Climate Change Alters Feeding Areas for Highly Migratory Species

Jenn Hoskins
12th May, 2025

Climate Change Alters Feeding Areas for Highly Migratory Species

Data from tagged juvenile albacore (Thunnus alalunga) reveal that extensive migrations across the North Pacific (C) facilitate peak energy ingestion (A) and positive net energy balances (B) primarily during the productive spring and summer seasons.

Image adapted from: Muhling et al. / CC BY (Source)

Key Findings

  • *North Pacific Study:* Warming oceans are shrinking some tuna habitats but creating new, productive colder areas for juvenile albacore tuna
  • *Migration Shifts:* Tuna may move towards coastal areas with better food resources as offshore regions become less suitable
  • *Advanced Modeling:* The new approach, which includes energy use and feeding opportunities, provides more accurate predictions of tuna movements under climate change
Climate change is reshaping marine ecosystems, altering the distribution and movement patterns of mobile marine organisms. Understanding these changes is crucial for predicting the future of marine biodiversity and fisheries. Traditional methods, like statistical species distribution models, often rely on correlating past patterns with environmental factors to forecast future shifts. However, these models can fall short when faced with unprecedented environmental conditions or when they overlook the underlying biological processes that drive species' habitat use. A recent study conducted by researchers at the University of California, Santa Cruz[1] addresses these limitations by integrating laboratory measurements, field observations, and environmental data to examine the energetic landscapes, or "energetic seascapes," of juvenile North Pacific albacore tuna (Thunnus alalunga). Albacore tuna are among the most migratory finfish, undertaking extensive journeys across the Pacific Ocean. Despite their economic and ecological importance, the impact of climate-driven habitat changes on their migrations remains poorly understood. The research team developed a framework using Generalized Additive Models to analyze how energy gain and loss in albacore tuna are influenced by ocean conditions. By applying this framework to projections from various earth system models, the study quantified changes in both thermal and foraging habitats from the historical period (1971–2000) to the future (2071–2100). This approach allowed the researchers to move beyond simple temperature correlations and consider the complex interactions between environmental factors and the physiological needs of the tuna. One of the key findings of the study is that albacore tuna migrate seasonally between feeding grounds in the California Current System and the offshore North Pacific, with peak foraging success occurring in spring and summer. The migration pathways largely align with regions where the metabolic costs of movement are minimized, highlighting the importance of energy efficiency in these long-distance migrations. This aligns with the resource tracking concept discussed in earlier research, which suggests that animals optimize their movements to maximize energy gain by following resource availability across space[2]. The study also revealed that future warming is likely to result in a loss of favorable thermal habitats in the subtropics, potentially reducing the overall habitat area available to albacore tuna. However, this loss may be offset by increased access to productive and energetically favorable sub-arctic ecosystems. Interestingly, while temperature projections indicate a contraction in suitable habitat, the availability of high-quality foraging areas in the remaining habitats could mitigate some of these losses. This nuanced understanding underscores the importance of considering multiple environmental factors, not just temperature, when assessing the impacts of climate change on marine species. Furthermore, the research suggests that coastal foraging areas may become more energetically favorable in the future, whereas offshore foraging grounds might decline in suitability. This shift could influence the migratory routes and behaviors of albacore tuna, as they seek out areas that offer the best balance of energy expenditure and resource availability. These findings resonate with the green wave hypothesis explored in terrestrial systems, where migratory animals track phenological changes in high-quality forage[3]. Although blue whales in marine systems have been shown to rely more on the memory of long-term average conditions rather than immediate environmental cues[3], albacore tuna appear to adapt their movements based on both historical and current resource dynamics. Incorporating energetic seascapes into the analysis provides a mechanistic understanding of how climate change affects migratory species. This approach builds on previous work that emphasizes the role of energy balance in shaping animal movements. For instance, studies on Pacific bluefin tuna have demonstrated how metabolic rates are influenced by ambient water temperatures, highlighting the importance of thermal niches for energy efficiency[4]. By integrating similar physiological insights, the current study offers a more comprehensive view of the factors driving albacore tuna migrations. Additionally, the study touches on the role of predators in the open ocean, where subsurface light conditions influence trophic interactions. Previous research has shown that large predators optimize their foraging strategies by targeting both shallow and deep scattering layers, which vary in productivity across different marine biomes[5]. Understanding how albacore tuna navigate these energetic landscapes complements our knowledge of predator-prey dynamics in the ocean and their responses to changing environmental conditions. The findings from the University of California, Santa Cruz study highlight the importance of moving beyond temperature as the sole predictor of habitat suitability. By considering the energetic costs and benefits associated with different foraging and migratory behaviors, researchers can develop more accurate models of how marine species will respond to climate change. This comprehensive approach not only enhances our ecological understanding but also has practical implications for fisheries management and conservation efforts. In conclusion, the integration of energetic seascapes into species distribution models represents a significant advancement in predicting the impacts of climate change on migratory marine organisms. The study of juvenile North Pacific albacore tuna demonstrates how combining physiological data with environmental projections can provide deeper insights into the future of marine ecosystems. As climate change continues to alter the world's oceans, such mechanistic approaches will be essential for safeguarding the resilience and sustainability of highly migratory species and the broader marine environments they inhabit.

EcologyOceanographyMarine Biology

References

Main Study

1) Climate change impacts to foraging seascapes for a highly migratory top predator

Published 9th May, 2025

https://doi.org/10.1186/s40462-025-00558-1

Related Studies

2) Emerging Perspectives on Resource Tracking and Animal Movement Ecology.

https://doi.org/10.1016/j.tree.2020.10.018

3) Memory and resource tracking drive blue whale migrations.

https://doi.org/10.1073/pnas.1819031116

4) Temperature effects on metabolic rate of juvenile Pacific bluefin tuna Thunnus orientalis.

Journal: The Journal of experimental biology, Issue: Vol 210, Issue Pt 23, Dec 2007

5) A shallow scattering layer structures the energy seascape of an open ocean predator.

https://doi.org/10.1126/sciadv.adi8200


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