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Assessing the Relative Importance of Estuarine Nursery Habitats – a Dungeness Crab (Cancer magister) Case Study
Citation:
Lewis, N., D. Young, C. Folger, AND Ted DeWitt. Assessing the Relative Importance of Estuarine Nursery Habitats – a Dungeness Crab (Cancer magister) Case Study. Estuaries and Coasts. Estuarine Research Federation, Port Republic, MD, , s12237-020-00821-1, (2020). https://doi.org/10.1007/s12237-020-00821-1
Impact/Purpose:
Scientists from WED’s Pacific Coastal Ecology Branch in Newport, OR assessed the relative importance of estuarine habitats for production of Dungeness crabs (Cancer magister). Production of these crabs is an important final ecosystem service to U.S. Pacific coastal communities in that harvest of Dungeness crabs is currently the most valuable fishery to Oregon and Washington. For this study, surveys of juvenile Dungeness crabs and adjacent intertidal habitats were conducted in three Oregon estuaries (Tillamook, Yaquina, and Alsea). These data were subsequently analyzed to determine relationships between juvenile Dungeness crab abundance and the mosaic of estuarine habitats (e.g., channels, seagrass beds, tide flats) within and across estuaries. Results showed that side channels (lateral to the main channels) in ocean-dominated reaches of estuaries supported the highest abundance of juvenile crabs; further analyses suggested that variation in crab abundance was actually driven by higher salinity in the lower estuary and the density of a burrowing shrimp (Upogebia pugettensis) on unvegetated tideflats adjacent to the side channels. Results from this study offer resource managers insight into the differential importance of estuarine habitat types for 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:
Estuaries serve as important nurseries for many recreationally and commercially important fisheries species. The value of these estuaries to fisheries species has long been assessed at an estuary-scale or between generalized habitat types. More recently, conceptual approaches (i.e., seascape) have advocated for complex habitat-scale assessments that integrate multiple response metrics and ecological processes across heterogeneous habitats. Although this approach is ecologically representative, implementing such an extensive framework may not be feasible for resource-limited organizations. In such cases, we posit that resource managers can improve their understanding of the relative values that estuarine habitats provide to fisheries by integrating attainable aspects of the seascape approach into a more traditional single response model. Using Dungeness crab (Cancer magister) as a case study, we applied a spatially explicit hybrid approach to assess the relative values of estuarine habitat to an important fishery species within three Oregon estuaries (Tillamook, Yaquina, and Alsea bays). We analyzed the abundance of juvenile C. magister and the mosaic of estuarine habitat (data from intertidal habitat surveys and the National Wetlands Inventory) within defined home-ranges, which allowed for movement of crabs among heterogeneous habitats. Results showed that side channels of intertidal flats in ocean-dominated reaches of estuaries supported the highest abundance of juvenile crabs; further analyses suggested that variation in crab abundance was driven by higher salinity in the lower estuary and the density of a burrowing shrimp (Upogebia pugettensis) on adjacent unvegetated tide flats. This hybrid method produced a habitat-specific model that better predicted juvenile C. magister abundance than a model based on generalized habitat categories.
URLs/Downloads:
DOI: Assessing the Relative Importance of Estuarine Nursery Habitats – a Dungeness Crab (Cancer magister) Case Study