Objectives and outline
Catches of herring in the Skagerrak, Kattegat and SW Baltic originate from several spawning populations. The most important catch components are autumn spawners from the North Sea and spring spawners from the SW Baltic. The biological assessments have been inaccurate for the spring spawning resources, mainly due to the failure to describe the migration patterns of the different herring stock components. As a consequence, effective management measures have not been implemented for the fisheries that catch spring spawning herring.
The primary goal of the project is to improve the resource assessment of spring-spawning herring from the SW Baltic by the introduction and standardisation of new scientific methods in routine sampling by national laboratories. These methods are based on the use of biomarkers to identify the temporal and spatial distribution of the different population components. Examples are analyses of otolith microstructure, otolith microchemistry, fatty acids, lipid contaminants, parasite infection and morphometrics of individual fishes. Tests of these methods indicate that biomarkers can be deployed successfully in order to separate stock components.
The project will be developed along three lines:
A/ Introduction of new techniques (Tasks 1-3).
Potential biomarkers will be evaluated for routine sampling of commercial catches and during research surveys. Priority will be given to biomarkers that identify the different geographical stock contributions to the spawning populations at the individual level. The necessary equipment and knowledge will be introduced to participating laboratories.
B/ Standardisation between national laboratories (Tasks 4-5).
Standard sampling protocols will be elaborated and recommended. Total international effort (combined national resources) of both market sampling and research surveys will be optimised by cost benefit analyses. Sampling design and effort will be considered and recommended. Standard techniques will be inter-calibrated between laboratories through workshops.
C/ Establishment of a common database (Task 6).
A common database on results from both traditional and new sampling data of herring will be established. The database will be made accessible to the ICES community and should form the basis for improved resource assessment of herring in the Skagerrak, Kattegat and SW Baltic.
