A method to geolocate eastern Baltic cod by using Data Storage Tags (DSTs)

DSTs can be used to investigate horizontal and vertical migrations in relation to the spawning and feeding grounds, and to estimate rates of migration and dispersion for different localities and seasons, for example with respect to hydrographic features. Our aim here is to present a new geolocation methodology which will be used to reconstruct migration pathways of individual eastern Baltic cod. The method is based on combined data of pressure, temperature and salinity obtained by DSTs attached to cod with a length greater than 45 cm. Hydrographic fields obtained from hydrodynamic modeling are used as a geolocation database in order to identify individual tracks of Baltic cod by comparison with the environmental data collected by each DST. A state-space Kalman filter was used to estimate geolocation errors, movement parameters, and most probable tracks from the derived locations. We present migration routes of 9 selected tagged cod released in the Bornholm Basin of the Baltic Sea in early spring 2003.

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