Connections Across Open Water: A Bi-Organelle, Genomics-Scale Assessment of Atlantic-Wide Population Dynamics in a Pelagic, Endangered Apex Predator Shark ().

Large-bodied pelagic sharks are key regulators of oceanic ecosystem stability, but highly impacted by severe overfishing. One such species, the shortfin mako shark (), a globally widespread, highly migratory predator, has undergone dramatic population reductions and is now Endangered (IUCN Red List), with Atlantic Ocean mako sharks in particular assessed by fishery managers as overfished and in need of urgent, improved management attention. Genomic-scale population assessments for this apex predator species have not been previously available to inform management planning; thus, we investigated the population genetics of mako sharks across the Atlantic using a bi-organelle genomics approach.

Genome analysis reveals three distinct lineages of the cosmopolitan white shark.

The white shark (Carcharodon carcharias) (Linnaeus, 1758), an iconic apex predator occurring in all oceans, is classified as Vulnerable globally-with global abundance having dropped to 63% of 1970s estimates,-and as Critically Endangered in Europe. Identification of evolutionary significant units and their management are crucial for conservation, especially as the white shark is facing various but often region-specific anthropogenic threats. Assessing connectivity in a cosmopolitan marine species requires worldwide sampling and high-resolution genetic markers.

Longest recorded migration of a silky shark (Carcharhinus falciformis) reveals extensive use of international waters of the Tropical Eastern Pacific.

Despite being a heavily fished species, little is known about the movements of silky sharks (Carcharhinus falciformis). In this study, we report the longest (in duration and distance traveled) and most spatially extensive recorded migration for a silky shark. This shark, tagged with a fin-mount satellite transmitter at the Galapagos Islands, traveled >27,666 km over 546 days, making two westerly migrations into international waters as far as 4755 km from the tagging location.

Seasonally mediated niche partitioning in a vertically compressed pelagic predator guild.

Niche partitioning among closely related, sympatric species is a fundamental concept in ecology, and its mechanisms are of broad interest for understanding ecosystem functioning and predicting the impacts of human-driven environmental change. However, identifying mechanisms by which top marine predators partition available resources has been especially challenging given the difficulty of quantifying resource use of large pelagic animals. In the eastern tropical Pacific (ETP), three large, highly mobile and ecologically similar pelagic predators (blue marlin (), black marlin () and sailfish ()) coexist in a vertically compressed habitat.