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Understanding the potential for estuarine habitat types to predict juvenile Dungeness crab densities
Citation:
Lewis, N. AND T. DeWitt. Understanding the potential for estuarine habitat types to predict juvenile Dungeness crab densities. CERF, Mobile, AL, November 03 - 07, 2019.
Impact/Purpose:
Scientists from EPA’s Pacific Coastal Ecology Branch in Newport, OR conducted surveys of juvenile Dungeness crab (Cancer magister) and adjacent intertidal habitats in four Oregon estuaries (Tillamook, Yaquina, Alsea, and Coos). These data were subsequently analyzed to determine the relationships between juvenile Dungeness crab and specific habitat types (e.g., seagrass and burrowing shrimp habitats) within and across estuaries. Preliminary analyses show that burrowing shrimp habitat is perhaps the most significant predictor of juvenile crab density. Other habitat types also contribute to the explanation of crab densities; however, these vary by estuary, which may indicate inter-estuary variability. Results from this study offer resource managers insight into the differential importance of estuarine habitat types on Dungeness crab, which are highly sought in recreational and commercial fisheries. In addition, the spatial patterns of these habitat types can allow managers and stakeholders to make more informed decisions about habitat restoration, conservation, and management to increase the abundance of this valuable species.
Description:
Shellfish production is a well-known and important ecosystem service of estuaries throughout the world, but the contribution of wetland habitat types to that production has not been characterized for U.S. Pacific Northwest estuaries. In Oregon, Dungeness crabs (Cancer magister) provide recreational and commercial harvest opportunities that make it the most economically valuable fisheries species in the state. Crab larvae settle and grow in estuaries and on the continental shelf, but those reared in estuaries grow faster and are larger at reproductive maturity. Extensive summertime trawl surveys and intertidal habitat surveys were conducted within four Oregon estuaries (Tillamook, Yaquina, Alsea, and Coos) to test the hypothesis that juvenile Dungeness densities are more positively correlated with seagrass (Zostera marina) habitat than other habitat types (e.g., burrowing shrimp and bare mudflat habitats), both within and across estuaries. Preliminary analyses indicate that the positive influence of burrowing shrimp habitat on juvenile crab density may be greater than that of seagrass habitat, contradictory to our initial hypothesis. We also examine the geospatial relationships between juvenile Dungeness crabs and the distribution of National Wetlands Inventory (NWI) habitat classes, channel size, salinity, and water temperature. Results from this study provide resource managers with valuable information for prioritization of habitat types for restoration, conservation, or enhancement for the purpose of increasing the abundance of Dungeness populations valued by local fisheries.