First observation on the mating behaviour of the endangered scalloped hammerhead shark Sphyrna lewini in the Tropical Eastern Pacific
Here we provide a detailed analysis of the first complete sequence of a mating event for the endangered scalloped hammerhead shark, Sphyrna lewini. This analysis is based on a mating event recorded at Isla del Coco National Park, Costa Rica, where large schools of hammerhead sharks are frequently encountered. S lewini mating sequence can be characterized by: (1) an open water encounter, (2) pre-copulatory biting, (3) grabbing of pectoral fin/copulation, (4) free fall, (5) separation and (6) following. Based on this single observation we found that only one male appears to be involved in a copulation cycle and that mating took place in a high current zone potentially to favor respiration when both individuals are unable to swim. This observation highlights the difficulty in observing mating behavior for this species since mating is likely to occur in open waters.
KeywordsHammerhead shark Reproduction ETP Conservation
We thank the Undersea Hunter Group for allowing us to use this underwater video footage for our analyses and dive guide Wilson Cadavid for all the valuable information. We also thank to the crew of M/V Argo their helpful comments on this manuscript. We are grateful to the Helsmley Charitable Trust for their financial support. We are grateful to Ana Victoria Moya and Florencia Cerutti for their valuable comments to previous versions of this manuscript. This is contribution number 2176 from the Charles Darwin Foundation.
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