Acoustic Sanctuaries for Marine Mammals
Imagine living in an environment of constant noise where you cannot get anything accomplished. Ocean noise pollution caused by shipping, oil and gas development, and other human activities is making this the reality for marine mammals in many places, interfering with their ability to detect prey and communicate with one another. Yet some areas of the ocean remain refuges of quiet. A new study has identified some of these acoustic sanctuaries off the coast of British Columbia in the hope that they may be protected.
The study, which was published in Marine Pollution Bulletin, identifies these quiet spaces as “opportunity sites.”
“They represent places where we could protect animals simply by maintaining the status quo,” Rob Williams, lead author of the study, told Mongabay. Williams, a marine conservation biologist, is co-founder of the research nonprofit Oceans Initiative, which is based in Seattle and Alert Bay, British Columbia.
One challenge to identifying and preserving these environments is that marine mammals differ in where they live and in their sensitivity to noise. “[E]ach species has different distribution and habitat preferences within a country’s territorial waters, and different species with different hearing anatomy will hear the same sound differently. What is noisy to one species may seem quiet to another,” Williams said in an email.
For the study, he and his co-authors developed detailed maps showing how risk from noise varies across the region for 10 marine mammal species living there. To do this, they drew on existing research describing ship traffic patterns to predict ambient noise levels, as well as literature on the distribution and hearing sensitivity of the 10 species.
Maps from the study show the Pacific coast just north of Vancouver displaying quiet zones for fin whales (Balaenoptera physalus), minke whales (B. acutorostrata), humpback whales (Megaptera novaeangliae), killer whales (Orcinus orca), Pacific white-sided dolphins (Lagenorhynchus obliquidens), harbor porpoises (Phocoena phocoena), Dall’s porpoises (Phocenoides dalli), Steller sea lions (Eumetopias jubatus), northern elephant seals (Mirounga angustirostris), and harbor seals (Phoca vitulina).
The authors emphasize that these opportunity sites can be protected with little change to current shipping patterns, which makes them a relatively easy target for conservation. “We do not intend to minimize the amount of work that it will take to make noisy areas quieter. But one of the lessons learned from other pollution-prevention exercises is that it pays to start with so-called ‘low-hanging fruit’,” the authors write.
Continue reading at ENN affiliate, MONGABAY.COM.
Sea lion image via Shutterstock.