A method to estimate the annual larval production of the Norwegian spring-spawning herring (Clupea harengus L.)

A comprehensive survey in the larval distribution area of Norwegian spring-spawning herring along the Norwegian west coast was carried out annually by the Institute of Marine Research, Bergen in the years 1986-1990. Moreover, two small subareas were sampled repeatedly (usually twice a week) off Sunnmøre and at Buagrunnen throughout the hatching period each year. The daily larval production was worked out with the data obtained from the comprehensive survey covering the entire larval distribution area. Data obtained in the subareas had been used to construction the hatching curve so as to get the daily larval production percentage in the hatching period. Then, the annual larval productions were estimated