André E. Punt is a Professor in the School of Aquatic and Fishery Sciences at the University Washington,
Seattle, USA and currently the Director of the School. He is a keynote speaker at the My Fish symposium session on 'Incorporating knowledge on trade-offs and conflicting objectives into decision making'.
Fisheries management involves developing and implementing regulations on fishers to achieve societal management goals. Increasingly, some of the regulations, such as limits on catch or effort, are based on the outcomes of mathematical equations called management strategies that link the regulations to data collected from the fishery, such as catch-per-unit-effort and survey estimates of biomass. The selection of the management strategy for a fishery should take into account what is known about the system being managed, including the data that are available for fisheries management purposes, and the goals of the fishery management regime.
Computer simulation is used to compare alternative management strategies. This approach, referred to as management strategy evaluation or MSE, is used to evaluate the trade-offs among the management goals achieved by each management strategy being considered for possible adoption and use. MSE is used in many jurisdictions around the world to help fisheries decision-makers, and is increasingly being recommended for use in terrestrial systems.
Management strategy evaluation involves several steps, some of which are primarily technical, and others that involve researchers conducting the MSE working with the decision-makers to ensure that the results are relevant to the needs of the decision-makers. The technical steps involve developing a set of models of the system to be managed. These models capture the key uncertainties that may frustrate the ability of management strategies to achieve the management goals. This modelled system is then projected forward a number of times, each time with a different management strategy applied. The models of the system may include factors related to the stocks being managed, the ecosystem in which it is located, the impact of fishing on the fished stocks as well as on habitat and threatened and vulnerable species, and future monitoring strategies.
MSE evaluations seldom identify management strategies that will satisfy all of the goals of the decision makers simultaneously, i.e. each strategy will achieve a different trade-off amongst the goals. It is therefore necessary to correctly identify management goals and represent them mathematically using performance statistics, and to display the trade-offs among the management goals to the various audiences who provide input into decision making.
The ideal approach to obtaining management goals and performance statistics is through workshops with decision-makers, but this has only been possible in a few cases, all of which have been in Australia. In most cases, the decision-makers provide qualitative goals that are represented mathematically by the researchers. Most MSEs have focused on single-species goals, but there are now more examples where the goals relate to multiple species and entire ecosystems.
Researchers can assist the decision-makers as they select among the management strategies by summarizing the results of the complex models in ways that highlight the trade-offs and identify those management strategies that will not satisfy the goals. These tools include plots that illustrate how catches and population status are related for each management strategy, as well as plots that display multiple dimensions of performance simultaneously.
Two basic approaches for selecting among the management strategies can be applied. One of these involves establishing minimum performance standards, particularly in terms of resource conservation, and only considering management strategies that achieve those standards. The other approach involves simply finding the 'best' strategy, although most decision makers will implicitly impose some performance standards.
The selection of a management strategy for a fishery is a collaborative exercise between decision makers, researchers, and stakeholder groups. Each participant in the process has a distinct role, and communication among the groups is essential to successfully finding the management strategy that will achieve the management goals. The approaches I have outlined here should help with the communication process and help to better achieve the ultimate goal of fisheries to provide maximum benefits to fishers and fishing communities, but also to ensure healthy ecosystems.
André E. Punt, School of Aquatic and Fishery Sciences at the University Washington, Seattle, USA.