Potential distribution of critically endangered hammerhead sharks and overlap with the small-scale fishing fleet in the southern Gulf of Mexico

Abstract

Understanding the degree to which fishing operations overlap with the distribution of exploited populations is essential for population assessments and in the formulation of management measures. Here we used ecological niche models to estimate hammerhead sharks’ potential distribution that allowed the first assessment of their overlap with small-scale fishing operations in the southern Gulf of Mexico (GOM). The models were better than random models, with bathymetry as the most important predictor variable for bonnethead shark and average Chl-a for scalloped and great hammerheads. Shallow and intermediate waters of the GOM are of high environmental suitability for bonnethead shark and great hammerhead, and intermediate and deep waters within the continental shelf are more suitable for scalloped hammerhead. The spatial distribution of the small-scale fleet that operates on the western Yucatán Peninsula, southern GOM, had a high overlap with the estimated high environmental suitability of both bonnethead and great hammerhead sharks. We highlight the bonnethead shark, since its coastal habitat preference spans all ontogenetic stages, thus making it highly vulnerable to coastal anthropogenic impacts, including several small-scale fisheries.