Feasibility assessment of bioclimate vulnerability approaches for priority marine migratory species in the Caribbean and Pacific UK Overseas Territories

Services Project Aims To assess the feasibility of applying bioclimate vulnerability assessment approaches to priority marine migratory species within the Caribbean UK Overseas Territories and the Pitcairn Islands. Building on previous work undertaken for JNCC, the study will evaluate the suitability of the proposed bioclimate vulnerability approach, consider relevant alternative approaches where appropriate, and determine whether sufficient evidence, data and expertise exist to support future implementation. 4. Project Background Climate change is increasingly affecting marine migratory species through changes in sea temperature, ocean productivity, habitat availability, ocean circulation patterns, species interactions and the frequency and intensity of extreme weather events (IPCC, 2022; Martay et al., 2023). These pressures may alter species distributions, abundance, migration routes and ecological relationships, with potentially significant consequences for biodiversity, ecosystem services and economies across the Caribbean Overseas Territories (OTs) and the Pitcairn Islands (IPCC, 2022; Martay et al., 2023). Evidence from marine vertebrates indicates that climate-driven changes in ocean conditions can alter migration timing, migratory routes, species distributions and access to suitable feeding and breeding habitats through changes in environmental conditions and prey availability (Kuletz et al., 2024). However, considerable uncertainty remains regarding how priority marine migratory species are likely to respond to future climate conditions and what these changes may mean for conservation and management (Martay et al., 2023). Previous JNCC work has reviewed available evidence on climate impacts affecting marine migratory species and identified a suite of priority species for further investigation. This work also highlighted the potential application of bioclimate vulnerability assessment approaches, which seek to combine information on species ecology, environmental change and climate pressures to better understand species vulnerability under future climate scenarios. However, uncertainty remains regarding the suitability of these approaches for the priority species and Territories, the data required to support their application, and whether resulting outputs would be sufficiently robust to inform management and decision-making. Previous work undertaken for St Helena, by Strathclyde University, explored ecosystem-based bioclimate vulnerability assessment approaches to project biomass declines in the marine protected area food web due to climate change (Olher et al., 2026). This study should consider the extent to which this and similar approaches may be applicable to priority species within the Caribbean Overseas Territories and Pitcairn. While bioclimate vulnerability assessments represent a promising approach, a range of alternative methods of assessing ecological/biological impacts of climate change may also be relevant. These vary in their assumptions, data requirements, technical complexity, resource needs and intended applications. It is therefore important to understand whether the proposed bioclimate vulnerability approach represents the most appropriate option for the priority species and Territories, and whether sufficient evidence exists to support its implementation. However, the primary purpose of this study is to assess the feasibility of applying a suitable bioclimate vulnerability approach to priority marine migratory species, and new geographies, rather than to undertake a comprehensive review of assessment methodologies. Consideration of alternative approaches should therefore be targeted and proportionate, focusing on whether an alternative method would offer a materially stronger basis for future implementation. The next phase of work is therefore to undertake a feasibility assessment that builds on previous work while critically evaluating the suitability of the proposed approach in comparison with other relevant assessment methods. This will include reviewing methodological requirements, assessing the availability and suitability of biological, ecological, environmental and climate datasets, identifying key evidence gaps and technical constraints, and determining the level of confidence that could be achieved through future assessments. The study will provide an evidence-based assessment of the most appropriate approach or approaches for application to priority marine migratory species, what analyses could be undertaken using currently available information, and what additional data, expertise or investment would be required to support future implementation. The findings will inform future implementation decisions and provide a roadmap for any subsequent climate vulnerability or bioclimate vulnerability assessment programme, supporting climate adaptation, marine conservation and environmental decision-making across the Caribbean Overseas Territories and the Pitcairn Islands. 5. Project Objectives To meet the overall aims of this project (Section 2), the objectives are: Objective 1 Review the proposed bioclimate vulnerability assessment approach and assess its suitability for application to priority marine migratory species within the Caribbean Overseas Territories and the Pitcairn Islands. Objective 2 Compare the proposed approach against a limited number of relevant alternative assessment approaches and identify the most appropriate option(s) for future implementation. Objective 3 Assess the feasibility of implementing the recommended approach for a priority list of marine migratory species supplied by JNCC. Objective 4 Identify key evidence gaps, data limitations, uncertainties and resource requirements associated with future implementation. Objective 5 Develop recommendations and an implementation roadmap for any future climate vulnerability or bioclimate vulnerability assessment programme.