Dolphins, Tourism and the Hidden Cost of Disturbance

New insights into dolphin reproduction from 15+ years of monitoring

The northern Red Sea is home to both a busy tourism industry and a resident population of Indo-Pacific bottlenose dolphins (Tursiops aduncus). Could changes in tourism affect dolphin reproduction?

Long-term observations by the Dolphin Watch Alliance gave us a rare opportunity to explore this question. We followed around 470 individually identified dolphins and reconstructed the timing of approximately 200 births between 2006 and 2025. Because calves are not always seen immediately after birth, their approximate birth months were estimated from their development, behaviour, and repeated observations of the calf and its mother, rather than simply counting calves first seen in a particular year.

Dolphins appear able to maintain reproduction despite the overall growth and fluctuations in tourism. But when tourism was unusually high or unusually low, we saw a different pattern: births tended to change about one year later. Lower-than-expected tourism was followed by more births than expected, suggesting that changes in human activity may affect reproduction.

The one-year delay is particularly interesting because it could point to an effect around the time of conception. However, this study shows a relationship, not proof of cause and effect. Tourism itself may not be the problem — how tourism is carried out, including boat traffic, crowding and disturbance around dolphins, may be more important.

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