DIFFERENCES IN OTOLITH MICROSTRUCTURE AND BODY GROWTH-RATE OF NORTH-SEA HERRING (CLUPEA-HARENGUS L) LARVAE IN THE PERIOD 1987-1989

Autumn-spawned herring larvae originating either from the North Sea or from the Skagerrak were sampled during 1987, 1988 and 1989 and examined for otolith microstructure. The distance from the nucleus to the first increment (hatch check) in the otoliths did not vary due to their origin. The increment size, however, varied within the first 50 increments, with narrow increments (- 1 pm) in the northern areas and coastal central North Sea and wider increments (- 1.3 pm) offshore in the central North Sea and in the Dogger Bank area. The widest increment (> 2.5 pm) was found east of the Dogger Bank and in the Skagerrak area (1.7-1.8 pm). The daily growth rate increased from the Shetland and Buchan areas in the north (0.20-0.26mm d-1; 0.1-5.0% d-1) to the south and south-east (0.29-0.37mm d-1; 56-8.0% d-1). The second highest growth rate (0.38mm d"‘; 7.1% d-1) was back-calculated for the Skagerrak area. © 1992 International Council for the Exploration of the Sea.