Patterns in Use of Estuarine Habitat by Juvenile English Sole (Pleuronectes vetulus) in Four Eastern North Pacific Estuaries

English sole (Pleuronectes vetulus) is one of a few commercially important marine fishes on the Pacific coast of North America that use estuarine areas as nurseries for juvenile stages. Trawl surveys of four United States Pacific Northwest estuaries were conducted to determine spatial patterns of juvenile English sole residence in estuaries during 1998-2000. Additional data from 1983-1988 were also analyzed. Two size classes of juvenile English sole were identified during surveys, with densities of small (Total length [TL] < 50 mm) sole ranging from 0 to 11,300 fish ha-1 across all sites, and densities of large (TL 50-150 mm) sole ranging from 0 to 33,000 fish ha-1 across all sites. Principal components analysis of static habitat data collected at each trawl survey site was used to define habitat types within each estuary, and discriminant function analysis was used to test the resulting classification scheme. Both small and large cohort English sole used lower side channel locations at significantly higher densities than other estuarine areas. Small English sole also showed significant relationships with both bottom temperature and depth. These patterns in habitat use were consistent across all estuaries and indicate that English sole used shallow depth areas surrounded by extensive tidal flats, where temperatures were optimal for growth. The analysis also suggested a carrying capacity may exist for large English sole in nursery estuaries.