Who’s Minding the Makos? Applications of Movement Patterns and Habitat Utilization for Management of Shortfin Mako Shark and Intersection with Offshore Energy Exploration

• Main Author: Manz, Maria H
• Format: Text
• Language: English
• Published: DigitalCommons@URI 2021
• Subjects: Biological oceanography; Block Island; North Atlantic; Northwest Atlantic
• Online Access: https://digitalcommons.uri.edu/dissertations/AAI28716216

The absence of coordinated international management for shortfin mako sharks (Isurus oxyrinchus, hereafter: mako) in the Northwest Atlantic Ocean and the Gulf of Mexico, coupled with a lack of knowledge about large-scale mako movements and habitat use, have hampered effective mako shark management in the North Atlantic (Campana, 2016). In addition to fishing pressure, anthropogenic factors like the expansion of oil rigs into deeper pelagic waters and development of offshore wind farms in the Northwest Atlantic are likely to influence mako habitat use (Bailey, Brooks, and Thompson, 2014). Our work used a longitudinal satellite telemetry dataset to investigate the movement patterns of 60 mako sharks in relation to a suite of human interactions, including jurisdictional boundaries, management measures, and energy exploration in the western North Atlantic and Gulf of Mexico. Altogether, mako sharks visited 27 different Exclusive Economic Zones in the North Atlantic Ocean. Sharks tagged off the U.S. showed seasonal and behavioral influences in their transboundary movements, as well as potential demographic deviances. Sharks tagged off of Mexico showed less variability in their transboundary movements as a response to season and movement behavior. Current U.S. management strategies provide insufficient protection for the North Atlantic shortfin mako stock. We found, the degree of overlap between the shark's core area and existing oil rigs to be negligible, and offshore oil rigs and the Block Island Wind Farm did not significantly affect shark movement behavior. However, we show that the proposed locations of offshore wind farms are within a highly utilized area for mako sharks in the western North Atlantic. Our study emphasizes the need to implement cooperative international management and improvement in U.S. management strategies to facilitate the recovery of the North Atlantic shortfin mako stock. In addition, we highlight the need to develop a deeper understanding of offshore wind farms' effect on mako sharks and other highly migratory species.