Reproductive timing and putative mating behavior of the oceanic whitetip shark Carcharhinus longimanus in the eastern Bahamas

Abstract

Oceanic whitetip sharks Carcharhinus longimanus aggregate at Columbus Point, Cat Island, The Bahamas, in at least April and May. We show that signs of putative mating activity (i.e. bite wounds) on mature females, which dominate the aggregation, are exceedingly rare at that time, but may be more common in July. Male plasma testosterone concentrations also suggest that spermatogenesis occurs in April and May and copulation is underway or has just ended by July. We support these preliminary data with direct observations of putative precopulatory behavior made at Columbus Point in July 2019. Using 25 min of video footage from the event, we identify common shark mating behaviors such as echelon or parallel swimming, following, shielding, nosing, and biting. We also describe the ‘circle-back’, a newly observed behavior where the male orients to the trail of the female, possibly to investigate olfactory cues. Based on these 3 parallel lines of evidence, we hypothesize that mating could occur in the eastern Bahamas as early as May, but is probably concentrated in midsummer (i.e. July), and that Columbus Point, Cat Island, may be a mating habitat for the oceanic whitetip shark.

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