Datasets associated the West Pacific skipjack tuna project

This Zenodo record contains source and derived datasets used to investigate how oceanographic variability, ENSO, the Interdecadal Pacific Oscillation (IPO), and long-term climate change affect skipjack tuna (Katsuwonus pelamis) biomass in the western and central Pacific Ocean. The analysis covers approximately 120°E–240°E and 20°S–20°N over 1960–2022. Skipjack biomass was obtained from a SEAPODYM simulation and aggregated into larval, juvenile, and adult life stages. Generalized additive models were used to relate absolute biomass and biomass anomalies to spatially varying oceanographic predictors. Complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) was used to separate high-frequency, interannual, decadal, and long-term components of environmental variability. The resulting components were analysed against ENSO, the IPO, and atmospheric CO₂. The record contains the following files: absolute_values_SEAPODYM_WCPO.txt: comma-separated table containing absolute seasonal skipjack biomass and coincident oceanographic predictors at each model grid location in the western and central Pacific Ocean. anomalous_values_SEAPODYM_WCPO.txt: comma-separated table containing the corresponding skipjack biomass and oceanographic anomalies used in the GAM analyses. Both tabular datasets include spatial, temporal, life-stage biomass, and environmental-predictor fields. ONI.txt: Oceanic Niño Index time series used to represent ENSO variability. Tripolar_IPO.txt: Tripole Pacific Index time series from NOAA. PDO.txt: Pacific Decadal Oscillation time series from NOAA. derived_IPO.nc: processed IPO index used in the decadal-variability analysis. CO2.txt: atmospheric CO₂ concentration time series used as an indicator of long-term anthropogenic climate forcing. effect_ENSO_on_Skipjack_allpredictors.nc: gridded GAM-derived changes in skipjack biomass associated with a positive one-standard-deviation ENSO perturbation. Separate variables represent effects transmitted through upper-layer temperature (T_L1), sea-surface temperature (SST), deeper-layer zonal velocity (U_L3), second-layer oxygen (O2_L2), euphotic-zone depth (ZEU), and second-layer temperature (T_L2). effect_IPO_on_Skipjack_allpredictors.nc: equivalent gridded biomass-effect fields associated with a positive one-standard-deviation IPO perturbation. effect_CC_on_Skipjack_allpredictors.nc: equivalent gridded biomass-effect fields associated with a 100 ppm increase in atmospheric CO₂, estimated from the long-term components of the predictors and GAM-derived biomass responses. The three effect datasets are model-derived diagnostics rather than direct observations. They quantify the spatially varying skipjack biomass response associated with each environmental pathway under the specified climate perturbation. The analysis and figure-generation code is available at: https://github.com/pearseb/Skipjack_SPC_paper