Trawl exposure and protection of seabed fauna at large spatial scales

Abstract

Sustaining seabed fauna is critically important for marine ecosystem processes. We provide the most extensive assessment of the current trawl fishing exposure of benthic invertebrates across Australia?s wa-ters. This work responds to the global need to quantify and address the broad scale impacts of trawling on the seabed. We aimed to quantify trawl exposure and protection of benthic invertebrates at large-scales, including developing a method that integrates data from disparate seabed surveys to spatially expand predicted distributions. We incorporate data from 18 seabed surveys to map the abundance distribution of benthic invertebrates in 9 regions within Australia?s Exclusive Economic Zone. Our approach combines disparate benthic surveys and uses Random forests to predict taxa group distributions from environmental variables. Exposure and protection are quantified by overlapping predicted abundance distributions of benthic invertebrate groups with maps of trawl-footprint, marine reserves and fishery closures. We found that more of Australia?s EEZ is currently protected from trawling (58%) than exposed (<5%). Across all regions, 96% of benthic invertebrate groups had greater abundance protected than ex-posed to trawling. The mean exposure of benthic invertebrate abundance to trawling was 7%, compared to mean protection of 38% -further, 55% was neither exposed nor protected. This study is widely applicable elsewhere and for a range of other taxa, helping decision makers: identify taxa and regions that are at higher risk of disturbance, determine the effectiveness of current protection measures,and guide the placement of future protection measures. Such analyses can help managers achieve more sustainable marine ecosystems.