PT - JOURNAL ARTICLE AU - Nao Takashina TI - On the spillover effect and optimal size of marine reserves AID - 10.1101/853879 DP - 2019 Jan 01 TA - bioRxiv PG - 853879 4099 - http://biorxiv.org/content/early/2019/11/25/853879.short 4100 - http://biorxiv.org/content/early/2019/11/25/853879.full AB - Marine reserves are an essential component of model fisheries management. As implementing marine reserves induces an inherent tradeoff between the harvesting and conservation, to solidify the insight into fisheries management with marine reserves is fundamental for management success. Finding an optimal reserve size that improves the fishing yield is not only theoretical interest but also practically important to assess the underlying tradeoffs and to facilitate decision making. Also, since the species migration determines the degree of the spillover effect from a marine reserve, it is a key consideration to explore the performance of marine reserve. Here, we investigate an optimal reserve fraction and its management outcome under various spillover strength via a simple two-patch mathematical model, in which one patch is open to fishing, and the other is protected from fishing activities. The two-patch model is approximated by a single population dynamics when the migration rate is sufficiently larger than the growth rate of a target species. In this limit, it is shown that an optimal reserve size exists when the pre-reserve fishing is operated at the fishing mortality larger than the fMSY, the fishing mortality at the maximum sustainable yield (MSY). Also, the fishing yield with the optimal reserve size becomes as large as MSY in the limit. Numerical simulations across various migration rates between two patches suggest that the maximum harvest under the management with a marine reserve is achieved in this limit, and this contrasts with the conservation benefit in which is maximized at the intermediate migration rate.