Community Research and Development Information Service - CORDIS

Scientific advice generated from the project

The result 29273 is a series of recommendations that can be taken forward to monitor levels of biodiversity of different components of herring in the fisheries in the North Sea and into ICES Divisions IIIa and IIIb and the western Baltic. Other HERGEN results informed the decisions taken here and led to the conclusion that two different approaches were required to monitor biodiversity in the herring fisheries in the area of study.

Genetics showed little apparent structuring of the North Sea fished population but otolith microstructure allowed the Downs winter spawning component to be separated off and therefore monitored. It has been recommended that 100 samples (2500 fish) should be taken throughout the fishery (as well as through surveys) annually to determine proportions of Downs herring within the main body of the North Sea fishery and therefore inform the assessment and management process. In IIIa, b, and western Baltic a combination of molecular genetic techniques and otolith microstructure gave the most cost effective method for determining mixtures of components within the fishery and therefore for monitoring biodiversity.

Until now, spring spawning components in the fishery had been unable to be determined beyond "western Baltic spring spawners" when it was thought highly likely that there were other spring spawning components within the area. It has been recommended that 30 samples (3000 fish) should be taken throughout the fishery annually to determine relative proportions. This project therefore provides methodology enabling their discrimination and provides the recommendation for the levels of sampling required for monitoring of the proportions of the various components.

Reported by

FRS MARINE LABORATORY
PO BOX 101, 375 VICTORIA ROAD
AB11 9DB ABERDEEN
United Kingdom
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