The condition of the herring larvae off Western Norway in the period 1985-87. [HELP 31]

Abstract

A herring larval sampling program has been carried out off Western Norway in the period 1985-1988. This paper deals with results from 1985- 1987. Larval growth and condition have been studied both with living and formaldehyd preserved material. A comparativ study of the gut content has been carried out between the three years. The larvae have been staged according to morphometric criteria, and the duration of the different stages has also been investigated. High abundance of larvae beyond the "critical stage" were found both in 1985 and 1987. The growth and gut analyses show that there had been good larval feeding conditions both these years. In1986 , however, there were found few larvae without yolksac. Both the study of growth and the examination of gut content show that the larvae were in worse condition. At the same time of development the larval population in 1985 was dominated by growing larvae with resorbed yolksac, and more than 50% of the larvae had started to develop the dorsal fin. In 1986, however, the larval population was dominated by newly hatched larvae, while the population in 1987 was dominated by larvae at the stage of yolksac resorbtion.