Suitability of Dry Bay, Southeastern Alaska as Rearing Habitat for JuvenileSalmon

摘要

Dry Bay is located at the terminus of the Alsek River, a large glacial riveroriginating in Canada and flowing to the Gulf of Alaska. The Alsek River was historically a major producer of chinook salmon (Oncorhynchus tshawytscha) in southeastern Alaska, but the stock is currently depressed even after decades of rebuilding efforts. The authors studied physical characteristics and juvenile salmon utilization of Dry Bay to determine whether rearing conditions in Dry Bay may limit production. Dry Bay provided poor rearing habitat for juvenile salmon. The water was mostly cold (<5 deg C) and turbid throughout summer. Little salt water intruded into Dry Bay from the Gulf of Alaska; at high tide it is a shallow, 80-km(squared) freshwater lagoon, and at low tide the impounded water flows out at 80-180 cm/s. Strong currents and sand substrate result in habitat instability and absence of large organic debris. The few juvenile salmon captured were in low-current refugees near the mouth. Neither zooplankton nor benthic prey were abundant Dry Bay.