Investigations on herring, Clupea harengus L., from the Norwegian Skagerak Coast during the years 1963-64

Abstract

1) The material was collected on a little part of the Norwegian Skagerak coast in 1963-1964. 2) The following data were sampled: total length and weight, stage and weight of gonads, intestinal fat content, vertebrae number and scales. Otoliths were taken from the last 5 samples. 3) Most of the herring examined appeared to be Skagerak spring spawners with a mean vertebrae number of about 57. Some of the herring with one and two winter rings were autumn spawners, belonging to either the North Sea autumn spawners or the Kattegat autumn spawners. 4) The otoliths of the Skagerak spring spawners had an opaque or a little hyaline nucleus with varying size of the central field. Some of the otoliths in the autumn spawners resemble otoliths previously found in the North Sea. 5) The Skagerak spring spawners had a rapid growth the first three years, and were spawning for the first time at three years age. 6) The maturity and the intestinal fat cycles appeared to be inversed.