HOOD CANAL (WA)

To better manage estuarine resources, it is important to develop a detailed understanding of the ecological processes and interactions that control and regulate populations of organisms, such as anadromous salmon (Oncorhynchus spp.) of the Pacific Northwest (PNW), that depend at some point in their life history upon the integrity of estuarine habitats. In Hood Canal and the Strait of Juan de Fuca, there is considerable evidence (Ames et al., 2000) that juvenile summer chum salmon (O. keta) rely on “natural beaches, eelgrass beds and unimpacted drift cells to provide productive, protected migratory corridors” as they transition from river delta rearing areas to open-water (Simenstad, 2000). Eelgrass beds form a nearly “continuous band” around the lower intertidal and sub tidal regions of Hood Canal from depths of about +1.8 m to –6.6 m (Phillips, 1984). Many factors can affect the quantity and structure of Hood Canal’s eelgrass beds and beaches including: filling, excavation, jetty construction, shoreline development (e.g., bulkhead and dock construction), vegetation destruction (Simenstad, 2000), and eutrophication. In turn, these factors can also affect the fitness of migrating salmon at multiple, interacting spatial and temporal scales (Cracknell, 1999; Simenstad and Cordell, 2000; Simenstad et al., 2000) making it difficult to predict the consequences of these perturbations.

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Composite of multiple flightlines in the Skokomish Marsh

The ability to resolve estuarine habitat features depends on the spatial and spectral resolution of the imagery.

IR-like image generated from 3 of the 21 hyperspectral bands 100 pixel (450 m) test blocks for vegetation assessment Notice thin strip of eelgrass/algae at waterline

EcoTrust's Beaver

Sampling Estuarine Plant Communities

We collected 19-band CASI imagery along the shoreline of Hood Canal during (+/- 3 hr) a spring low tide series from 29 June to 5 July 2000. We collected 145 overlapping flightlines ranging in length from approximately 0.9 to 20.0 km along most (~70%) of the shoreline Each pixel represented an area of 2.25 m^2 on the ground. Initial processing of 19 flightlines in four non-contiguous focal areas covered approximately 84.3 km of Hood Canal shoreline.

We geocorrected the CASI imagery to +/- 4.8m to 23.5 m RMSE using GCP targets and DOQ features visible in the imagery.

We found good agreement between classified eelgrass polygons and existing eelgrass beds. For the most of the other habitat classes, there was also good agreement except for the oyster bed cover class (Focal Areas 1-3) and the Brown Algae class (FocalArea 4). Our inability to correctly separate oyster beds from wet sand/gravel/cobble and brown algae was most likely due to the relatively low number of training sites. In addition, ‘’sand’ and ‘mixed sand/gravel’ classes, separated in Focal Area 4, were combined in Focal Areas 1-3 primarily due to differing degrees of wetness. We did not pursue improving the classification of non-eelgrass habitat types since they were not the primary objective of this study.

Reports and Publications

Final Report :

Habitat Technical Report: Assessment of Intertidal Eelgrass Habitat Landscapes for Threatened Salmon in the Hood Canal and Eastern Strait of Juan de Fuca, Washington State

Charles 'Si' Simenstad

Wetland Ecosystem Team
School of Fisheries
University of Washington

Assessment of Estuarine and Nearshore Habitats for Threatened Salmon Stocks in the Hood Canal and Eastern Strat of Juan de Fuca, Washington State: Focal Area. Technical Report, Point No Point Treaty Council. 26 pages + Figures.

Garono, R. J., R. Robinson, C. Simenstad, and H. Ripley. In review. Using high spatial resolution hyperspectral imagery to map intertidal habitat structure in Hood Canal (WA). Proceedings of the Alliance of Marine Remote Sensing, Wolfville, Nova Scotia.

Simenstad, C. A., R. J. Garono, R. R. Robinson, and P. A. Frost. In press. Landscape analysis of eelgrass (Zostera marina) habitat structure using remote sensing: application to assessing impacts of shoreline modifications. Second Joint Meeting of the Coastal Environment Science and Technology (CEST) Panel of the United States-Japan Cooperative Program in Natural Resources (UNJR), 25-29 October 1999, Silver Spring, MD and Charleston, NC, USA.

Garono, R. J., C. A. Simenstad, and R. Robinson. 2000. Using High Spatial Resolution Hyperspectral Imagery to Describe Eelgrass (Zostera marina) Landscape Structure in Hood Canal, WA. Proceedings of the 17th International Conference of The Coastal Society, Portland, OR USA. 582-591.