übertool: web applications for ecological risk assessment (beta version)
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Cloud-based environmental models used by the USEPA for evaluating pesticide risks to ecosystems under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and the Endangered Species Act (ESA).
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Fox Surplus Yield Model Overview

 

Based on Gompertz growth function, William W. Fox established an alternative surplus-yield model which created an exponential relationship between fishing effort and population size:

 

 

Fox surplus yield model:

  • considers population as one unit of biomass, without age structure
  • assumes people can harvest the surplus production without endangering the population