Bioeconomic Drivers of Exploitation Dynamics in Trophic Systems

The “fishing down the food chain” effect is one of the most widely cited hypotheses in all of fisheries science.  A question it raises however, is: why would we expect independently operating fishermen in all kinds of ecosystems to consciously choose to fish down the food chain?  What mechanisms might be driving the alleged fishing down pattern?  These are questions about motivating forces behind human behavior.  Economics is the study human behavior and economists have well-tested frameworks that explain behavior in all kinds of settings, including rates of exploitation of fisheries.  Many of these economic theories have analogues in behavioral ecology and hence should be familiar to ecologists.  In this paper we modify a widely used Lotka-Volterra bioeconomic model of exploitation behavior to study the fishing down hypothesis.  We characterize a stylized trophic system in terms of primitives, namely parameters summarizing biological and economic drivers and interconnections between biological and economic components.  We explore plausible parameter sets and simulate consequent patterns of exploitation, including alternatives to the fishing down hypothesis.