Movement and Habitat Use of Chinook Salmon Smolts and Two Predatory Fishes in Lake Washington and the Lake Washington Ship Canal. 2004-2005 Acoustic Tracking Studies

摘要

In Lake Washington and the Lake Washington Ship Canal (LWSC), basic data and information is needed regarding movement patterns and habitat use of federally-threatened Chinook salmon Oncorhynchus tshawytscha smolts and their predators in order to inform and guide management and restoration activities. Habitat use and movement patterns of juvenile ocean-type Chinook salmon in lake environments are poorly understood. In addition, Lake Washington and the LWSC are highly urbanized, altered, and managed, the consequences of which to Chinook salmon are not well known. The result is that resource managers are challenged to recommend and implement Chinook salmon conservation strategies in Lake Washington with few references to unaltered lacustrine habitats, and an incomplete understanding of how alterations to the Lake Washington ecosystem affect juvenile Chinook salmon. The main objectives of this study were to: 1) evaluate habitat use and movement patterns of Chinook salmon smolts during their outmigration in late-May, June, and July; and, 2) determine diel movement and habitat use of predators, including smallmouth bass and prickly sculpin, and evaluate spatial and temporal habitat overlap with Chinook salmon smolts. We used an HTI fine-scale acoustic tracking system to evaluate the behavior of Chinook salmon smolts (> 105 mm FL) and two predators, smallmouth bass Micropterus dolomieu and prickly sculpin Cottus asper, in Lake Washington and the LWSC during May-June, 2004-05. This system allowed us to continuously track fine-scale horizontal fish movements at specific study sites. Under ideal conditions, the precise location (up to - 1 m) of a tagged fish can be known every second it is in a tracking area. We tracked fish at four sites: Gene Coulon Park in south Lake Washington, the Seattle Tennis Club on the western shore of Lake Washington, and Portage Bay and north Lake Union (Gas Works Park) in the LWSC.