Measuring the height of the fishing line and its effect on shrimp catch and bycatch in an ocean shrimp (Pandalus jordani) trawl

Published source details Hannah R.W. & Jones S.A. (2003) Measuring the height of the fishing line and its effect on shrimp catch and bycatch in an ocean shrimp (Pandalus jordani) trawl. Fisheries Research, 60, 427-438.
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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 of an area of seabed in the Pacific Ocean off the coast of Oregon, USA (Hannah & Jones 2003) found that modifications to the configuration of a shrimp trawl (to alter the height of the fishing line/footrope) resulted in reduced catches of unwanted small flatfish (Pleuronectiformes) and immature rockfish Sebastes spp. with increasing height of the fishing line. Catches of flatfish and rockfish between trawls with the same or higher fishing line height relative to the standard, were lower for two of two modified configurations (higher: 2–64 fish, standard: 4–81 fish). Conversely, catch numbers of both flatfish and rockfish increased in two of three trawl configurations with lower fishing line heights relative to the standard height (lower: 31–147 fish, standard: 2–50 fish), but were not significantly different in the other (lower height: 4–285 fish, standard height: 5–156 fish). Data were collected from 26 paired trawl deployments on a twin-rigged (dual net) commercial shrimp vessel fishing out of Newport. One side of the trawl was fished with a ‘standard’ configuration in which the central ‘drop’ chains between the fishing line and groundline were shortened to 51 cm. Four different configurations of drop chains were tested against the standard, each either increasing or decreasing the height of the fishing line (see original paper for full gear specifications). Five sets of comparative hauls were carried out (4–6 of each comparison). Codend catches were weighed and counted by species. The study does not report when the sampling took place.

(Summarised by: Natasha Taylor)