Modeling and analysis of fish populations and aquatic environments.
| Mission
Statement Current Projects Population Modeling
Bioenergetic
Models
Jeffrey
A Tyler, Ph.D.
Director & Chief Scientist 307 Old Mountain Rd Farmington, CT 06032 send email Dr. Tyler's C.V. (pdf) publication list (pdf) presentation list (pdf) 
updated 10 July 2007
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The work at Fisheries
Projections
addresses both applied and theoretical problems in fish population
modeling and environmental analysis. The aim of this work is
to
better understand the response of fish populations to changes in the
environment that result from causes both natural and human-induced.
Ultimately, the work should benefit the relationship between
humans and the fish populations that we both exploit and enjoy. The modeling tools used at Fisheries Projections include a range of individual-based models of fish populations, bioenergetic models of fish growth and graphical information system models of the environment. Environmental analysis centers on spatially-explicit analysis of environmental quality. Current Projects Population Modeling Population modeling at Fisheries Projections includes both applied and theoretical fish population questions. Muskegon River: Linking IBMs, GIS and HEC-RAS models Dr. Tyler (Fisheries Projections Chief Scientist) has developed an IBM of steelhead (Oncorhynchus mykiss) in a high-resolution, spatially-explicit description of the Muskegon River, Michigan. This work integrates output from HEC-RAS modeling of the Muskegon River hydraulics with GIS information of the river substrate and invertebrate population (HEC-RAS is a product of the US Army Corps of Engineers Hydrologic Engineering Center) .  The
modeling work
done by Dr. Tyler
plays a key role in the Muskegon
River Watershed Research Partnership's Mega Model Project.
The primary collaboators on this project include Dr.
Mike
Wiley, Dr.
Ed Rutherford and Dr. Catherine Riseng of the University of
Michigan's School of
Natural Resources and the Environment.The Steelhead-Muskegon River model (SHMKG) provides among the most comprehensive modeling efforts of a river and economically important fish popuation in the midwest if not in the entire U.S. At present, the combined modeling effort has completed one, 13 Km, segment of the river. Segment 18.2 has 510 cross sections and 43 cells/xs. Segment 18.2 represents approximately 10% of the Muskegon River downstream of Croton Dam. If future funding is approved the SHMKG model likely will be expanded to include all of the Muskegon River downstream of Croton dam as well as some of its tributaries. Results from the initial simulations of SHMKG were presented at the 2006 American Fisheries Society meeting in Lake Placid, NY. More recent results were presented at the 2007 International Association of Great Lakes Researchers at Penn State University (link to .pdf of presentation). Manistee River-Steelhead spatially-explicit IBM  The Manistee River-Steelhead IBM models an economically important fish population in a river section with low resolution spatial information on the phhysical habitat. The model is constructed for the Manistee River downstream of Tippy Dam. Data available for the Manistee River include only some instream flow results and measurements of water velocities conducted by Dr. Rutherford and his graduate students. High resolution HEC-RAS models are unavailable for this river. The Manistee River-Steelhead IBM demonstrates how a model can be constructed for envornments with little data on the physical habitat and thus may represent a viable approach for modeling fish populations in a generic tributary of Lake Michigan or other Great Lakes. Results of model simulations show that this population may be subject to significant density limitations in the fry life stage and that changes in both the flow and temperature regimes of the river may have detrimental effects on the population. These results have been presented at various American Fisheries Society meeting and the manuscript is currently under review at the Transactions of the American Fisheries Society. Environmental Analysis Environmental analysis at Fisheries Projections focuses on descriptions of the environment that relate directly to the value of the environment for the species of interest. The environmental analysis tools used here provide insight as to how changes in the environment may affect specific species of interest which is most useful when assessing the potential impact of environmental changes. Habitat Suitability/Weighted Usable Area Habitat Suitability Indices (HSI) or Weighted Usable Area (WUA) descriptions of the environment describe the fraction of the environment may be used by a fish species/life stage. HSI/WUA take into account only physical environment features and were originally developed for use with IFIM (instream flow incremental methodology) analyses of river flow.  Fisheries
Projections,
along with collaborators at the Universiry of Michigan, has developed a
dynamic-WUA model that assesses the suitability of the Muskegon River
on a daily basis reflecting daily changes in river hydraulics.The image here presents an average WUA for steelhead juveniles in river segment 18.2 during August 2000 (click here to view larger image). The spatial structure in the dynamic-WUA analysis is determined by the HEC-RAS output of water depth and velocity. Because the underlying data from the HEC-RAS simulations generates daily water outputs the dynaimc-WUA analysis can operate at a time scale as small as a day or as large as a year. Dynamic-WUA analysis such as this may be accomplished for any environment with suitable data and is not limited to rivers or to fish. Growth Rate Potential Growth Rate Potential (GRP) is the amount of growth that a fish of specific species and life stage may grow under a given set of conditions. This tool for environmental quality analysis was originally developed by Dr. Steve Brandt and colleagues in the 1990s. GRP depends on models of fish bioenergetics and foraging paired with data of water temperature and fish food availability. GRP provides a powerful relative measure of habitat quality that relates to a fish gowth which is key factor in the success or failure of fish populations. Fisheries Projections personnel have played important roles in the development of GRP analysis (GRP Map Maker, Technical Memo-110). GRP analysis of the Muskegon River for salmonids species is currently being developed in conjunction with the Muskegon River-Steelhead IBM. Most GRP analysis has been combined with acoustic data on forage fish populations and conducted in largely lentic environments such as the great lakes, western reservoirs or estuaries such as the Chesapeake Bay. The GRP analyisis of Muskegon River is the first such analysis combined with a hydraulics model such as HEC-RAS. Background Information Individual-Based Models Individual-Based Models (IBMs) simulate every individual in the population rather than the population as a whole as done in classical population models. As such, IBMs can demonstrate the presence of key population dynamics that must be assumed under classic population models. Density-dependent population growth is the most common population dynamics feature that may emerge from and IBM but must be assumed in a classic population model. In fisheries research IBMs have played an important role in understanding fish population dynamics. Much of the work originates in the EPRI funded CompMech project from the early to middle 1990s. This multi-million dollar research project examined the potential for compensatory mechanisms to operate in fish population dynamics. The modeling component of CompMech was headed by Drs. Don DeAngelis and Ken Rose while they were at the Oak Ridge National Laboratory. Spatially-Explicit IBMs Spatially-explicit IBMs describe the simulated environment for the population with a high degree of spatial resolution. Early IBMs for fish populations tended to describe the environment as a "homogenous, well-mixed box" and focus the modeling effort on differences between individuals in a population. Spatially-explicit IBMs provide a more realistic environment for fish popualtions and when linked to spatial data of real environments (e.g. Muskegon River-Steelhead IBM) may prove to be extremely powerful research and environmental remediation tools. Bioenergetic Models Bioenergetic models describe fish consumption or growth based on a simple mass-balance equation: consumption
= growth + costs
costs include: respiration, egestion, excretion and spacific dymamic action. The "Wisconsin Bioenergetic Models", developed at the University of Wisconsin and maintained by Wisconsin Sea Grant have been used extensively by fisheries researchers and managers. These models play a critical role in both fish IBMs and GRP analyses. |