Acoustic abundance estimation of the spawning component of the local herring stock in Lindaaspollene, western Norway

Abstract

During 1978-1980 yearly acoustic surveys were carried out in the spawning area of a small herring stock in the semi-enclosed bay area Lindaaspollene, approximately 30 km north of Bergen, using the Simrad EY-M echo sounder system. Absolute abundance estimates have been calculated by means of echo integration of the survey data and controlled acoustic measurements of anaesthetized single fish at tilt angles between -45° and 45°. The stock size may roughly be set at 150,000-250,000 individuals in 1979, while in 1980 the number was 100,000-200,000 older fish and 150,000-300,000 recruits.