Publication Abstract

Determination of plaice lifetime movements in the North Sea by linking natural and electronic data records

Determination of plaice lifetime movements in the North Sea by linking natural and electronic data records

E. Hunter and A. Darnaude

The aim of this study is to describe the lifetime movements of plaice, Pleuronectes platessa L., in the North Sea, by linking the geographical movements recorded by fish tagged with electronic data storage tags (DSTs) to chemical signals simultaneously laid down in the ear-stones (otoliths) of the same fish. By linking these state of the art techniques, we aim to provide information on the population dynamics of North Sea plaice, which would be otherwise unattainable using conventional methods.

DSTs allow continuous records to be made of ambient conditions experienced by free-swimming fish in their natural environment. To date, we have used tidal (depth) data to reconstruct the geographical movements of 165 free-swimming plaice from returned DSTs, for periods of up to two repeat migration seasons. Plaice independently record ambient conditions throughout their lifetime by the accretion of calcium carbonate on the otoliths. Recent studies have demonstrated how the chemical composition of the otoliths may reflect the environmental history of individual fish. Matching the DST data with age markings on the otoliths may allow the retrospective positioning of fish in space and time throughout their lifetimes.

We aim to compare the reconstructed movements of around 80 DST-tagged plaice with the chemical signatures laid down simultaneously in the otoliths, in order to characterise annual migration routes. Although in its early stages, this work may for the first time allow interpretation of the migration history of plaice prior to tagging, and determination of the time and source of recruitment, thereby linking studies of pre- and post recruitment fish behaviour. In terms of exploitation, the results from this study have the potential to improve the parameterisation of assessment methods currently applied in fisheries management, and will therefore feed directly into management advice designed to promote sustainability.

Reference:

E. Hunter and A. Darnaude. 2004. Determination of plaice lifetime movements in the North Sea by linking natural and electronic data records. ICES ASR Vigo, Spain

E. Hunter* and A. Darnaude

ICES ASR Vigo, Spain, 2004