The implications of climate change for New Zealand’s freshwater fish

Data from:Canning, Zammit, Death. (2024). The implications of climate change for New Zealand’s freshwater fish. Canadian Journal of Fisheries and Aquatic Sciences.Abstract:Climate change is poised to reshape ecological communities globally by driving species into new environments and altering interactions between species. Conservation efforts should not only address current pressures but also plan for future pressures, such as sensitive species moving into degraded environments or arising problematic trophic interactions. This study sought to assess how climate change may affect the end-of-century distributions of New Zealand’s native and non-native freshwater fish, including consequences for the overlap between trout (a non-native sports fish) and native species vulnerable to trout predation. Random forest modelling was used to predict end-of-century distributions for New Zealand’s freshwater fish based on six hydrologically downscaled global climate models across four representative concentration pathways. Severe climate change impacts could drive nine native fish species to extinction or near-extinction and cause substantial declines in another eight native species. Seven non-natives are also predicted to decline substantially, including a 30-40% reduction in the extent of trout. To avert these potential extinctions, it is crucial to mitigate climate change severity and improve land use impacting freshwater ecosystems.Word Document: 'cjfas-2024-0127' suppla contains Supplementary material A.Excel file: 'cjfas-2024-0127supplb' contains Supplementary material Bcsv file: 'Optimal_Thresholds' contains the probability thresholds that maximised the Kappa statistic when determining presence from probability of occurrence.csv file: 'All preds RF wide' contains the probability of occurrence for all species at all river reaches modelled. Data is in wide format with columns representing individual species, along with a 'Scenario' column indicating the RCP climate, 'Model' column indicating the global circulation model used, and 'nzsegment' indicating the river reach as defined in the New Zealand River Environment Classification system v2.4.csv file: 'All preds binary RF wide' contains the presence (1) or background (0) classification for all species at all river reaches modelled. Data is in wide format with columns representing individual species, along with a 'Scenario' column indicating the RCP climate, 'Model' column indicating the global circulation model used, and 'nzsegment' indicating the river reach as defined in the New Zealand River Environment Classification system v2.4.