GIS-BASED MODELING: NUTRIENTS, PHYTOPLANKTON AND AQUACULTURE
Jack Rensel1, Dale Kiefer2,3 and Frank O’Brien3
1Rensel Associates Aquatic Sciences, Arlington WA
2University of Southern California, Los Angeles, CA
3System Science Applications, Lost Angeles, CA
Fish, shellfish and seaweed aquaculture are the fastest growing forms of food production in the
world. Approximately one half the fish consumed by humans is produced by fish farms. U.S.
production in marine farms is far less than 1% of the total, contributing to the > $10 billion
seafood import imbalance annually. All forms of aquaculture may have potential adverse
effects on the marine ecosystem unless sound principals of siting and operation are practiced
by industry. These principals include optimization of siting that benefits both the cultured fish
and the environment, operational BMPs such as feed waste monitoring, and performance
standards to insure industry compliance.
In Washington State, such principals also involve reducing nutrient loading and requiring f fish
aquaculture siting in “non-nutrient-sensitive” waters that are hydrodynamically active and
characterized as being light-limited for phytoplankton production. In such areas, adding
ammonium and urea from the cultured fish is ecologically inconsequential. Siting is not allowed
in shallow, poorly-flushed, vertically-stratified and nutrient-sensitive backwaters that are
already typically impacted by nutrient runoff from various land use practices. Intensive
monitoring, open ocean or offshore aquaculture, integrated multitrophic aquaculture (fish,
filter feeders, detritivores and seaweed combinations), ecosystem-based management, use of
carrying capacity models and coupled biological-physical model are additional strategies for
increasing the sustainable supply of seafood without inducing significant adverse effects.
With support from NOAA and USDA, we have developed a water column and benthic effects
simulation software modeling program (AquaModel) to help locate individual farm sites and
manage coastal zones. The software operates in a unique 4D (Length, Width, Depth, Time)
Geographic Information System in Windows operating systems and is user friendly. It has been
applied in several locations throughout the world from Hawaii to Puerto Rico and has been
validated through use of extensive NPDES monitoring data from the Pacific Northwest collected
over the past 22 years.
The presentation includes a brief overview of model components and illustration of near-field
results from a proposed offshore demonstration farm in 100 m depth and 5 miles offshore of
San Diego to be operated by Hubbs-SeaWorld Research Institute. Model application in a farfield mode in the State of Hawai’i with the state Department of Agriculture, University of
Hawai’i and industry partners will be discussed too.