Intertidal Aquaculture as Habitat in Pacific Northwest Coastal Estuaries: Considering Scale
Brett Dumbauld, USDA Agricultural Research Service
Current management policies for estuarine tidelands in the Pacific Northwest are based on general descriptors and perceptions, often based on research conducted elsewhere. This has resulted in regulations such as a “no-net loss of aquatic vegetation” policy which tend to be applied on very small spatial (individual permit) scales and very short temporal (what is the habitat present today?) scales. A review of recent studies conducted at these restricted scales does in-part confirm the general value of seagrass as structured habitat, however Pacific Northwest estuaries appear to function slightly differently and the role of cultured shellfish as habitat in these systems has only recently been described. Scale is clearly an issue and recent mapping efforts in Willapa Bay, Washington suggest that managers should view shellfish aquaculture from an estuarine landscape perspective and at broader temporal scales. Techniques that have recently been applied for analyzing the role of terrestrial agriculture in otherwise forested or grassland ecosystems suggest that habitat configuration such as movement corridors and edge-interior ratios could be important. Preliminary results suggest that traditional policies which seek to conserve other invertebrate or vertebrate fishery species which use these estuaries as nurseries by protecting one habitat (aquatic vegetation), should be reconsidered once studies are conducted at this landscape scale. Considering local differences, best management practices could then also be regulated and implemented at these scales.