Global warming is leading to warmer waters in the North Sea and is causing bottom-dwelling fish to see cooler waters by moving northward or to regions of deeper ocean (Inman, 2005). Two-thirds of the fish studied were on the move to different locations when records from 1977 to 2001 were analyzed. Ocean temperature at the sea floor rose by 1ºC over that period. Both commercial and non-commercial fish were included in the survey and both were observed to be migrating.
Reference
Inman, M., 2005: Fish moved by warming waters. Science, 308, 937.