Abundance estimation of schools using a fisheries sonar
Original version
This report is not to be cited without prior reference to the authorsAbstract
An attempt of abundance estimation of fish schooling close to surface using sonar was
conducted in Eastern North Sea - Skagerrak in September 1990. The method is based on
measurements of the school area by the Furuno CSH-70 sonar and purse seine capture of
schools to establish a school-area to school-biomass relationship. In the actual region, the
biomass of herring and mackerel was estimated to about 90 000 ton and 430 000 ton,
respectively. The accuracy of the method is discussed and improvements suggested.