An initial evaluation of management strategies for the southern bluefin tuna fishery

Abstract

1999. An initial evaluation of management strategies for the southern bluefin tuna fishery. -ICES Journal of Marine Science, 56: 811-826.Within the Commission for the Conservation of Southern Bluefin Tuna there has not been agreement on a mechanism for adjusting quotas for the resource. It has been proposed that development of a decision-rule-based management strategy is an issue of high priority, indeed a matter of urgency. Results are presented from an initial application of a Monte Carlo management strategy evaluation (MSE) approach aimed at developing a rebuilding strategy for the stock. Southern bluefin tuna (Thunnus maccoyii) provides a substantial test of the power of this approach to develop a decision framework that can cope with large uncertainties about the current state of the stock and conflicting information from the fishery that is used in stock assessment.The results indicate that a robust feedback decision-making framework can be developed which ensures fast rates of recovery across the broad range of interpretations about stock dynamics and current status of the resource. Among the harvest strategies examined, the F 0.2 , F 0.1 , and SSB/R strategies were clearly the most robust and consistent in terms of recovery and sustainability. Fast recovery rates were only achieved with strategies that had catches substantially below 1998 levels. Within the strategies examined, little scope exists for improvement in yield without a direct loss in recovery performance. For the MSE approach to succeed, the operating, sampling, and conditioning model components must incorporate the full uncertainty about the real stock and the sampling processes appropriately. There is clearly scope for improving and broadening the way uncertainties have been handled in this initial examination. In particular, uncertainties associated with the catch-at-age, the relationship between the c.p.u.e. and true abundance, and the conditioning of the historical population sizes in the face of inconsistent historical data, need further development. As the MSE approach requires conditioning to historical data, full and appropriate incorporation of uncertainty into stock assessment and conditioning would lead to a better basis for developing and evaluating management procedures that will work. 1999 International Council for the Exploration of the Sea

Bases conceptuales para la aplicacion de una evaluacion de estrategias de manejo (EEM) en sardina comun (Strangomera bentincki) y anchoveta (Engraulis ringens) en la zona centro sur de Chile

“…creación de modelos operativos que sean usados como base para determinar cómo un recurso en particular responde a futuros niveles de captura y esfuerzo. El modelo operativo es un modelo matemático usado para describir la dinámica de un recurso en pruebas de simulación, el cual puede ser de diversa complejidad estructural y comprender diferentes escalas de observación temporal y espacial, donde su condicionamiento estadístico es referido al proceso de ajuste a la información disponible (Polacheck et al, 1999). En este estudio se ha investigado los principales procesos poblacionales que gobiernan la dinámica de ambos recursos como son la alternancia, crecimiento estacional, dependencia ambiental y patrón de reclutamiento, para vincularlos con el desarrollo de modelos operativos y a la aplicación de EEM para sardina común y anchoveta.…”

Salvaged pearls: lessons learned from a floundering attempt to develop a management procedure for Southern Bluefin Tuna

“…Prior to this, an in depth illustration of the applicability of an MP approach to the SBT stock had been completed (e.g. Polacheck et al, 1999). The Commission agreed to develop an MP in 2000 (Anon., 2000).…”

Fisheries management in practice: review of 13 commercially important fish stocks

“…Conservation, management and optimal utilization are three objectives the Commission mentions in their Convention. (CCSBT 1994) The primary objective for the CCSBT is to have a spawning stock biomass at the level observed in 1980 by the year 2020 (Polacheck et al 1999;Polacheck 2002).…”

“…15 The biological nature of Southern bluefin tuna, it being a large, slow growing, fast swimming and highly migratory fish, makes it a difficult subject for which to study reproduction biology and population dynamics. The assessment is full of large uncertainties for both the biological parameters and input data (cited Polacheck et al 1999;Polacheck 2002).…”