2009 groundfish trawl video (Observation and quantification of herding behavior in groundfishes in relation to the sweeps of the Aberdeen trawl used in the NWFSC bottom trawl survey)

The possible herding of flatfish during survey trawl operations was the subject of much discussion among the stakeholders in the petrale sole fishery during the 2009 stock assessment review and subsequent decision making by the Pacific Fishery Management Council (PFMC). These discussions focused on the high estimates of survey catchability in the 2009 petrale sole stock assessment. The survey catchability, or q, is the scalar that relates the magnitude of the survey index to the predicted size of the population. The estimate of q was high in the petrale sole assessment because the magnitude of the relative index of abundance from the NWFSC survey is larger than the population estimates from the stock assessment model. The main focus of this project is to determine if the sweeps, or the cable gear running between the trawl doors and the wings of the net, on the survey trawls are herding fish into the net, resulting in a larger effective area swept than what was calculated using the distance between the wings. Work was done by 5 FTEs and 1 contractor, involving deploying cameras and lights on survey trawl for video observation of fish behavior near sweeps. Management audience is the PFMC. Project was one-time, and part of 2009 bottom trawl survey. Pilot study videos of NWFSC groundfish trawl and flatfish behavior.