Abstract. 
Migration patterns of the capelin a pelagic species of fish that migrates
far north into the Arctic ocean to feed and subsequently around Iceland to
spawn, have been simulated and compared with data, collected twice a year
over a 40 year period. New methods from dynamical systems theory and large
parallel computations permit simulations with sufficiently many fish to
predict the migration patterns and reproduce the data. The migrations turn
out to be very sensitive to the temperature distributions in the ocean and
given ocean currents and position of landmasses the temperature is the
sole control parameter. The availability of the data over such a long
period and the simulations permits a search of temperature changes in the
oceans that span decades.