Validation and development of otolith microchemistry in free-ranging marine fish

Anna Lewis

University of Southampton

Supervisors: Dr Clive Trueman, University of Southampton; Dr Ewan Hunter, CEFAS

Abstract: The aim of the project is to determine the relationship between otolith microchemistry and the ambient environmental conditions experienced by free-swimming plaice (Pleuronectes platessa L.). By matching known spatial and temporal movements with otolith composition, we hope to validate and develop otolith microchemistry as a useful tool in marine fish spatial ecology, and will use the results to complete our understanding of the lifetime movements and stock structure of North Sea plaice.

Data records from free-ranging plaice tagged with electronic data storage tags (DSTs) will be used to provide an independent measure of location with which to compare trace element and stable isotope composition of concomitant otolith material. Also, the physical and chemical environments experienced during the plaice lifecycle will be analysed and used to construct predictive maps of otolith composition.

Otolith microchemistry provides a promising 'natural tag' with which to retrospectively track movements of wild fish, but it has yet to be applied widely to fully marine species. The project aims to provide in situ validation of this technique and produce predictive maps that could ultimately remove the need for extensive otolith reference collections for future studies in the North Sea. Also, the information on plaice spatial dynamics derived from this study will be considered both in terms of implications for current management strategies, and how data derived from otolith microchemistry might best be applied to marine fisheries management in the future.

Web: http://www.noc.soton.ac.uk/geochem/ | http://www.cefas.co.uk/

Plaice (Pleuronectes platessa L.) sagittal otolith (CEFAS)