1. 1 1 Buoyancy of eggs of Norwegian coastal cod from four locations along the coast Erling Kåre Stenevik and Svein Sundby

2. 2 2 Objectives Measure the neutral buoyancy of coastal cod eggs from different locations Relate this to ambient salinity structure Model the vertical distribution of the eggs

3. 3 3 Sampling locations for parent fish

4. 4 4 Methods Broodstock collected during the spawning season in 2002 (2003) 40 families Buoyancy experiments conducted in spring 2004 Porsanger (3 families) Tysfjord (8 families) Helgeland (4 families) Øygarden (4 families) Density gradient column used for buoyancy measurements

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6. 6 6

7. 7 7 Salinity of neutral buoyancy PorsangerTysfjordHelgelandØygarden

8. 8 8 Porsanger Buoyancy Ambient salinity

9. 9 9 Tysfjord Ambient salinity Buoyancy

10. 10 Helgeland Ambient salinity Buoyancy

11. 11 Øygarden Ambient salinity Buoyancy

12. 12 Modelled vertical distribution

13. 13 Conclusions Differences in buoyancy and modelled vertical distribution of eggs from the four locations were found Eggs from Porsanger were on average lightest and distributed close to the surface Eggs from Tysfjord were on average heaviest with peak concentration at 50 m.

14. 14 So what?

15. 15 Vikebø et al. (in prep.)