This is the output of GBM (Gradient Boosting Model) analyses of Alexandrium abundance data done by MI OCIS and CoCliME project. This output dataset shows abundance of Alexandrium in present time (1997 - 2016) in SW Ireland. The analyses was performed in R 3.6.3, with the packages tidyverse 1.3.0 for data handling and visualisation, and xgboost 1.2.0.1 for boosted regression analyses. The dataset used for analyses is available on MI data catalogue (http://data.marine.ie/geonetwork/srv/eng/catalog.search#/metadata/ie.marine.data:dataset.4445) and the dataset used for prediction is requested to be included in MI data catalogue ([20]. CDF-t Climate run (Climate_run_corr.rds) in CoCliME model SOP). This dataset is used to visualise the prediction on R Shiny application for present period (https://marine-institute-ireland.shinyapps.io/Alexandrium_abundance/). This dataset is used for displaying present time prediction of Alexandrium abundance on the Shiny app.