Nature Reserves as a Bioeconomic Management Tool: A Simplified Modelling Approach

This paper demonstrates analytically how a nature reserve may protect the total population, realize maximum sustainable yield (MSY) and economic yield (EY) and how this depends on biological growth, migration, reserve size and economic parameters. The pre-reserve population is assumed to follow the logistic growth law and two post-reserve growth models are discussed to explore the importance of model assumptions for assessment of reserves. The post-reserve growth has either a common carrying capacity as in the pre-reserve case, or each sub-population has its own carrying capacity proportionate to its distribution area. A combined model, as a continuum of the two models, is also formulated and briefly discussed. Population protection against extinction is assured against low cost harvesting, including zero cost, when relative reserve size is greater than relative migration. Reserve size may be tuned to realize MSY in one model, but not in the other. Economic yield is generally greater in the former, but maximum EY cannot be realized in any one.