To investigate of the impacts of beach lighting on hatchling predation rate and swimming success during the initial swim away from shore
Type of Study:
The overall predation rate was low (6.9%) and it was not significantly affected by beachfront lighting. However, of those hatchlings leaving lighted beaches that successfully escaped predation, a significantly smaller percentage (32.9%) were able to swim the prescribed distance seawards during the observation period. Moonlight significantly improved the swimming success of hatchlings leaving lighted beaches, particularly when the moon was full, but also significantly influenced predation rates, which were highest during the full moon (12.6%). These results suggest that artificial lights emanating from a landward direction, although not increasing predation measurably, may still interfere with hatchlings’ escape away from the nearshore and into deeper waters, even with natural moon light. Some hatchlings released from dark beaches were attracted by lights from neighbouring beaches once they became visible after hatchlings were a substantial distance from shore.
When rescuing misoriented hatchlings, the hatchling release sites should be evaluated, not only in terms of the level of beachfront lighting adjacentto the beach (the regulations state that they should be released on adjacent dark beaches), but also on the degree of lighting on neighbouring beaches.
Harewood A. & Horrocks J. (2008) Impacts of coastal development on hawksbill hatchling survival and swimming success during the initial offshore migration. Biological Conservation 141, 394-401.