Natural markers for the different spawning groups of cod in Icelandic waters, based on otolith elemental fingerprints and otolith shape. Ingibjörg G. Jónsdóttir University of Iceland Supervisors: Dr. Guðrún Marteinsdóttir Dr. Steven Campana

Cod stock in the North Atlantic Major demersal fish resourse Separate stocks in the North Atlantic Management Population structure

Spawning sites in Icelandic waters

Objectives The purpose of this project is to characterize each of the spawning groups in Icelandic waters, in terms of their otolith elemental fingerprint and otolith shape, for use as a natural tag or marker in tracking subsequent movements.

Sampling data collection: –100 cod / station –length –weight –sex and sex maturity –otoliths

Methods ۷Shape analysis –influenced by different growth rate –Fast Fourier Analysis Campana & Casselman 1993 ۷Elemental analysis –influenced by different chemical composition of the ocean –Trace elements: Ba, Mg, Li, Mn, Sr, Pb Phenotypic methods that give indirect basis for stock structure