MARINE ECOSYSTEM IMPACTS AND MANAGEMENT RESPONSES UNDER 21ST CENTURY CLIMATE CHANGE

Abstract

Climate change is affecting marine ecosystem structure and function on multiple scales with consequences for ecosystem services, fisheries, and fishery-dependent societies. Projecting future trends and associated uncertainties is important for enhancing understanding of marine processes under climate change, and critical for guiding management and policy at international and national levels. The Fisheries and Marine Ecosystem Model Intercomparison Project (Fish-MIP) represents the first attempt to project marine ecosystem responses to climate change using an ensemble modeling approach, which integrates multiple models to provide a more complete representation of ecosystem processes. Using an ensemble of six global marine ecosystem models within Fish-MIP, I analyzed spatio-temporal changes in marine ecosystems over the 21st century on global to regional scales and evaluated associated challenges for national and international fisheries management. Across major ocean basins, ensemble projections revealed substantial reductions in ecosystem production in most basins except polar, where biomass was projected to increase over the 21st century. Projections across Canada’s Exclusive Economic Zone revealed decreasing ecosystem production in the Canadian Pacific and Atlantic, whereas ecosystem production in the Canadian Arctic increased by 2100, albeit with high projection variability indicating a broad range of potential future trajectories. Ensemble projections within the Northwest Atlantic Fisheries Organization (NAFO) convention area demonstrated regional differences in the direction and magnitude of projected changes. Projected biomass increased in northern NAFO regions, which historically have relatively low fisheries landings, and declined in more southern regions with relatively high historical fisheries landings, such as the Grand Banks off Newfoundland, indicating long-term challenges for management authorities. Across all spatial scales, ecosystem changes were generally higher under the high emissions scenario but could be greatly reduced through climate-change mitigation efforts. Reviewing fisheries management policies and legislations in selected nations highlighted growing evidence that many fisheries are experiencing climate-change impacts, yet mandated climate-change adaptation was not explicitly addressed in any of the reviewed active fisheries management policies and legislations. However, some progress towards climate-informed stock assessments and decision-making was identified. Overall, this thesis uses a state-of-the-art ensemble modeling approach to contribute to a broader comprehension of future trajectories of global and regional climate-change impacts on ocean ecosystems and marine living resources. In addition, the assessment of progress in fisheries management towards integrating climate-change adaptation provides necessary stepping-stones to achieve climate-ready fisheries and fisheries management at multiple institutional scales in a changing ocean environment.