Population connectivity of pelagic megafauna in the Cuba-Mexico-United States triangle

Jay R Rooker,Richard T Kraus,J Marcus Drymon,R J David Wells,Neil Hammerschlag,Brett J Falterman,Jill M Hendon,Barbara A Block,David H Secor,Matthew J Ajemian,Eric R Hoffmayer,Michael A Dance,Jennifer A Mckinney,James S Franks,Gregory W Stunz,Michael R Castleton,John F Walter

doi:10.1038/s41598-018-38144-8

Abstract

The timing and extent of international crossings by billfishes, tunas, and sharks in the Cuba-Mexico-United States (U.S.) triangle was investigated using electronic tagging data from eight species that resulted in >22,000 tracking days. Transnational movements of these highly mobile marine predators were pronounced with varying levels of bi- or tri-national population connectivity displayed by each species. Billfishes and tunas moved throughout the Gulf of Mexico and all species investigated (blue marlin, white marlin, Atlantic bluefin tuna, yellowfin tuna) frequently crossed international boundaries and entered the territorial waters of Cuba and/or Mexico. Certain sharks (tiger shark, scalloped hammerhead) displayed prolonged periods of residency in U.S. waters with more limited displacements, while whale sharks and to a lesser degree shortfin mako moved through multiple jurisdictions. The spatial extent of associated movements was generally associated with their differential use of coastal and open ocean pelagic ecosystems. Species with the majority of daily positions in oceanic waters off the continental shelf showed the greatest tendency for transnational movements and typically traveled farther from initial tagging locations. Several species converged on a common seasonal movement pattern between territorial waters of the U.S. (summer) and Mexico (winter).

Highlights

Large pelagic fishes are common apex predators in coastal and open ocean ecosystems[1,2] and play important roles in structuring marine communities through top-down control[3,4]
This species is capable of long-distance displacement (>1000 km), movement was largely restricted to the Gulf of Mexico (GoM) and the passageways connecting this basin to the Atlantic Ocean
International crossings by pelagic predators tagged in the U.S GoM occurred for most of the species investigated with varying levels of bi- or tri-national population connectivity displayed by billfishes, tunas, and sharks

Summary

Introduction

Large pelagic fishes are common apex predators in coastal and open ocean ecosystems[1,2] and play important roles in structuring marine communities through top-down control[3,4]. Conservation and rebuilding efforts for key constituents of the pelagic fish assemblage (e.g., billfishes, tunas, and sharks) requires species-specific information on movements (i.e., spatial displacements) necessary for individuals to complete their life cycles[5,6]. Billfishes, tunas, and sharks are common components of the pelagic ecosystem in the GoM15–17, and the territorial waters of the three countries serve as critical spawning, nursery, and/or foraging habitat for multiple species within each taxonomic group[18,19,20] Conservation measures for these pelagic predators vary spatially across the GoM7,10, with each country displaying different levels of cooperation in fishery organizations responsible for their management. The primary goal of this investigation was to quantify the timing and prevalence of international crossings displayed by each species as well as identify areas of high exchange or crossing hotspots

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Conclusion