Identification of Norwegian spring spawning herring larvae from spawning grounds off western Norway applying otolith microstructure analysis
Stenevik, E.K.; Fossum, P.; Johannessen, A.; Folkvord, A.
Sarsia 80(4): 285-292
1996
ISSN/ISBN: 0036-4827 Accession: 031777567
After the stock collapse in the 1960s the main spawning grounds of Norwegian spring spawning herring have been located off the More coast (northern grounds) and after 1989 spawning has also occurred at previous important grounds off the south-western coast of Norway (southern grounds). An overall objective of this study is to identify offspring from the different main spawning grounds in their nursery areas several months later. This requires criteria for identification of larval components from the main hatching areas. Peak hatching time at the two main spawning areas differ by approximately one month, being earlier at the northern spawning grounds. Passive drift from the southernmost areas adds another 2-3 months to this time difference until the larvae from the southern spawning grounds reach the spawning grounds off More. Otolith microstructure analysis of larvae collected along the drift path of the separate larval populations are used to trace past growth patterns. The results show a significant difference in back calculated increment width at age and in back calculated hatching distribution, and indicate that otolith microstructure can be used to separate components of offspring from the two spawning grounds.