Coupling of hydrodynamic and spatial ecosystem models to assess spotted
seatrout population risks from exploitation and environmental changes
Jerald S. Ault, Jiangang Luo, and John D. Wang
University of Miami, Miami, FL
Traditionally, water quality, critical habitats, and fish stocks have each been
treated as separate management issues. However, pervasive resource declines and
widespread habitat destruction have emphasized the importance of taking a more
holistic view to resource management. Clearly, we need innovative predictive
tools to help evaluate mechanisms for effective spatial fishery management.
Explosive regional human population growth, overfishing and habitat degradation
in south Florida has stimulated system restoration projects that are redefining the
quality and functioning of the coastal ecosystem. Success of Everglades
restoration and other targeted fishery management strategies will be reflected in
changes in the size and abundance structure of fisheries and species composition
of the marine resource communities. Because spotted seatrout are sensitive
indicators of system environmental changes, we developed a spatial age
structured predator-prey model to assess seatrout population risks from
exploitation and environmental changes. The model couples the production
dynamics of a higher trophic level age-structured population (e.g., seatrout,
Cynoscion nebulosus) to a key prey (e.g., pink shrimp Farfantepeneaus duorarum)
through a dynamic array of biophysical processes. The model is based on
fundamental principles of bioenergetics, population ecology, and community
trophodynamics linked to a well calibrated Biscayne Bay hydrodynamic model
(Wang 1978, Wang et al. 1988, 2002). This is done by mathematically linking
bioenergetic principles of fish physiology, population ecology, fish-habitat
relationships, and community trophodynamics to a regional hydrodynamic
circulation and mass transport model. We focused on an important model
application on issue of expected ecosystem transitions from changes in freshwater
to “tide” under the comprehensive Everglades restoration plan. Specifically, we
evaluated impact to seatrout population productivity, fishery yields, and
ecosystem performance resulting from two alternative water management
scenarios associated with Everglades restoration, which are expected to affect the
timing, location and quantities of freshwater delivered to Biscayne Bay, Florida.
Jerald Ault, University of Miami, 4600 Rickenbacker Causeway, Miami,
FL33149
Phone: 305-361-4884, Fax: 305-361-4791, jault@rsmas.miami.edu