, New South Wales. Two codend types were tested: one modified with two compartments (12 hauls), and one with a single codend (12 hauls). Both codend types were square mesh (27 mm) and had a size-sorting escape grid (see original paper for gear specifications).

(Summarised by: Khatija Alliji)