Fig. 4

Light-based latitude estimates (upper panels) and daily maximum depth profiles (lower panels) during 2008 and 2009 for: a, b two Pacific halibut (Hippoglossus stenolepis) tagged with pop-up archival transmitting tags in the far-western Gulf of Alaska, and; c one Pacific halibut tagged at the Pribilof Islands in the eastern Bering Sea, from date of tagging (top of upper panels) to date of final tag reporting (bottom of upper panels). All data were obtained via satellite transmission (i.e., the tags were not recovered). The approximate longitudinal span of International Pacific Halibut Commission regulatory areas is indicated by shading. All three fish moved to deep water during the winter and returned to shallow water in spring. Eastward seasonal emigration is clearly evident in a and b. The fish depicted in c is known to have emigrated from its tagging area on the basis of its mid-winter depths (i.e., no such depths occur at the Pribilof Islands), but neither the timing or magnitude of its emigration can be determined. Longitude estimates are absent during its deep-water phase; the remainder of the profile is characterized by apparent measurement error of 5–7° relative to the fish’s known endpoint positions