Fisheries management through optimal sustainable policies with constant effort in random environments

Abstract

Event Abstract Back to Event Fisheries management through optimal sustainable policies with constant effort in random environments Nuno M. Brites1* and Carlos A. Braumann1, 2 1 Centro de Investigação em Matemática e Aplicalções, Instituto de Investigação e Formação Avançada, Universidade de Évora, Portugal 2 Departamento de Matemática, Universidade de Évora, Portugal To describe the growth of a harvested population when the environment is subjected to random fluctuations one can use Stochastic Differential Equation models. We consider logistic and Gompertz models for the average natural growth to which we subtract a harvesting yield term based on a constant or variable fishing effort. There is previous work on the optimal design of the harvesting policy with the purpose of maximizing the expected accumulated profit (discounted by a depreciation rate) over a finite time horizon. We consider a quite general profit structure which includes linear prices per unit yield and linear costs per unit effort. The harvesting efforts of the optimal policies vary with the randomly varying population size and such policies can, under certain conditions, even be of bang-bang type. These policies are not applicable to harvesting since they need to constantly evaluate population size and require very frequent randomly determined changes in harvesting effort. Our approach, based on sustainable and applicable fishing policies, leads to sustainability of the population and to a stationary distribution of the population size and do not require evaluation of population size. We determine the constant harvesting effort policy that optimizes the expected sustainable profit per unit time and check what we lose profitwise by using this policy instead of the optimal inapplicable policy with variable effort. Using Monte Carlo simulations, we show that, for common situations, our approach is almost as profitable as the first. Acknowledgements Nuno M. Brites and Carlos A. Braumann belong to the Centro de Investigação em Matemática e Aplicações, Universidade de Évora, a research centre supported by FCT (Fundação para a Ciência e a Tecnologia, Portugal). The first author holds a PhD grant from FCT (ref. SFRH/BD/85096/2012). Keywords: Fishing effort, optimal sustainable policy, logistic model, Gompertz model, stochastic differential equations Conference: IMMR | International Meeting on Marine Research 2016, Peniche, Portugal, 14 Jul - 15 Jul, 2016. Presentation Type: Oral presentation Topic: Fisheries and Management Citation: Brites NM and Braumann CA (2016). Fisheries management through optimal sustainable policies with constant effort in random environments. Front. Mar. Sci. Conference Abstract: IMMR | International Meeting on Marine Research 2016. doi: 10.3389/conf.FMARS.2016.04.00113 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 14 Apr 2016; Published Online: 13 Jul 2016. * Correspondence: Dr. Nuno M Brites, Centro de Investigação em Matemática e Aplicalções, Instituto de Investigação e Formação Avançada, Universidade de Évora, Évora, Évora, 7000-671, Portugal, brites@uevora.pt Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Nuno M Brites Carlos A Braumann Google Nuno M Brites Carlos A Braumann Google Scholar Nuno M Brites Carlos A Braumann PubMed Nuno M Brites Carlos A Braumann Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.