Novel deep-sea observations reveal twilight zone occurrence for two species of pelagic sharks: the bignose shark Carcharhinus altimus and the silky shark Carcharhinus falciformis

Studying the behavior of pelagic sharks can be challenging due to the logistical difficulties of locating migratory individuals in the open ocean. This is further compounded by their rarity in certain ocean regions due to overfishing. The accessibility of deep-water basins in The Bahamas provides a unique model system for describing how pelagic sharks connect surface and deep ocean habitats through vertical behavior. Using custom deep-sea landers in The Bahamas, we obtained novel depth data for two species of pelagic sharks: the bignose shark at 767 m and the silky shark at 470 m. These new observations support and corroborate previous vertical niche records for these two species, suggesting that deep diving behavior is likely more common than previously thought and likely important for ecosystem connectivity.