Environment: Seismic oil surveys threaten sea turtles
Posted on November 24, 2015 by Bob Berwyn
Scientists say pro-active mitigation could reduce risk
Marine biologists already know that a number of ocean species are at risk from massive seismic blasting operations used to map oil and gas reserves beneath the ocean floor. A new study by scientists with the University of Exeter warns that seismic surveys may also threaten sea turtles.
The review, published in the journal Biological Conservation, found that compared to marine mammals and fish, turtles are largely ignored in terms of research attention and are often omitted from policy guidelines designed to mitigate the environmental risks of seismic surveys.
Possible ramifications for turtles include behavioral changes and exclusion from critical habitats as well as potential auditory damage, as turtle hearing ranges overlap with airgun frequencies. In addition, turtles become entangled in gear towed behind the survey vessel, which can lead to drowning.
“By talking to oil and gas companies, seismic operators and on-board Marine Mammal Observers, as well as academics and conservationists, we had a great opportunity to gather a broad spectrum of opinions, not just one side of the story. This allowed us to access information that was not available in the published literature,” said Sarah Nelms, with the Centre for Ecology and Conservation at the University of Exeter’s Penryn Campus.
Nelms said more research is needed to fill crucial knowledge gaps that were highlighted by the study.
During a survey, specialized ships simultaneously fire multiple airguns while towing multiple hydrophone streamers, which can cover an area up to 700m wide and 12km long, to capture the returning sound waves.
Researchers involved in the study received reports of turtles becoming entangled in the trailing tail buoys and developed a turtle guard which has been voluntarily installed by some operators. Further research could help make such preventative measures mandatory in the future.
“Seismic surveys are occurring in the waters of at least 50 countries in which marine turtles are present and they are becoming increasingly widespread,” said senior author Professor Brendan Godley, also from the University of Exeter’s Centre for Ecology and Conservation.
“Given the conservation status of turtles, we feel that it is important and timely to assess the level of threat posed by this global activity and highlight knowledge gaps to direct future research efforts … There is a great deal that could be done proactively to help improve the status quo. We are standing by to work with seismic companies and others in the oil and gas sector to this end,” Godley said.
The researchers hope that their findings will assist with the development of policies to minimize the impact of seismic surveys on marine turtle populations, for example ensuring that they are not carried out during sensitive times or in critical areas, such as during breeding seasons or in foraging grounds.