Meeting Abstract

48.8  Sunday, Jan. 5 11:45  Natal Homing and the Geomagnetic Imprinting Hypothesis for Salmon and Sea Turtles LOHMANN, K.J.**; PUTMAN, N.F.; LOHMANN, C.M.F.; Univ. of North Carolina, Chapel Hill; Oregon State University; University of North Carolina, Chapel Hill KLohmann@email.unc.edu

Several marine animals, including salmon and sea turtles, migrate across vast expanses of seemingly featureless ocean before returning as adults to their natal areas to reproduce. How animals accomplish these feats of natal homing has remained an enduring mystery. Accumulating evidence, however, supports the idea that such animals imprint on the magnetic field of their natal area and then use magnetic map information to guide themselves to their destination. Evidence for geomagnetic imprinting has been obtained in sockeye salmon from the Fraser River, which must detour around Vancouver Island to approach the river through either a northern or southern passageway. Recent analyses indicate that the proportion of salmon using each route is correlated with geomagnetic field drift: the more the field at a passage entrance diverges from the field at the river mouth, the fewer fish use the passage. Evidence for the use of magnetic maps during migration has been obtained in sea turtles, which use two magnetic field elements (inclination and intensity) that vary predictably across the globe and endow different geographic areas with unique magnetic signatures. When turtles are presented with particular magnetic signatures from their migratory route, they typically swim in directions that allow them to progress along their path. The ability to derive positional information from Earth’s magnetic field thus appears to play a central role in salmon and sea turtle navigation. Similar navigational systems may be widespread among diverse long-distance ocean migrants.