Document Type

Thesis

Date of Degree Completion

Summer 2018

Degree Name

Master of Science (MS)

Department

Cultural and Environmental Resource Management

Committee Chair

Dr. Anthony Gabriel

Second Committee Member

Dr. Megan Walsh

Third Committee Member

Dr. Karl Lillquist

Abstract

This study looks at a portion of the designated critical habitat for the threatened southern distinct population segment of green sturgeon (Acipenser medirostris) in Willapa Bay, Washington. Willapa Bay is an intermediate size (258.7mi2) estuary on the southwest coast of Washington State, approximately 30 miles north from the mouth of the Columbia River. Recent studies completed by the National Marine Fisheries Service have shown that significant aggregations of green sturgeon in Willapa Bay occur during the late summer months, and foraging activity for burrowing ghost shrimp (Neotrypaea californiensis) is evidenced by small round feeding pits (30-60 cm diameter) in the intertidal substrate. The environmental factors of feeding sites were compared to non feeding sites nearby. The most prevalent foraging areas of the estuary were identified and associations between feeding sites and environmental factors may present themselves. Our findings show that green sturgeon are feeding in areas with fine-grained sediment (>2.0 phi). Feeding pit observations declined when surveying areas with thick eelgrass beds and increased in bare areas. No feeding pit activity was observed within aquaculture parcels adjacent to feeding sites. The majority of feeding pits were found between +0.25 m and +1.5 m MLLW, in terms of tidal elevation.

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