A new set of guidelines for shipping companies addresses underwater noise pollution for the first time. The rules, created by the International Maritime Organization, are meant to curb the rumblings of massive ships that ply oceans around the world, the New Scientist reports. At this point, the rules are voluntary, but individual companies or states have the options of making them mandatory.

The "Adoption of the Code on Noise Levels on Board Ships" annex is meant to help alleviate the problem of noise-induced harm to sea life. As the New Scientist explains, studies have linked man-made noise to both dolphin strandings and higher stress levels in whales. Other creatures, including octopuses and squids, also seem to suffer some detrimental repercussions when too much noise invades their habitats. New Scientist:

The guidelines include recommendations to make shipping quieter, especially targeted at propellers as they make the most noise. "The focus is on reducing propeller cavitation, the creation and destruction of tiny bubbles that create a real roar in the water," says [Michael] Jasny [of the National Resources Defense Council]. "The guidance recommends measuring and minimising the noise in newly built ships and reducing it in existing ones."

Avoiding noise also avoids wasting energy, so helps companies save fuel. "It makes compliance a win-win situation for whales and shippers," says Jasny.

Some conservationists are complaining, however, that the new rules, which don't cover military vessels or sonar, aren't enough. However, as Jasny points out in his own blog, the new rules are only the beginning. "We will have to work with shipping lines, ports, ship classification societies, and governments to put the guidelines into practice and begin pushing back against this worsening global problem," he writes. "But yesterday was a milestone."