Cetacean Ecology and Fisheries Interactions

Cetaceans occupy pivotal roles in marine ecosystems as apex or mesopredators, influencing trophic structure, nutrient cycling and prey community dynamics. Their foraging behaviour, energy requirements and habitat preferences are shaped by prey availability and oceanographic conditions, yet these same attributes lead to complex interactions with human fisheries. Dolphins, porpoises and whales may remove catch directly from nets and lines—a phenomenon known as depredation—while also suffering unintended capture, or bycatch, in fishing gear. These interactions can alter cetacean foraging strategies, affect fish stock assessments and generate significant economic losses for fishers. Overlapping distributions of fishing effort and key cetacean habitats, coupled with changing prey distributions under climate variability and overfishing, exacerbate conflicts. Effective management thus requires an integrated understanding of cetacean diet, movement patterns and behavioural responses to gear, alongside socio-economic considerations and mitigation technologies. This synthesis highlights global case studies, delineates drivers of interaction and examines emerging approaches to reduce harm to both marine mammals and fisheries.

Research from Nature Portfolio

Recent studies have elucidated selective foraging by a critically endangered baleen whale in a heavily industrialised gulf. By coupling Bayesian mixing models of stable isotope ratios with assessments of prey energy density, researchers demonstrated that this species targets schooling fish offering the highest calorific return rather than the most abundant prey. This finding underscores the importance of prey quality in shaping cetacean feeding ecology and highlights potential vulnerability to environmental change that alters the energy composition of key forage species.

Cetacean Ecology and Fisheries Interactions publication trend

The graph below shows the total number of articles in cetacean ecology and fisheries interactions across all publications each year (not limited to Nature Index journals).

Technical terms

Depredation: Removal of fish by cetaceans directly from fishing gear, resulting in lost catch and often gear damage.

Bycatch: Unintentional capture of non-target marine species in fishing operations, with potential for injury or mortality.

Catch-Per-Unit-Effort (CPUE): A standardised measure of fishery yield, expressed as catch mass or number per unit of fishing effort, used to infer stock abundance or depredation impact.

Stable Isotope Analysis (SIA): A technique that measures ratios of heavy to light isotopes in tissues to reconstruct dietary composition and trophic position over time.

Bayesian Mixing Model: A statistical framework that combines isotope data with prior information to estimate proportional contributions of different prey to a consumer’s diet.

References

1. Critically endangered Rice’s whales (Balaenoptera ricei) selectively feed on high-quality prey in the Gulf of Mexico. Scientific Reports (2023).
2. Questionnaire and experimental surveys show that dolphins cause substantial losses to a gillnet fishery in the eastern Mediterranean Sea. ICES Journal of Marine Science (2022).
3. Understanding the Interactions Between Cetaceans and Other Megafauna With the Albacore Tuna Fishery: A Case Study From the Cyprus’ Pelagic Longline Fishery. Frontiers in Marine Science (2022).