Characterizing spatio-temporal patterns of coastal navigation to inform mitigation strategies for conflict between ocean users and the protected humpback whale (Megaptera novaeangliae) in Bahía de Banderas, Mexico

Abstract

Characterizing specific pressures on natural resources is a key component of developing sustainable management strategies. Here we explored the spatiotemporal distribution of marine vessels in a potentially high conflict area between humpback whales and tourism activities, namely Bahía de Banderas, Mexico, from 2017 to 2023. Using high-resolution satellite imagery, we identified high-use areas and their relationship to the presence of urban areas, vessel departure points, and the coastline before, during, and after restrictions put in place during the peak of the COVID-19 pandemic. High-resolution satellite imagery (3m/px - 5m/px) retrieved through the Planet Application Program was used to perform manual detection and annotation of vessels and spatial patterns of marine navigation were characterized through point pattern analyses The spatial distribution of all marine vessel observations in the study area was not random; four high-use coastal areas closer to urban areas were identified, three of which overlap the current marine protected area established to protect whale nursing grounds. Furthermore, as the COVID-19 pandemic began, coastal navigation decreased due to lockdown before picking up again at a higher level than the pre-COVID baseline due to social distancing restrictions. While these changes were not statistically significant, they potentially indicate a behavioral change caused by COVID-19 social distancing recommendations during 2021; the amplified demand for marine vessels appears to have increased the absolute number of vessel chartering and decreased the number of passengers onboard commercial vessels. Our preliminary work provides a reproducible remote sensing methodology that can support future mitigation strategies.