Mesh selectivity in the New South Wales demersal trap fishery

Published source details Stewart J. & Ferrell D.J. (2003) Mesh selectivity in the New South Wales demersal trap fishery. Fisheries Research, 59, 379-392.
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This study is summarised as evidence for the following.

	Action	Category
	Modify fishing trap/pot configuration Action Link

Modify fishing trap/pot configuration

A replicated, controlled study in 1999–2000 of three fished areas of seabed in the Tasman Sea off New South Wales, Australia (Stewart & Ferrell 2003) found that bottom traps modified with back panels of different and larger mesh type improved the size selectivity of the majority of fish species, compared to the standard commercial trap. For five of 10 species, the estimated size at which fish had a 50% chance of escape (selection size) was greater for modified traps than standard traps (modified: 21–35 cm, standard: 15–25 cm). For four species, the selection size in modified traps was 17–24 cm, whereas all individuals were predicted to be retained in standard traps (see paper for size ranges – reported as length frequency curves). All sizes of one species were retained in both modified and standard traps. See original paper for individual data by species. Data were collected on chartered commercial vessels commercial fishing grounds in three locations during March–October 1999. Deployments were made of three different fish traps, identical (all covered with 37 mm hexagonal wire mesh) except for their back panels: a modified back panel of 50 mm × 75 mm welded mesh (122 trap lifts), a standard back panel of 50 mm hexagonal wire mesh (129 trap lifts), and a smaller 37 mm hexagonal wire mesh to retain and sample all sizes (104 trap lifts). Traps were baited and left on the seabed for 24–72 hours. Fish lengths from the nose to the end of the backbone (fork length) were measured.

(Summarised by: Rosslyn McIntyre)