Action: Use more than one net on otter trawls
Key messagesRead our guidance on Key messages before continuing
- We found no studies that evaluated the effects of using more than one net on otter trawls on subtidal benthic invertebrate populations.
‘We found no studies’ means that we have not yet found any studies that have directly evaluated this intervention during our systematic journal and report searches. Therefore, we have no evidence to indicate whether or not the intervention has any desirable or harmful effects.
Trawling is a method of fishing that involves pulling a fishing net (trawl) through the water behind one or more boats. Otter trawls have a pair of boards or metal plates (otter boards) which attach to the sides of the net and keep the net open as it is pulled through the water. More than one trawl can be towed simultaneously from the same boat. Towing three trawls behind one boat has been found to retain a lower weight of unwanted fish compared to a single rig in a river in Australia (Broadhurst et al. 2013a). Single and triple rigs have fewer otter boards than double or quad rigs and, therefore, less contact with the seabed, which may have less impact on subtidal benthic invertebrates (Broadhurst et al. 2013a). A study in that same Australian river found that there was no difference in the numbers or weight of unwanted fish caught between a double rig (with four otter boards) and a dual rig (with two otter boards) (Broadhurst et al. 2013b).
Evidence for other interventions related to otter trawl is summarised under “Threat: Biological resource use – Use an otter trawl instead of a beam trawl”, and “Use an otter trawl instead of a dredge”. Evidence for other interventions related to using different fishing gear is summarised under “Threat: Biological resource use”.
Broadhurst M.K., Sterling D.J. & Millar R.B. (2013a) Progressing more environmentally benign penaeid-trawling systems by comparing Australian single- and multi-net configurations. Fisheries Research, 146, 7–17.
Broadhurst M.K., Sterling D.J. & Millar R.B. (2013b) Relative engineering and catching performances of paired penaeid-trawling systems. Fisheries Research, 143, 143–152.