Bottom trawling is the most widespread human activity affecting seabed habitats. Assessment and effective management of the effects of bottom trawling at the scale of fisheries requires an understanding of differences in sensitivity of biota to trawling. Responses to disturbance are expected to depend on the life-history, and in particular, the intrinsic rate of increase of populations, which is expected to be linearly related to the reciprocal of longevity.
We examine the relationship between the longevity of benthic invertebrates and their response to trawling. We test whether longevity distributions of benthic communities can be used to predict their sensitivity to trawling impacts.
For biota with a life-span >1yr, the depletion caused by a single experimental trawl pass was ~9%. The effect of bottom trawling in comparative studies increased with longevity of the organism, with a 2-3 times larger effect on biota living >10yr than on biota living 1-3yr. This is because recovery after trawling takes a few years for short-lived organisms but can take more than 10 years for long-lived organisms.
The sensitivity of habitats to bottom trawling is, therefore, predicted to be higher in habitats harbouring higher proportions of long-lived organisms.
Where the longevity distribution of a community can be inferred, the parameters of depletion and recovery rates estimated here can be combined with high resolution maps of trawling intensity to assess and manage trawling impacts. The conservation status of ecosystems can be improved by avoiding bottom trawling in areas with a high abundance of long-lived biota.
Topics: Fisheries, aquaculture, and the oceans , Topics: Effective marine conservation planning
