Vessel speed increases collision risk for the green turtle Chelonia mydas

  • Published source details Hazel J., Lawler I.R., Marsh H. & Robson S. (2007) Vessel speed increases collision risk for the green turtle Chelonia mydas. Endangered Species Research, 3, 105-113.


This study is summarised as evidence for the following.

Action Category

Limit vessel speeds

Action Link
Reptile Conservation
  1. Limit vessel speeds

    A replicated study in 2004 in shallow oceanic water off the coast of Queensland, Australia (Hazel et al. 2007) found that green turtles Chelonia mydas were more likely to flee a vessel driven at slower speeds. Of 1,819 turtle encounters when the turtle was on the sea floor, 60% were able to flee a slow-moving boat (416 of 694 turtles fled), 22% at a moderate speed (136 of 620 turtles fled) and 4% at a fast speed (20 of 505 turtles fled). This trend was statistically significant only when turtles were within 6 m offset of the vessel (see original paper). Turtles in the water column or on the surface also tended to show a reduced flight response at faster vessel speeds (small sample size precluded statistical analysis, see original paper). A 6 m aluminium boat with a 40 hp outboard motor was driven at three speeds (4, 11 and 19 km/h) on a transect 5 km parallel to the shoreline about 200–450 m from the shore in <5 m of water in the 3 hours before and after noon. The behaviour of turtles sighted within 10 m of the boat were recorded by a spotter.

    (Summarised by: Maggie Watson, Katie Sainsbury)

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