Best practice guidelines for sampling and analyses in marine mammal neuroscience: Maximizing the value of studying the nervous system

The marine mammal nervous system provides critical insight into systemic and cognitive health, evolutionary adaptations, and vulnerability to environmental stressors, pollutants, and infectious disease. Nevertheless, neuroscientific data on cetacean nervous systems remain scarce. Comprehensive post mortem analyses including virology, bacteriology, parasitology, neuroimaging, cytoarchitecture, histopathology, toxicology, and molecular biology require timely, systematic, representative sampling due to the brain’s structural heterogeneity and susceptibility to lesions. Rapid decomposition makes a careful assessment of post mortem interval, environmental and geographic conditions, and brain-specific conservation status essential. Regional cell-type-specific and selective neuronal vulnerability to stressors is increasingly recognised in both human and animal brains, underscoring the need for targeted sampling strategies. Recent advances in marine neuroscience leverage state-of-the-art techniques including transcriptomic analyses, induced pluripotent stem cell cultures, and studies of neural, vascular, and glymphatic structures. These highlight the potential to acquire multifaceted information from single specimens. To support this progress, we propose a dual brain-sampling approach consisting of 1) a best-case scenario targeting specific analyses, and 2) a compromise strategy, maximising utility across multiple investigations. A decision-tree framework should ensure representative sampling of brain regions and nuclei while accommodating logistical constraints across specialties. Implementing these standardized guidelines will improve comparability across cetacean neuroscience. As a consequence, this will enhance understanding of neurobiology, pathology, and toxicology, ultimately advancing conservation, comparative neuroscience, and translational research.