  Mathematical and statistical models underlie many of the world's most
important fisheries management decisions. Since the 19th century, difficulty
calibrating and fitting such models has been used to justify the selection of
simple, stationary, single-species models to aid tactical fisheries management
decisions. Whereas these justifications are reasonable, it is imperative that
we quantify the value of different levels of model complexity for supporting
fisheries management, especially given a changing climate, where old
methodologies may no longer perform as well as in the past. Here we argue that
cost-benefit analysis is an ideal lens to assess the value of model complexity
in fisheries management. While some studies have reported the benefits of model
complexity in fisheries, modeling costs are rarely considered. In the absence
of cost data in the literature, we report, as a starting point, relative costs
of single-species stock assessment and marine ecosystem models from two
Australian organizations. We found that costs varied by two orders of
magnitude, and that ecosystem model costs increased with model complexity.
Using these costs, we walk through a hypothetical example of cost-benefit
analysis. The demonstration is intended to catalyze the reporting of modeling
costs and benefits.
