Preliminary assessments of landscape sources of stress to fish habitats in Alaska and Hawaii

One of the near-term objectives of the National Fish Habitat Action Plan is to conduct an assessment of the condition of U.S. fish habitats to facilitate allocation of resources for habitat conservation.  Hawaii and Alaska had unique biological circumstances and data limitations and thus required slightly different assessment approaches from the lower 48.  In Alaska, where geospatial, local habitat, and fish community data in rivers were sparse, we relied only on variables about landscape sources of stress to rivers.  Specifically, we used principal components analysis to identify the linear combination of stress source variables that best explained variation in our anthropogenic dataset.  We used this as a composite disturbance gradient to assign relative landscape disturbance scores to 8-digit USGS hydrologic units.  In Hawaii where native fish species diversity is low and rivers habitats are unique, we used an approach similar to the lower 48 States wherein we used structural equation modeling to assess the influences of nested landscape sources of stress on each other and on locally calibrated measures of habitat quality and biotic integrity.  Each case illustrates general patterns in landscape disturbance, but points to needs for standardization of data sources between these states and the lower 48.