Fisheries Research Articles

Document Type

Article

Publication Date

10-18-2018

Journal Title

Proceedings of the National Academy of Sciences (PNAS)

ISSN

Print: 0027-8424 Electronic: 1091-6490

Keywords

fisheries, effort, footprint, habitat, seabed

Disciplines

Aquaculture and Fisheries

Abstract

Bottom trawlers land around 19 million tons of fish and invertebrates annually, almost one-quarter of wild marine landings. The extent of bottom trawling footprint (seabed area trawled at least once in a specified region and time period) is often contested but poorly described. We quantify footprints using high-resolution satellite vessel monitoring system (VMS) and logbook data on 24 continental shelves and slopes to 1,000-m depth over at least 2 years. Trawling footprint varied markedly among regions: from < 10 % of seabed area in Australian and New Zealand waters, the Aleutian Islands, East Bering Sea, South Chile, and Gulf of Alaska to > 50% in some European seas. Overall, 14 % of the 7.8 million-km2 study area was trawled, and 86% was not trawled. Trawling activity was aggregated; the most intensively trawled areas accounting for 90 % of activity comprised 77% of footprint on average. Regional swept area ratio (SAR; ratio of total swept area trawled annually to total area of region, a metric of trawling intensity) and footprint area were related, providing an approach to estimate regional trawling footprints when high-resolution spatial data are unavailable. If SAR was ≤ 0.1, as in 8 of 24 regions, there was > 95% probability that > 90 % of seabed was not trawled. If SAR was 7.9, equal to the highest SAR recorded, there was > 95 % probability that > 70 % of seabed was trawled. Footprints were smaller and SAR was ≤ 0.25 in regions where fishing rates consistently met international sustainability benchmarks for fish stocks, implying collateral environmental benefits from sustainable fishing.

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Digital Object Identifier (DOI)

https://doi.org/10.1073/pnas.1802379115