Physics

The physical environment in which walleye pollock live varies on many scales. Decadal climate changes such as that noted during the late 1970's have profound effects on abundance; water properties fluctuate with a large-scale event such as El Niño's. On a smaller scale, larval survival may be determined by a single storm. Much of the variability in the circulation of the Gulf of Alaska results from global atmospheric phenomena which generate an annual cycle of storms traversing the region. The transport of water by the Alaskan Stream and the Alaska Coastal Current pulses with the passage of strong storms. A high, nearly continuous mountain chain along the Alaska Peninsula disrupts regional winds creating local accelerations over coastal waters. Frequent winter storms bring high amounts of precipitation to the coastal region, and the discharge of this stored precipitation affects the generation of eddies. A deep sea valley between the Kodiak Archipelago and the peninsula behaves as an estuary (surface flow southwest to the ocean and a deeper, subsurface counterflow). This estuarine-like flow in the sea valley has warmer, more saline water from the continental slope that enters on the southeastern side.