Action: Cease or prohibit midwater/semi-pelagic trawling
Key messagesRead our guidance on Key messages before continuing
- We found no studies that evaluated the effects of ceasing or prohibiting midwater/semi-pelagic trawling 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.
Many populations of subtidal benthic invertebrate species have declined or been depleted due to the multiple threats they are exposed to, including overharvesting (Hobday et al. 2000) and unintentional physical damage or catching during other fishing operations (Collie et al. 2000). Midwater/semi-pelagic trawling, which tows nets at depths higher in the water column (shallower) than bottom trawling, has in theory less impacts on the seabed and benthic invertebrates, as the gear should not come into contact with them. However, midwater trawls sometimes do come into contact with the seabed or with benthic invertebrates, particularly in areas with uneven topography and geological features, such as seamounts (Clark & Koslow 2007; He & Winder 2010). Therefore, ceasing or prohibiting midwater/pelagic trawling in an area can reduce or remove this pressure, and potentially benefit subtidal benthic invertebrate populations. Evidence for related interventions is summarised under “Threat: Biological resource use – Use a semi-pelagic trawl instead of demersal trawl”, and additional evidence related to ghost fishing from abandoned or lost gear is summarised under “Threat: Pollution - Use biodegradable panels in fishing pots” and “Recover lost fishing gear”.
Clark M.R. & Koslow J.A. (2007) Impacts of fisheries on seamounts. Seamounts: Ecology, Fisheries, and Conservation, 12, 413–441.
Collie J.S., Hall S.J., Kaiser M.J. & Poiner I.R. (2000) A quantitative analysis of fishing impacts on shelf‐sea benthos. Journal of Animal Ecology, 69, 785–798.
He P. & Winger P.D. (2010) Effect of Trawling on the Seabed and Mitigation Measures to Reduce Impact. Pages 295–314 in: P. He (Ed.) Behavior of Marine Fishes.
Hobday A.J., Tegner M.J. & Haaker P.L. (2000) Over-exploitation of a broadcast spawning marine invertebrate: decline of the white abalone. Reviews in Fish Biology and Fisheries, 10, 493–514.