PARTICLE DEPOSITION ANALYSIS TO INFORM ENVIRONMENTAL MODELING FOR RED DRUM AQUACULTURE IN THE GULF OF MEXICO

Troy Rezek*, J. Barry King, and James A. Morris, Jr.
JHT Inc., Affiliate of NOAA
NOAA National Ocean Service
National Centers for Coastal Ocean Science
Marine Spatial Ecology Division
101 Pivers Island Road
Beaufort, North Carolina 28516  
troy.rezek@noaa.gov
 

Environmental modeling of ocean net-pen aquaculture is driven by predicting how solid materials fall through the water column to the seafloor.  Model parameters of sequential ocean flow vectors and the mapping of the benthos all contribute to calculating where the falling solids stop moving and interact with seafloor.  One crucial model input parameter is the velocity at which fecal materials fall through the water column by gravity.  Salmon fecal settling velocities, density, and shape factor drag coefficient have been investigated on multiple occasions and are the default values in major net pen models since salmon producers are the primary model consumers.  It is anticipated that net pen aquaculture will expand into the Gulf of Mexico cultivating warmer water species than salmon such as red drum.  We are investigating red drum fecal settling velocities and mass fractions using various feed types and fish sizes to better understand if and how settlement behaviors are different from salmon.  To do so, we have constructed a variable speed flume apparatus capable of measuring settling velocities.  Here, we present the first data from the fecal settling velocity trials and provide preliminary comparisons to salmon values.