EEO Tuna

Context

In recent years, ICCAT and IOTC have strengthened the implementation of management measures aimed at conserving tuna stocks, based on scientific advice derived from stock assessment processes. These processes rely on numerical modelling tools and simulations to estimate the exploitation status of the resources.

At the same time, both organisations are advancing towards the adoption of automated management measures, such as harvest control rules, within the framework of Management Strategy Evaluation (MSE), with the aim of achieving more predictable, stable and precautionary management systems.

AZTI actively contributes to these processes, particularly in North Atlantic albacore and tropical tuna stocks in the Atlantic and Indian Oceans. The increasing methodological complexity and scientific requirements within both organisations make it necessary to strengthen AZTI’s contribution through studies that enhance and update stock assessment and MSE processes.

Objectives

The overall objective of the project is to contribute to improving stock assessment processes and Management Strategy Evaluation (MSE) for North Atlantic albacore and tropical tuna species (yellowfin, bigeye and skipjack) in the Atlantic and Indian Oceans.

More specifically, the project aims to:

• Lead the second development phase of the MSE for North Atlantic albacore, by conditioning operating models that incorporate biological changes attributable to climate change, implementing observation error functions that reflect uncertainty across available time series, and evaluating the effectiveness of alternative harvest control rules, including empirical rules and those based on biomass production models.
• Lead the development of multispecies MSE for tropical tuna, integrating the results of the most recent assessments of the three stocks in each ocean and building a multispecies management framework that accounts for the technical interactions between fishing gears that simultaneously target these species. This framework will enable the evaluation of control rules that ensure the joint sustainability of the three stocks in both oceans.

Expected impact

The implementation of the MSE process for North Atlantic albacore has made a decisive contribution to the gradual stabilisation of the management of this stock, which is of major importance for the Basque coastal tuna fleet. Since the process began in 2011, its evolution has led to the adoption of a management strategy in 2021. The update of this mechanism will help consolidate a predictable and precautionary management approach in the coming years, adapted to new scientific and environmental conditions.

For tropical tuna in the Indian and Atlantic Oceans, current management measures have primarily focused on conserving the most overexploited stock in each region. The development of a multispecies MSE will enable progress towards a management system that considers the exploitation status of the three stocks in each ocean in an integrated manner, facilitating the adoption of stable and automated measures aligned with current discussions and needs within ICCAT and IOTC, and oriented towards the overall sustainability of the fisheries.

Funding