Abstract
For nets and trawls of high solidity, e.g. intended for harvesting marine zooplankton such as Calanus finmarchicus or krill, the filtration performance and towing resistance depend strongly on the design parameters and towing speed. In particular, the Reynolds number dependency may be dramatic for fine-meshed trawls compared to more traditional trawls, and care must be taken when assessing the flow conditions in such trawls, both theoretically and experimentally. Basic aspects of flow through trawls and net samplers have been reviewd and discussed, and a theoretical model for the flow through and the drag on nets and trawls of high solidity has been developed.