Impacts of trawl disturbance on benthic communities in different habitats

Bottom trawling causes widespread disturbance of sediments in shelf seas and can have a negative impact on benthic fauna. We conducted a large-scale assessment of bottom trawl fishing of benthic fauna in different habitats, using a theoretical size-based model.

Ecological impacts of trawling in different habitats

The Ecosystem Approach to Fisheries requires that managers take account of the environmental impacts of fishing. Bottom trawling causes widespread disturbance of sediments in shelf seas and can have a negative impact on benthic invertebrate fauna. We conducted a large-scale assessment of bottom trawl fishing of benthic fauna in different habitats, using a theoretical size-based model. The impacts of trawling were greatest in areas with low levels of natural disturbance, while the impact of trawling was small in areas with high rates of natural disturbance. For the North Sea the model predicted that the bottom trawl fleet reduced benthic biomass and production by 56% and 21% respectively, compared to an unfished situation. We demonstrate an effective approach for assessing the environmental consequences of fishery management action that can be used to inform management decision making as part of an EAF.

Area closures and effort controls are widely used fishery management tools. Our simulations demonstrated that closures of different sizes and in different locations could have positive or negative effects on benthic communities. Area closures in lightly fished areas coupled with effort reductions, are expected to minimise the effects of fishing on benthic communities in the context of an EAF.

We develop linked state and pressure indicators of the impact of bottom trawling on benthic communities. The indicators measures the proportion of the area where trawling frequency is sufficiently high to prevent reaching 90% of pristine values. The advantages of using the area affected by trawling as a pressure indicator are that it is conceptually easy to understand, responds quickly to changes in management action, can be implemented at a relevant scale for fisheries management and that the necessary effort distribution data are centrally collected.

Associated publications

Hiddink, J.G.; Johnson, A., Kingham, R.; Hinz, H. (2011)
Could our fisheries be more productive? Indirect negative effects of bottom trawl fisheries on fish condition. Journal of Applied Ecology, 48:1441-1449

Hinz, H., Murray, L.G., Lambert, G.I., Hiddink, J.G. and Kaiser, M.J. (2013)
Confidentiality over fishing effort data threatens science and management progress. Fish and Fisheries, 14, 110-117.

Jennings, S., Lee, J. and Hiddink, J. G. (2012).
Assessing fishery footprints and the tradeoffs between landings value, habitat sensitivity and fishing impacts to inform marine spatial planning and an ecosystem approach. ICES Journal of Marine Science, 69, 1053-1063. doi:10.1093/icesjms/fss050.

Lambert, G. I., Jennings, S., Hinz, H., Murray, L. G., Lael, P., Kaiser, M. J. and Hiddink, J. G. (2012)
A comparison of two techniques for the rapid assessment of marine habitat complexity. Methods in Ecology and Evolution. 4, 226-235.

Lambert, G.I., Jennings, S., Hiddink, J.G., Hintzen, N.T., Hinz, H., Kaiser, M.J. and Murray, L.G. (2012)
Implications of using alternate methods of Vessel Monitoring System (VMS) data analysis to describe fishing activities and impacts. ICES Journal of Marine Science, 69: 682-693. doi:10.1093/icesjms/fss018
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Lambert, G. I., Jennings, S., Kaiser, M. J., Hinz, H. and Hiddink, J. G. (2011)
Predicting the impact of fishing on epifaunal communities. Marine Ecology Progress Series 430: 71-86

Hiddink, J.G., Hutton, T., Jennings, S. and Kaiser, M.J. (2006)
Predicting the effects of area closures and fishing effort restrictions on the production, biomass, and species richness of benthic invertebrate communities. ICES Journal of Marine Science, 63, 822-830.
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Hiddink, J.G., Jennings, S. and Kaiser, M.J. (2006)
Recovery status as an indicator of the large scale ecological impact of bottom trawling. Ecosystems, 9, 1190-1199.

Hiddink, J.G., Jennings, S., Kaiser, M.J., Quelros, A.M., Duplisea, D.E. and Piet, G.J. (2006)
Cumulative impacts of seabed trawl disturbance on benthic biomass, production, and species richness in different habitats. Canadian Journal of Fisheries and Aquatic Sciences, 63, 721-736.
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Queiros, A.M., Hiddink, J.G., Hinz, H. and Kaiser, M.J. (2006)
The effects of chronic bottom trawling disturbance on biomass, production and size spectra of invertebrate infauna communities from different habitats. Journal of Experimental Marine Biology and Ecology, 335, 91-103.
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Tillin, H.M., Hiddink, J.G., Jennings, S. and Kaiser, M.J. (2006)
Chronic bottom trawling alters the functional composition of benthic invertebrate communities on a sea basin scale. Marine Ecology Progress Series, 318, 31-45.
Data on biological traits of benthos can be downloaded from www.marlin.ac.uk/biotic
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