Abstract
Bottom trawls impact the seafloor and benthic ecosystem. One of the direct physical impacts is the mobilization of sediment in the wake of trawl gear components that are in contact with or are close to the seabed. The quantity of sediment mobilized is related to the hydrodynamic drag of the gear components and the type of sediment over which they are trawled. Here we present a methodology to estimate the sediment mobilization from hydrodynamic drag. The hydrodynamic drag of individual gear components is estimated using empirical measurements of similarly shaped objects, including cylinders, cubes, and nets. The method is applied to beam trawls used in the Dutch North Sea flatfish fishery and validated using measurements of beam trawl drag from the literature. Netting contributes most to the hydrodynamic drag of pulse trawls, while the tickler chains and chain mat comprise most of the hydrodynamic drag of conventional beam trawls. Taking account of the silt content of the areas trawled and the number of different beam trawl types used by the fleet, sediment mobilization is estimated as 9.2 and 5.3 kg m−2 for conventional 12 m beam and pulse trawls, respectively, and 4.2 and 4.3 kg m−2 for conventional 4.5 m beam and pulse trawls.
| Original language | English |
|---|---|
| Article number | fsab029 |
| Pages (from-to) | 1574–1586 |
| Number of pages | 13 |
| Journal | ICES Journal of Marine Science |
| Volume | 78 |
| Issue number | 5 |
| Early online date | 7 Apr 2021 |
| DOIs | |
| Publication status | Published - 31 Aug 2021 |
Bibliographical note
AcknowledgementsA. Lokker (Cooperatie Westvoorn), H. Klein-Woolthuis (HFK engineering), A. van Wijk (van Wijk, BV), M. Drijver and a number of individual skippers are gratefully acknowledged for providing information on gear dimensions. We tank Niels T. Hintzen for providing an updated data set with swept area ratios by grid cell for conventional tickler chain and chain mat beam trawl.
Funding
This study was funded by the European Maritime and Fisheries Fund (EMFF) and the Netherlands Ministry of Agriculture Nature and Food Quality (LNV) (Grand/Award Number: 1300021172), the Netherlands Ministry of Agriculture Nature and
Food Quality (BO-code), the Belgian EMFF project “Benthisnationaal” and by the FP7-project BENTHIS (312088). The article does not necessarily reflect the views of the European Commission and does not anticipate the Commission’s future
policy in this area.
Keywords
- beam trawl
- benthic ecosystem
- chain mat
- electro trawls
- hydrodynamic
- drag
- pulse trawl
- tickler chains
- trawling impact
Access to Document
- Rijnsdorp_etal_ICESJMS_Sediment_Mobilization_By_VoR
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