52 SEPTEMBER 2013 • WORLD AQUACULTURE • WWW.WAS.ORG Geographic Information Systems (GIS) have been widely used for the display, management and communication of georeferenced information in terrestrial and aquatic ecosystems. In shellfish aquaculture, GIS has been applied to site selection studies of bivalve mollusks (Congleton et al. 1999, Arnold et al. 2000, Longdill et al. 2008). More recently, ecosystem modeling has been used to predict the carrying capacity of estuaries (Ferriera et al. 2008, Nunes et al. 2011) but this approach does not have sufficient spatial resolution to be useful on an individual farm scale. Furthermore, because it does not account for boundary layer physics or aquaculture structure porosity, carrying capacity models lack realistic representation of food supply as affected by current flow in and around suspended or bottom culture systems. Finally, inadequate representation of the drivers of shellfish growth, especially the detrital component of suspended particulate matter, has limited the accuracy and utility of such models (Hawkins et al. 2013). A practical tool that is useful to shellfish farmers is needed to select good sites and manage them for optimal growth rates and seed-to-harvest yields. Funded by the USDA Northeast Regional Aquaculture Center (NRAC) and the Maine Aquaculture Innovation Center (MAIC), an international team of shellfish farmers, shellfish biologists, hydraulic engineers and software developers created ShellGIS: a Dynamic Tool for Shellfish Farm Site Selection Carter R. Newell, Anthony J. S. Hawkins, Kevin Morris, John Richardson, Chris Davis and Tessa Getchis a shellfish GIS software (called ShellGIS) that is designed to analyze shellfish farming practices in space and time, account for the interactive effects of seeding density, culture type and hydrodynamics. ShellGIS uses hydrodynamic flow models (MIKE 21, Warren et al. 1992, Fig. 1) and a shellfish growth model1 that has been calibrated for 13 of the most-commonly cultured shellfish species to predict the growth rate of shellfish at different sites using different culture strategies (i.e. suspended or bottom culture). Data Requirements ShellGIS is designed to be an affordable and widely used tool for shellfish aquaculture site selection and farm management. In addition to identification and selection of a particular species, the following types of data are required to prepare ShellGIS for a particular area: • Hydrodynamic model: bathymetry and tidal elevations. • Environmental data: temperature, salinity, food availability (total particulate matter, particulate organic matter, chlorophyll a) and dissolved oxygen (if relevant) every 2 weeks through a growing season. • Culture practice information: bottom, suspended or trestle design; cost of seed, market value. FIGURE 1. Output of 50-m grid flow model vectors on the ebb tide for the upper Damariscotta River, Maine. FIGURE 2. Flow-through apparatus used to measure in-situ biodeposition in Eastern oysters. Funded by the USDA Northeast Regional Aquaculture Center (NRAC) and the Maine Aquaculture Innovation Center (MAIC), an international team of shellfish farmers, shellfish biologists, hydraulic engineers and software developers created a shellfish GIS software (called ShellGIS) that is designed to analyze shellfish farming practices in space and time, account for the interactive effects of seeding density, culture type and hydrodynamics.
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