I’m not sure the latest wayward marine mammal has made the national headlines, but in and around the greater San Francisco Bay Area a bottlenose dolphin 90 miles from sea has caught the attention of Californians. Similar incidents happen every so often and within the last year and a half have included a couple of humpback whales and a few sea lions that have veered off their ocean courses and navigated the delta and river system.
Well, hearing that story prior to a late night walk sparked a conversation that eventually evolved into contemplation about unexplained marine mammal behaviors such as strandings. Perhaps it was not necessarily a dialogue but more like a brainstorming session or spoken tag cloud bringing together species, strandings, research, and theories. And a post-walk news search turned up, ironically, a very recent Jan 13, 2009 article highlighting a ruling that would allow the U.S. Navy to continue training with sonar and bombs in Hawaiian waters. The catch, tongue in cheek, is that the Navy must try to protect whales and other marine animals from the harmful effects. Additionally, the chain of coincidences continued as I happen to be simultaneously watching NatGeo’s Aftermath: Population Zero and writing this very piece when the subject of the effects of manmade noise on ocean life was raised by the narrator.
Now that all the tea leaves have aligned in favor of ocean noise pollution, I guess the only relevant thing I can do is provide some information and research I have encountered. According to the NRDC (Natural Resources Defense Council), scientists have proven the use of sonar to be dangerous to marine life and cite numerous cases involving uses of sonar that coincided with the strandings of multiple whale species across the globe. The NRDC states, “Many of these beached whales have suffered physical trauma, including bleeding around the brain, ears and other tissues. In addition, many have shown symptoms akin to a severe case of the bends.”
The information on the NRDC website was great, but I wanted to get a first hand glance at the reports, research, and conclusions. Hence, I peeked through three reports on the effects of noise on marine mammals produced by the National Research Council in 1994, 2000 and 2003. According to the reports for example, strandings of beaked whales were unmistakably connected to the use of mid-range tactical sonar, beluga whales demonstrated behavioral responses to icebreakers as far away as 50km, and gray whales and orcas abandoned critical habitats because of manmade noise. The reports also documented more subtle behavioral modifications to which long term injurious effects are not yet known:
-Fewer blows per surfacing
-Longer intervals between blows
-Ceasing or increasing vocalizations
-Shortening or lengthening duration of vocalizations
-Changing frequency or intensity of vocalizations
With over 90% of worldwide trade utilizing ocean transportation, the dominant sounds in our seas have shifted from marine life to shipping. We are now faced with what must be done to ensure the effects, or accumulation of effects that such a shift in ocean noise will ultimately have on the survival of marine mammals.
“This intentional and unintentional introduction of sound in the ocean associated with activities beneficial to humans must be balanced against known deleterious effects on marine mammals.” Ocean Noise and Marine Mammals (2003)