Estimating bottom trawling pressure and inferring relative benthic status in Taiwan’s EEZ when benthic data are limited
Lee, Y.-J.; Hilborn, R. (2026). Estimating bottom trawling pressure and inferring relative benthic status in Taiwan’s EEZ when benthic data are limited. ICES J. Mar. Sci./J. Cons. int. Explor. Mer 83(7): fsag136. https://dx.doi.org/10.1093/icesjms/fsag136
In: ICES Journal of Marine Science. Academic Press: London. ISSN 1054-3139; e-ISSN 1095-9289, more
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| Author keywords |
seabed habitats, trawl footprints, fishing impacts, benthic invertebrates, ecological risk assessment |
| Abstract |
Bottom trawling is one of the most widespread human disturbances to the seabed. Although trawl fisheries are intense in the waters surrounding Taiwan, their benthic impacts have yet to be quantified. To address this gap under data-limited conditions, this study combined two vessel tracking data sources from 2013 to 2023 to estimate the spatial distribution of annual average swept area ratio (SAR) and to infer relative benthic status (RBS) from trawling pressure within Taiwan’s Exclusive Economic Zone shallower than 1000 m. RBS was inferred using globally synthesized depletion and recovery parameters for benthic invertebrates, together with localized gear width and sedimentary habitat data. Mean annual SAR was 6.24 and the median was 1.34, indicating highly heterogeneous trawling intensity concentrated in sand and muddy-sand habitats. The mean RBS across the study area was 0.85, with a median of 0.99. Areas with relatively lower RBS were mainly distributed in nearshore waters dominated by domestic trawling and near the EEZ boundary where both Taiwanese and foreign vessels operated, suggesting higher cumulative trawling pressure in these areas. Given limited local benthic data, assumptions on taxon distribution across habitats and on impact parameters were required. Sensitivity analyses showed that mean RBS ranged from 0.73 to 0.90 under extreme habitat preference and trawling impact scenarios, indicating the range of variation in inferred status under these assumptions. This study is the first in East Asia to infer RBS by combining spatially explicit trawling pressure with ecological parameters, filling a gap in global trawl impact maps and providing critical baseline science for ecosystem-based fisheries management in Taiwan under data-limited conditions. |
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