The role of geomorphic habitat type, drift cell scale, and geographic scale in defining fish use of nearshore habitats is poorly known, particularly for Pacific salmon and their prey. In this study, key areas of nears...The role of geomorphic habitat type, drift cell scale, and geographic scale in defining fish use of nearshore habitats is poorly known, particularly for Pacific salmon and their prey. In this study, key areas of nearshore habitat in central and western Strait of Juan de Fuca were categorized by geomorphic habitat type and assessed for fish use within a degraded （Elwha） and intact comparative drift cells over a one year period. Juvenile Chinook and coho salmon were also sampled for genetic analysis to define regional dispersal patterns. Key findings are： （1） Ecological function of the area＇s nearshore is complex, with very strong seasonal variation in fish use both within and across GMHT （geomorphic habitat type）; （2） GMHT link to nearshore function for fish use differs depending on the fish species and time of year. Surf smelt and sand lance were the most abundant. And they were seasonally used embayed, spit, and bluff shorelines more than lower rivers. Juvenile Chinook, coho, and chum salmon occurred in much lower density than forage fish species, and used lower rivers more than other GMHTs; （3） When GMHTs were combined and analyzed at the drift cell scale, the degraded drift cell had different ecological patterns than the intact drift cell; （4） Cross regional juvenile fish use of nearshore is an important component of habitat use： juvenile Chinook and coho from as far away as the Columbia River Oregon and Klamath River California utilize central Strait of Juan de Fuca shorelines. Forage fish species may do so as well. Drift cell and cross regional scales are therefore most important for accurately defining nearshore ecological function, management, and restoration actions.展开更多
文摘The role of geomorphic habitat type, drift cell scale, and geographic scale in defining fish use of nearshore habitats is poorly known, particularly for Pacific salmon and their prey. In this study, key areas of nearshore habitat in central and western Strait of Juan de Fuca were categorized by geomorphic habitat type and assessed for fish use within a degraded （Elwha） and intact comparative drift cells over a one year period. Juvenile Chinook and coho salmon were also sampled for genetic analysis to define regional dispersal patterns. Key findings are： （1） Ecological function of the area＇s nearshore is complex, with very strong seasonal variation in fish use both within and across GMHT （geomorphic habitat type）; （2） GMHT link to nearshore function for fish use differs depending on the fish species and time of year. Surf smelt and sand lance were the most abundant. And they were seasonally used embayed, spit, and bluff shorelines more than lower rivers. Juvenile Chinook, coho, and chum salmon occurred in much lower density than forage fish species, and used lower rivers more than other GMHTs; （3） When GMHTs were combined and analyzed at the drift cell scale, the degraded drift cell had different ecological patterns than the intact drift cell; （4） Cross regional juvenile fish use of nearshore is an important component of habitat use： juvenile Chinook and coho from as far away as the Columbia River Oregon and Klamath River California utilize central Strait of Juan de Fuca shorelines. Forage fish species may do so as well. Drift cell and cross regional scales are therefore most important for accurately defining nearshore ecological function, management, and restoration actions.
