If there is a good feature about ocean noise pollution it is that unlike other human-generated pollutants, once you stop making noise it goes away. This axiom was highlighted last week when the United Nations International Maritime Organization (IMO) adopted a set of noise guidelines that if followed by member nations could decrease low frequency shipping noise by 10dB (ten times less energy) in the next 30 years. This in effect could reverse 10dB increase in shipping noise that has occurred with the expansion of international ocean-borne trade in the last half century.
The increase in shipping noise didn’t exactly sneak up on us; physical oceanographer Donald Ross predicted the increase as far back as 1976 – just as international trade was really beginning to take off. But it wasn’t until the early 1990’s with the deliberate introduction of loud, long-distance communication signals into the ocean that biologists began raising questions about what impacts all of this loud noise might have on marine life. And by then “the camels nose was already well under the tent” – meaning that the sea was already so noisy with ships that there was no possible way to get a biological “baseline” to compare metabolic impacts of this noise on whales, fish, and other sea creatures.
This lack of a baseline problem changed in September 2001, when Susan Parks and Rosalind Rolland (working separately) were both studying North Atlantic Right whales in the Bay of Fundy. When the 9/11 tragedy occurred the US Government halted all shipping in and out of US ports for a week – effectively silencing Atlantic ocean shipping. This incident occurred while Dr. Parks was recording the whales and their habitat, and Dr. Rolland was studying stress hormones in the same whales. This opportunity established a direct correlation between shipping noise and stress.
So we now know that shipping noise causes stress in N. Atlantic Right whales – and by inference it probably causes stress in other marine animals as well. So the IMO guidelines could be a watershed to a less noisy – and a less stressful ocean. This is if member nations follow the guidelines.
But the IMO is only a policy agency, and ocean law is notoriously difficult to enforce. The effectiveness of these guidelines will depend entirely on voluntary participation. Although there are good reasons to believe that at least some nations and ship builders will follow the guidelines, because a quieter ship is a more efficient ship. This bodes well; at least one major source of ocean noise pollution could diminish in the future.
Michael Stocker is a bioacoustician and founding director of Ocean Conservation Research a scientific research and policy development organization focused on ocean noise issues.