Effects of diving on sea turtles: boat strikes near Mabul Island
Recreational diving has the potential to both positively or negatively affect sea turtles and other marine life, and the awareness of the diver may play an important role.
An example where sea turtles can be negatively impacted by diving is boat strikes.
At the International Sea Turtle Symposium 2017, there was a particularly interesting study related to the effects of boat strikes on Green Sea Turtles near Mabul Island, off the east coast of Sabah in Borneo. Mabul has a high traffic of tourists, many of whom visit the island for diving.
Green sea turtles were surveyed from 2013 to 2016, and boat strike injuries on these turtles were categorized into ‘straight cuts’, ‘parallel cuts’, ‘blunt injuries’, and ‘deep incisions’.
A total of 318 individual green turtles were caught, and over 10% (!) of these turtles had injuries from boat strikes, 9% of which (0.9% in total) had either very deep wounds or had died from the strikes.
A solution is to reduce the speed of boats to 4 km/h in order to provide sufficient time for sea turtles to escape, especially at the shallow reef areas.
It may be worth looking into the effects of boat strikes from dive boats locally in Okinawa, given the popularity of diving and ubiquity of dive shops on the island, in order to understand what effects we may have on the marine life here and come up with solutions to alleviate it. It is highly likely that Okinawa faces a similar problem, as even if dives sites are located at deeper waters, sea turtles still need to surface frequently in order to breath.
This study was conducted by Jiun Lang Phu (Jonathan) and Pushpa Palaniappan, at the Borneo Marine Research Institute.