Climate-Driven Variation in Yellowfin Tuna Productivity in the Western and Central Pacific Ocean Inferred from a...

Area of Science:

• Fisheries Science
• Climate Change Ecology
• Population Dynamics

Background:

• Effective management of pelagic fish stocks necessitates understanding temporal variations in population productivity, especially under climate change.
• Yellowfin tuna (Thunnus albacares) are a key species in the western and central Pacific Ocean, requiring robust assessment methods.

Purpose of the Study:

• To evaluate the productivity dynamics of yellowfin tuna in the western and central Pacific Ocean using a time-varying parameter model.
• To examine the influence of environmental variability on yellowfin tuna productivity.
• To explore uncertainties in productivity estimates and biological reference points.

Main Methods:

• Application of a stochastic surplus production model in continuous time (SPiCT) with time-varying parameters.
• Exploration of multiple time-varying parameterization scenarios to assess uncertainty.
• Utilized generalized additive models to link environmental variables with time-varying productivity.

Main Results:

• Productivity estimates showed consistent temporal patterns across different modeling scenarios, though magnitude and uncertainty varied with model structure.
• The Pacific Decadal Oscillation (PDO) and mixed layer thickness (MLT) demonstrated significant positive associations with maximum net productivity.
• Higher PDO values and greater MLT were correlated with increased population productivity.

Conclusions:

• Environmental variability, particularly PDO and MLT, plays a crucial role in shaping the time-varying productivity of yellowfin tuna.
• Incorporating environmental indicators into state-space models is feasible and provides a valuable framework for interpreting stock dynamics.
• This approach supports the development of ecosystem-based fisheries management strategies for yellowfin tuna in the western and central Pacific.