date:Aug 14, 2012
Fishing records from anglers on 59 Norwegian rivers show that more and more salmon are staying out at sea for two or more winters - instead of one - before migrating back upriver to mate.
The trend, spotted by Leif Asbjrn Vllestad of the University of Oslo and colleagues, coincides with warming in the North Atlantic between 1991 and 2005.
Salmon need to eat enough in the autumn for their gonads to mature the following spring.
Temperature-driven changes in the food web mean fish may lack food