Measurement of net-relative flow during a bottom trawl survey

The ecosystems surveys branch of the Northeast Fisheries Science Center of the National Oceanic and Atmospheric Administration (NOAA) is engaged in an ongoing effort to more fully characterize and understand the behavior of trawl nets while they are being fished. Survey results are critical inputs to population dynamics models of the northeast fishery. The models, in turn, contribute to the setting of fishery policy and strongly influence the local economy. During cruises in February and March of 2004 we mounted a MAVS-3 acoustic current meter on the head rope of a bottom trawl net and recorded the net-relative flow, attitude, and heading. Observations from the March cruise on NOAA fisheries research vessel Delaware II are reported here. The measurements show strong dynamic variations in the flow around the net that are directly forced by the motion of the vessel.