Sex-specific feeding ecology and microplastic ingestion in smooth hammerhead shark (Sphyrna zygaena) from the eastern tropical Pacific Ocean: insights from stable isotope and fatty acid signatures.

Microplastic pollution threatens marine life, especially apex predators like sharks that ingest these particles through their prey. The smooth hammerhead shark (Sphyrna zygaena), an endangered species, remains understudied in terms of microplastic exposure. This study examines whether sex-specific foraging ecology influences microplastic ingestion in S. zygaena from the eastern tropical Pacific. We characterized microplastics in the posterior part of the pylorus and used stable isotope and fatty acid analyses to compare dietary patterns between sexes. Results indicate that while the abundance of ingested microplastics did not differ between sexes, males ingested a wider variety of particle types, polymers, and sizes. Stable isotope and fatty acid profiles revealed that males display greater temporal variation in diet and lower trophic niche overlap across tissues compared to females, suggesting a more dynamic foraging strategy. These findings imply that sex-specific foraging behavior might be a key factor influencing the diversity of microplastic exposure in marine predators, rather than the total quantity ingested.