Modelling the past and the future effects of climate and exploitation on the population dynamics
and distribution of skipjack tuna
Sibylle Dueri
The APECOSM-E (Apex-Predator-ECOSystem-Model – Estimation) model represents the distribution
and population dynamics of skipjack tuna under the joint effects of climate and fisheries. The model,
structured in 3D space and fish size, uses the environmental forcing (3D temperature, oxygen,
meso-zooplankton and marine current fields generated by the coupled physicalbiogeochemical ocean model NEMO-PISCES) to simulate physiological rates of tuna
(reproduction, growth, natural mortality) and habitat gradients that drive the horizontal and vertical
movements of tuna. Observed, spatially explicit fishing effort data are used to determine the fishing
mortality.
The first part of the talk will focus on the application of the model to the Indian Ocean skipjack tuna
population and will present the maximum-likelihood parameter estimation that was accomplished
using historical data of fisheries. Then we will explore the long term dynamics of skipjack tuna
populations at the global scale under the effect of climate change, using forcing fields from the IPSLCM5 Earth System Model for the global warming scenario RCP8.5.