The Biology of Pelagic Fishes in an Era of Climate Change

Pelagic fishes include a diverse range of species that have evolved distinct physiological, behavioral and morphological traits for life in the open-water. Their body size range from less than a centimeter to several meters, yet many share traits such as high swimming performance, efficient respiration and thermoregulation, and a tendency to form schools. Many species undertake large-scale migrations driven by reproduction, foraging, and seasonal environmental changes. Moreover, most marine fishes undertake a pelagic dispersal phase during early stages. Pelagic fishes play a vital role in marine ecosystems, being both predators and prey, and include many species among the most economically important in the world fisheries. Their abundance and distribution are therefore critical for ocean health and global food security. However, they are increasingly threatened by climate change, overfishing and pollution. Because of their mobility, large habitats, morphology and specific adaptations, pelagic fishes are often challenging to study in laboratory settings, limiting our understanding of how they physiologically and behaviorally responses to global threats. Advancing research in this field is thus essential for better management and conservation strategies.

The aim of this Research Topic is to integrate research on the physiology and behavior of pelagic fishes, from small species such as sardines to apex predators like tunas and billfish, to better understand how they cope with climate change. We welcome empirical, methodological and theoretical studies that focus on how pelagic species respond to climate-related stressors, including changes in abiotic factors (e.g. temperature, oxygen) and shift in biotic interactions (e.g. predation, competition, and trophic dynamics). Recent advances in experimental biology, including telemetry, biologging, environmental DNA and controlled laboratory or mesocosm experiments, have increased our capacity to study these wide-ranging species in ecologically relevant contexts. By bridging disciplines and leveraging emerging technologies, this Research Topic aims to highlight research that address knowledge gaps and support the development of sustainable management practices.

We welcome contributions from both original research articles and reviews that advance our understanding of how pelagic fishes respond to climate-related stressors, using physiological, behavioral, ecological and methodological approaches. The scope includes, but is not limited to:

- Ecophysiology of pelagic fishes: Studies focusing on individual- or population-level responses to abiotic and biotic changes focusing on, for example, the cardiovascular physiology, endocrinology and metabolic physiology.

- Behavioral ecology: Research on spatial ecology, foraging strategies, schooling behavior, and habitat selection.

- Life-history strategies: Advances in understanding larval dispersal and recruitment in the context of changing conditions in open water environments.

- Methodological advances: Development and application of tools such as telemetry, biologging, environmental DNA, laboratory and mesocosm experiments, and remote sensing to study pelagic fishes in natural contexts.

- Theoretical and modelling approaches: Predictions of distributional shifts, demographic trends or fish bioenergetics under future climate scenarios.

- Cross-disciplinary studies: Research linking physiology and behavior of pelagic fish across biological scales, from individual to populations and ecosystems for informing conservation and management.