Identifying Risks of Geoduck Aquaculture: The Role of Larval Transport
Juan Valero, School of Aquatic and Fishery Sciences, University of Washington
Abstract
A primary concern regarding possible impacts of geoduck aquaculture is the potential adverse effects on wild geoduck populations. Potential negative effects include genetic interactions between wild and farmed geoducks, spread of diseases, and conflicts between different users of the potentially affected resource. While adult geoducks remain buried in the substrate during their lifetime, their larvae spend between 2 and 8 weeks in the water column. This larval-dispersal stage is a crucial link between local and regional wild geoduck populations. Transport of larvae spawned by farmed geoducks is the primary mechanism for genetic interaction between cultured and wild geoducks and could also play a role in transmission of potential diseases. Therefore, understanding larval transport on both local and regional scales is critical for evaluating the location of cultured areas, monitoring impacts, and resolving user conflicts over potential impacts on natural geoduck productivity. Understanding larval transport and its variability is also necessary for determining the appropriate temporal and spatial scales for risk assessments and for scaling up local effects to the regional dynamics of the whole system. During their time in the water column, larvae are affected by a complex set of biological and physical factors that ultimately determine their dispersal and settlement to the bottom at the end of the larval phase. Currently, knowledge of such effects and their interaction with the complex circulation of Puget Sound is very limited for geoduck larvae. In this talk, I discuss the current state of the knowledge as well as major gaps in understanding the ecology and population dynamics of geoducks, with implications to the study of geoduck larval transport and aquaculture. I also discuss current approaches and modeling efforts used to study larval transport and their applicability to understanding geoduck larval transport, with particular reference to current geoduck aquaculture issues.