Several recent studies highlight the heightened risks of increased Arctic shipping, along with some opportunities to minimize the effects of shipping noise on specific Arctic species and populations.

With the retreat of sea ice, both the Northwest Passage (along Canada’s northern coast) and the Northern Sea Route (along Russia’s northern coast) are seeing increases in commercial and fishing vessel traffic. While the first cruise ship crossed the Northwest Passage in 2016, Russia’s Northern Sea Route is the current center of activity, with both container ships and LNG (natural gas) tankers making pioneering transits without icebreakers over the past two summers.  Total ship numbers are still modest, as it’s not yet cheaper than the longer route through the Suez canal, but these test runs are explicitly intended to chart the course for rapid increases in the coming years; Russia aims to ship 80 million tons of cargo by 2024, up from 10 million tons in 2017 and 2018, and China is moving rapidly to implement a “Polar Silk Road” initiative to encourage companies to build the infrastructure necessary to ramp up this shortcut to European markets.

Two recent studies address key questions about the biological impact of increased shipping on Arctic ecosystems.  The first, from researchers at the University of Washington and the University of Alaska at Fairbanks, examined the ranges of 80 localized subpopulations of seven key Arctic species, and found that just over half (42) of these would hear increased shipping noise.  Of these, some species are more vulnerable than others:

“Narwhals have all the traits that make them vulnerable to vessel disturbances — they stick to really specific areas, they’re pretty inflexible in where they spend the summer, they live in only about a quarter of the Arctic, and they’re smack dab in the middle of shipping routes,” said co-author Kristin Laidre, a polar scientist at UW Applied Physics Laboratory’s Polar Science Center. “They also rely on sound, and are notoriously skittish and sensitive to any kind of disturbance.”

In addition to narwhals, beluga and bowhead whales and some subpopulations of walrus are likely to be vulnerable to increased noise; ringed and bearded seals, as well as polar bears, will be less vulnerable, thanks to widespread populations and spending much of the summer on land rather than in the water.  In addition, the researchers stressed that the Bering Strait is a key chokepoint for both Arctic sea routes, as well as being a crucial migratory corridor.

“I think we can learn a lot from areas that have already been thinking about these kinds of conflicts between ships and marine mammal populations — for example the North Atlantic right whale, or fin and blue whales around California,” Laidre said. “We could aim to develop some mitigation strategies in the Arctic that help ships avoid key habitats, adjust their timing taking into account the migration of animals, make efforts to minimize sound disturbance, or in general help ships detect and deviate from animals.”

A second study took a different tack, looking at whether speed reductions (as implemented in some areas around busy ports) would reduce the noise impacts.  They used an increasingly common metric, “listening space,” the area or volume of water within which an animal can hear its brethren, its prey, or other biologically important sounds. The researchers modeled ship noise in several key chokepoints on the Northwest Passage, calculating the distance over which vessels sounds would impact the listening space for several species, and at how much the effect could be moderated if the ships were slowed in key areas.  And indeed, the effects were significant:

Under quiet conditions, beluga whales experienced a 50 percent listening space loss when they were 7 to 14 kilometers (4.3 to 8.7 miles) away from a ship traveling at 25 knots. When ships slowed to 15 knots, whales could get as close as 2 to 4 kilometers before they experienced the same loss of listening space.

In other words, when a ship was going faster, the area over which it cut a beluga’s listening space in half might be more than three times larger. This difference is important because there are many places where whales cannot distance themselves from ships in the Arctic (in the narrow Prince of Wales Strait, animals can maintain a maximum distance of just 7 to 10 kilometers).

As always, the results are not all as simple as that; the researchers found that for some species, the effects are less in certain weather conditions or for different kinds of ships (container vs. cruise), and that in some situations, the effects can actually cover a larger area when ambient noise is high (as it increasingly is with loss of ice cover). And, as always with vessel-slowing programs, planners must consider the tradeoffs between moderating the noise level and increasing the time during which ships are audible during slower passages.

With the inevitable increase in Arctic shipping, it will be crucial for both governmental and commercial players take steps to minimize the acoustic impacts in these remote waters, among the last areas in the seas where human noise intrusions have been relatively modest.

Last fall’s innovative 2-month voluntary slow-down of ships traveling to and from the Port of Vancouver was successful on one count—average overall shipping noise was reduced by 44%—but a stark absence of the normally abundant resident orcas stymied the equally important second line of inquiry: how would reducing the noise level, but spreading more moderate noise over longer time periods, affect orca behavior?

About 60 percent of the ships transiting Haro Strait complied with the voluntary speed restrictions; even this level of participation succeeded in reducing the overall level of ship noise by 2.5 decibels, very close to the 3dB target set by the International Whaling Commission a decade ago. Thanks to the logarithmic scale of decibel measurements, a 3dB reduction amounts to cutting the sound energy in half. This is great news, a real-world confirmation that the noise of global shipping can be reduced relatively easily—albeit by increasing transit time.

It’s this element that marine mammal experts remain uncertain about. Slower ships remain audible for longer during their passage, though at a lower volume; perhaps worse, the quiet periods between the passage of large ships became notably shorter and noisier, thanks to the lingering presence of ships in the mid-distance. What is more livable: a constant lower noise level or trading off louder periods for interims with relatively little noise? As researcher Scott Veirs notes. “I’m not sure which I would prefer, but we definitely don’t know which the whales prefer.”

An excellent in-depth article on the Seattle nonprofit news site Crosscut tells the tale of the researchers waiting on shore to monitor whale behavior. But rather than seeing whales on most days, there were no orcas at all during the first month of the slowdown, and only six appearances in the second month. A stark lack of salmon kept the orcas out of the area; salmon shortages are the primary factor driving the decline in the Southern Resident orca population. A recent modeling study by a diverse group of researchers suggested that increasing salmon numbers by 15% while also reducing shipping noise by half would allow the resident population to recover. (The decrease in salmon numbers is compounded by a boom in populations of seals and sea lions, who also eat salmon.)

The Crosscut piece zeroes in on the questions facing British Columbia, where new oil and gas ports and expansion of existing pipelines could add even more ships to the mix:

Piloting his 31-foot research boat Wishart back to Seattle from the San Juan Island study site, Rob Williams mused on his 20 years studying killer whales. “A whole lot of science has been done already,” he said. It may be time to start making some  difficult policy decisions about vessel noise, Williams said, and that means weighing safety issues and economic tradeoffs alongside concern for the whales. A number of factors, including the Canadian government’s approval of Kinder Morgan’s pipeline to export oil to Asia, could drive future increases in Port of Vancouver vessel traffic.

“What we have to do next is to have some really uncomfortable conversations. . .about how much of this acoustic space do we think it is fair to ask the whales to give up.” Williams said. “And how much are we willing to give up to have killer whales persist?”

“And those aren’t science questions,” he continued. “They are really tough value judgments.”

The burgeoning field of soundscape ecology (also dubbed ecoacoustics) is poised to take a remarkable leap forward during the just-beginning Australian summer  of 2018.  By mid-year, researchers plan to install 400 microphones in 100 locations spanning the continent’s seven diverse ecoregions.

At each location in this Australian Acoustic Observatory (A20), two acoustic recorders will be placed in relatively wet habitats for that biome (wetland, river, creek, drainage, depression) and two in relatively dry areas. Every six months or so, researchers will swap out the SD cards at each location and upload all the files to the project website, where everyone can engage with this extraordinary dataset.

David Watson, one of the Chief Investigators, noted in an introductory article:

One of the strengths of this project is our ability to use sound to picture time. We can prepare fascinating visualisations that contain months’ worth of data in a single image.

Some of the effects we’re measuring, such as the impact of cane toads and other invasive species, have very obvious acoustic signatures. They are dramatic to hear, but even more striking to see in a sonograph (essentially a graph of sound).

We’ve pioneered the use of false-colour spectrograms to visualise long duration recordings. These make clear the flattening effect of invasive species, or the long-term subtle shifts caused by climate change.

You absolutely want to check out those two links he provides! The first is to a short article containing an interactive 24-hr spectrogram which plays several minutes from each of three different times of day; the second is a thorough project description that was shared at conferences when they were in the pilot phase last year, and includes a deeper look at their innovative approach to spectrograms and the types of information they expect to glean in various habitats. It all promises to be a fascinating and exciting step forward for soundscape ecology.

Two troubling reports have surfaced regarding beluga whale populations in waters that have become increasingly industrialized and noisy in recent years.  In Quebec’s Saguenay River, the major river system draining into the St. Lawrence, recent years have seen a sharp uptick in dead beluga babies and pregnant mothers; in 2015, these sensitive individuals were half of all known mortalities.  Increased noise is the primary culprit; according to the CBC, “The researchers are working from the theory that beluga calves have soft calls, which may be drowned out by the noise from ships, ferries and boats in the Saguenay and St. Lawrence rivers.”

In Alaska’s Cook Inlet, beluga range has shrunk dramatically over the past couple of decades (see map below), and accelerated in recent years, as ongoing port construction and oil and gas development has introduced increasing levels of noise into these key waters.  It’s unclear whether the smaller range is simply a reflection of a reduced local population, meaning they don’t need to range so far to avoid competing with each other for food, or if they are responding to the increasing chronic noise.  See previous AEInews coverage of the Cook Inlet belugas here.  Recent NMFS research papers on the changes can be accessed at this link, and this in-depth article from a couple years back is a good overview of the current development and research activities.

Some of the most interesting new work in ocean noise is revealing the myriad ways that humanity’s sounds can have negative impacts on ocean life other than marine mammals.  Sure, everyone loves our warm-blooded kin, but there’s way more to the ocean ecosystem than dolphins, humpbacks, and seals.  AEInews has been covering this leading edge for years (see these posts on shellfish larvae, crabs, and squid).  Recently, at the triannual Effects of Noise on Aquatic Life conference, held this year in Dublin, a slew of new papers revealed further concerns.

This post from NRDC summarizes the highlights.  One of the most striking findings was that 6 hours of shipping noise can damage the DNA in the cells of mussels, perhaps due to a stress response; similarly, protein structures in the sensory cells of cuttlefish were damaged by low-frequency noise.  These would be some of the most profound impacts yet discovered; note, though, that the brief summary here does not specify the sound levels—some research on health effects use much higher exposures than are likely in the wild, as a way of identifying possible effects for further study at lower exposure levels.  Other new studies followed on previous ones that suggest many animals respond to noise as if it were a predator; these responses often suggest increased stress, and are waste of precious energy, or disrupt feeding.  Also of note is a one-off anecdotal observation (not yet studied systematically) of a hermit crab exiting its shell after exposure to low-freqency sound; it appeared to be examining its shell, perhaps trying to determine the source of the disruption, or checking for physical damage. While out of its shell, it would be vulnerable to predation.

All this new research is both exciting, as it reveals the vast and subtle role of sound in the natural world, and sobering in facing us with the widespread consequences of our heedless sonic intrusions into wild ecosystems.

I recently returned from the 2016 Ecoacoustics Congress, the 2nd meeting of the new International Society of Ecoacoustics, held this year at Michigan State University in Lansing. It was a very informative gathering of fascinating researchers from around the world; several traveled from Australia, a couple from Taiwan, many from Europe, and some from South America. I’ll add more here soon about this rapidly-advancing field, but for now, I wanted to quickly post a PDF version of my presentation:

Saving High-quality Acoustic Habitat: Identifying areas of relative natural quiet by Jim Cummings

In a second letter to the Obama administration, 28 top ocean noise and whale researchers have raised serious concerns about planned seismic surveys along the east coast of the U.S.  The scientists cite several recent studies that shed light ways that the long term health and reproductive rates of right whales have been affected by temporary stresses, and suggest that the planned seismic program could push this extremely endangered species over the edge.  With only 500 individuals remaining, the loss of each individual creates a significant impact on long term population viability.  According to the letter,

For more from the researchers involved, see this press release that includes several quotes, and for more on the maps, produced by Oceana, see this article from the Coastal Review and this page on Oceana’s website.

Over the past few years, researchers have developed an increasingly diverse set of platforms for listening in on the world beneath the ocean’s waves.  Now, in addition to recorders deployed in key areas for months at a time and temporary suction-cup acoustic tags on individual whales, a long-anticipated mobile option is moving into more widespread use.  Autonomous gliders offer an enticing combination of attributes: they can operate for weeks or months at a time, exploring a region rather than staying in one place; they can be outfitted with a range of sampling capabilities; and they are relatively inexpensive to build and deploy.  Subsea gliders can dive to 200 meters deep and resurface periodically to transmit data to data centers on shore; they’ve been used for physical sampling of oceanographic data (temperature, salinity, etc.) for many years, but it’s only more recently that acoustic sampling has become common.

The most exciting thing about putting recorders on gliders is that they can operate around the clock, monitoring for whales even in bad weather and at night, when ship-based researchers cannot.  Plus, the cost of operating research ships means that field studies are short and targeted to areas already known to be hot spots for whale activity, while gliders can be used to explore regions that we know less about. In particular, we know that whales tend to move around season-to-season in search of the best feeding opportunities; on the Scotian Shelf in the Canadian Atlantic, some areas that are protected feeding habitat have been largely abandoned in recent years due to lack of prey.  Gliders can help identify where the alternative feeding grounds may be, so they, too, can be protected.

This spring the Canadian WHaLE project (Whales, Habitat, and Listening Experiment) is expanding to the west coast. For three weeks, a six-foot glider will explore waters off Vancouver Island.

“Ocean gliders are a new technique for gaining insights into whale ecology on Canada’s West Coast,” says David Duffus, who leads the west coast project. “Many species of concern under Canada’s Species at Risk Act are termed ‘data deficient.’ We need more information on whale habitats and whale feeding ‘hot spots’ so we can put in protective measures, such as real time whale-alerts for shipping traffic.”

In addition to the longer-term goal of increasing our understanding of changing habitat use patterns, the gliders could also help reduce ship strikes. There is hope that in some especially busy shipping lanes, gliders may offer a new way to let ship captains know when whales are nearby; this is especially important for the critically-endangered North Atlantic right whale.

A new network of long-term acoustic monitoring stations is being deployed by NOAA-funded researchers in ocean waters from Massachusetts to the Arctic and Samoa. The Ocean Noise Reference Station (ONRS) Network represents the next step in data collection for NOAA, which has increased its focus on ocean noise in recent years.

Agencies, researchers, and NGOs are all concerned about the effects of chronic moderate noise on whales, seals, and fish (along with crustaceans and even eggs and larvae).  NOAA’s ocean noise mapping project is a big step forward, but it’s largely based on modeling of known ship and seismic survey activity.  Actual recordings made at sea by various researchers serve as “ground-truthing” for these models; early indications have been that the models are pretty good, usually within 5-10dB of actual recorded levels.

The ONRS network takes acoustic monitoring another step forward by deploying identical equipment in many regions, thus collecting “consistent and comparable multi-year acoustic data sets covering all major regions of the U.S.”  In addition to getting a better idea of regional differences (and consistencies), researchers will be investigating “how the ‘soundscapes’ at each of these sites changes, i.e. does it become noisier, are there more or less biological sounds, and is there a dramatic shift in the species present?”  All this will feed into NOAA’s ten-year effort to develop an Ocean Noise Strategy.

The most recent deployment took place this fall at the Cordell Bank National Marine Sanctuary off the coast near San Francisco (it’s not even on the maps on the NOAA site yet, though I added it above as NRS11).  The hydrophone deployment mission (right) received substantial funding from the International Fund for Animal Welfare (IFAW), along with the ongoing NOAA support for data collection and analysis.  Cordell Bank is one of the richest foraging grounds for marine mammals, thanks to an upwelling of cold water that attracts a wide range of species to feed.  At the same time, many of the thousands of ships traveling from Asia to ports in San Francisco Bay and further south along the California coast pass close enough that their “acoustic footprint” extends into the Sanctuary.  This can, at the very least, make it harder for whales or fish to hear each other as well as they’re used to, limiting the area over which they can communicate and causing them to raise their voices.  There are also indication that some species expend energy avoiding moderate noise, and that feeding and perhaps mating can be temporarily disrupted.  Most pernicious may be the possibility that living in elevated noise can increase physiological stress, triggering “a suite of negative effects,” according to one of the researchers.

Other research efforts are also adding to our understanding of the effects of shipping noise.  In Canada, Port Metro Vancouver recently deployed a hydrophone to examine the underwater noise from container ships headed into its facilities.  3000 such vessels traverse the waters each year, along with even more ferry transits and various recreational boats.  It’s part of the Port’s Enhancing Cetacean Habitat and Observation Program. One of its most interesting goals is to zero in on ships that may be unusually loud and in need of some maintenance:

The hope is to establish baseline information to track noise levels and to identify noise levels from specific ships. The results could lead to simple mitigation measures such as hull and propeller cleaning, shore-based financial incentives, and information for regulatory agencies and for naval architects to build quieter ships.

Here’s some more from the researchers on that project.

And in the Bering Sea, acoustic monitoring is providing important baseline data on marine mammal presence, which will play into any future oil and gas development, as well as the potential for global shipping to extend into Arctic regions as polar ice melts:

“This passive acoustic monitoring technique allows us to detect the presence of vocalizing marine mammals continuously — 24 hours per day — in all weather conditions, over periods of weeks to months, over distances of 20 to 30 kilometers, and is a proven sampling method in the waters offshore Alaska,” explained lead researcher Kathleen Stafford.

Meanwhile, eavesdropping went on during the summer and fall in the Gulf of Mexico, and plans are being made for a recording network all the way around Antarctica, in some of the world’s most remote and acoustically pristine waters.

We’re listening more closely and widely than we ever have—the next question will be, are we willing to actually do something with what we learn, and find ways to slow or roll back our relentless intrusion into the natural soundscapes of the oceans?

AEI lay summary of Rob Williams, Christine Erbe, Erin Ashe, Christopher Clark. Quiet(er) marine protected areas. Marine Pollution Bulletin (2015), http://dx.doi.org/10.1016/ j.marpolbul.2015.09.012  View or download paper online

Over the past decade or so, concern about ocean noise has expanded from its initial focus injuries and deaths caused by periodic loud events, such as sonar or seismic surveys.  Many researchers are now working to understand the ways that widespread, chronic shipping noise affects marine creatures’ behavior, foraging success, and stress levels.  Long-term deployment of hydrophones, sound models that extrapolate from shipping data, and slow-but-steady improvements in our knowledge of the hearing ranges and population densities of particular species have all combined to open exciting new avenues for research that can inform policy decisions in the years to come.

Using these new measurement and modeling techniques, researchers can quantify the “acoustic quality” of marine habitats.  This starts with charting the extent of shipping noise, while also considering the different auditory ranges of various species of interest.  Next, researchers map where animals tends to congregate in various seasons, to identify areas that are especially important to each species.

Of particular importance is identifying areas that have, so far, remained relatively free of shipping noise.  If at all possible, we’ll want to avoid extending the human noise footprint into these increasingly rare acoustic havens.  A research team that’s been active on Canada’s southwest coast over the past few years has been at the forefront of these techniques, and has just published a new paper that introduces the concept of “opportunity sites”—areas used by each species that are still relatively quiet, and so have high long-term conservation value.

“We tend to focus on problems in conservation biology. This was a fun study to work on, because we looked for opportunities to protect species by working with existing patterns in noise and animal distribution, and found that British Colombia offers many important habitat for whales that are still quiet,” said Dr. Rob Williams, lead author of the study. “If we think of quiet, wild oceans as a natural resource, we are lucky that Canada is blessed with globally rare pockets of acoustic wilderness. It makes sense to talk about protecting acoustic sanctuaries before we lose them.”

Below left: population density of harbor porpoise in coastal waters of British Columbia; below center: ship noise, weighted to harbor porpoise hearing; below right: opportunity sites to preserve high-quality acoustic habitat for harbor porpoises. Red indicates “highest”, blue “lowest” on all maps.

These new opportunity maps make it painfully obvious how little of each species’ habitat is free of excessive shipping noise. In the example above, harbor porpoises can only find high quality acoustic habitat in a couple of small areas.  Without some concerted effort to protect these areas, they will continue to shrink.

While recognizing that many areas of critical habitat are already too loud (in particular, the entire Seattle/Vancouver region), the authors acknowledge that reducing existing noise is difficult—limiting shipping, or reducing the noise made by boats, has social and economic costs that can be hard to accept.  By contrast, the areas they’ve identified merely need to be maintained in close to their current acoustic condition, which will be far easier to accomplish.  As the authors note:

Generally, large ship noise is far more audible for baleen whales (humpback, fin, etc.) than for smaller toothed whales (dolphins, orca), which vocalize and hear at higher frequencies. That’s not to say that the smaller whales don’t hear big ships; they often do, and in many cases, they respond at a lower sound level than larger whales, so even if the ships are “fainter” to their ears, their reactions may be similar.

While this paper steers clear of any sort of advocacy tone, and does no more than present the new “opportunity sites” analysis and mapping technique, the waters being studied are at the center of a contentious public policy debate.  The proposed Northern Gateway pipeline from the oil sands region of Alberta would dramatically increase tanker traffic to the existing deep-water port at Kitimat (yellow arrow, left).  Such an increase through Caamano Sound (red arrow, left) would threaten the humpback whale opportunity site (map, left) identified just south of the Sound.  Several years ago, co-author Rob Williams told reporters, “Caamano Sound may be one of the last chances we have on this coastline to protect an acoustically quiet sanctuary for whales. … We don’t exactly know why this area is so rich, but there are some long, narrow channels that serve as bottlenecks for food, making it easier for whales to feed.” A consortium of environmental organizations is currently challenging the Canadian government’s approval of the pipeline, claiming that the approval did not take into account the humpback recovery plan, identifying Hecate Strait (the larger area between the mainland and the large offshore island) as a critical humpback feeding ground.  The pipeline is being challenged on several fronts (including strong opposition from B.C. First Nations communities); considering acoustic habitat protection, limiting new ship traffic during the times of year when the current opportunity sites are being heavily used would seem to be the least we can do.

Bioacousticians and marine advocates have been closely following plans for the Northern Gateway pipeline in British Columbia, which would greatly increase ship traffic in some coastal waterways that are relatively quiet so far; see previous AEInews coverage.  But another pipeline project, farther along in the permitting process, could push the already stressed waters of southern BC and northern Washington to the acoustic breaking point.  The Trans Mountain Pipeline, built in 1953 and expanded several times since then, is gearing up to nearly triple its capacity and make adaptations that will allow heavy tar sands oil to be moved to the Pacific coast for shipment to Asia.

The expanded Trans Mountain Pipeline would have 75% of the capacity of the proposed Keystone KL pipeline to the Gulf of Mexico, so it has triggered active resistance on similar climate change grounds as Keystone.  At the same time, ocean advocates are stressing the cumulative impact of the additional 720 tanker transits that would occur in already-busy waters that include critical habitats for killer whales, sea lions, and other species.  At this point, most of the additional capacity is targeted for Burnaby, BC (increasing monthly tanker arrivals from 5 to 34), though the pipeline also serves terminals in northern Washington state. (Some of the current capacity is refined and used in North America, but virtually all of the increased capacity will be shipped overseas; thus the tanker traffic will increase 7-fold despite the smaller capacity increase.)

The Canadian Department of Fisheries and Oceans has just released a review of the Trans Mountain proposal, which is currently being considered by the National Energy Board (NEB), and finds it lacking, saying it contains “insufficient information” to adequately assess the threats posed both by underwater noise and ship strikes. “The assessment considers noise from a single project-related ship, without taking into account the additive and cumulative effects of existing noise,” Fisheries and Oceans Canada concludes.

Marine advocates second that concern.  Margot Venton, a staff lawyer with Ecojustice, stresses that “The critical habitat is basically as noisy as it can be. We need to make it quieter.” Misty MacDuffee, a fisheries ecologist with Raincoast Conservation Foundation, said anything that impedes the ability of whales to feed is a serious concern. “It’s just the growing din,” she said. “They are trying to [communicate and hunt] in an increasingly loud environment.” (Thanks to the Globe and Mail for their coverage and all these quotes.)

The NEB review is slated to be concluded by July; the federal government will then take six months to consider the NEB’s recommendation and make a final decision.  If approved, construction could begin in 2016 and be completed the following year.

UPDATE, 7/14/16: The NEB has recommended that the pipeline be approved, despite the likelihood that additional ship traffic will saturate the acoustic environment to the point that ship noise is present in some areas nearly 100% of the time (currently 85%).  Transmountain will need to meet 157 conditions, but they’re confident that will be achievable.  The final stage of the approval process is a final decision from the Canadian government, which is expected by the end of this year.

AEI lay summary of:
Daniel E. Holt, Carol E. Johnston. Traffic noise masks acoustic signals of freshwater stream fish. Biological Conservation 187 (2015) 27-33 (ScienceDirect link)
With each passing year, we learn more about the ways that animals use sound—and so also how human noise interferes with their lives.  A new paper looks at how traffic noise from bridges may impinge on the mating calls of freshwater fish; this is the first study to use some of the new metrics of “communication space” in these important and widespread habitats. The species studied was the blacktail shiner, a member of the largest family of fishes (including carps and minnows), with the study sites being small streams passing under bridges on I-85 in Alabama (image shows one of six sites).

Male shiners make two sounds during mating: loud “knocks” used to challenge other males who are intruding, and softer “growls” used to court females.  Streams are naturally loud environments, with noise from wind, rain, and turbulence; shiners take advantage of a relatively quiet “window” in the broadband noise, between 172 and 366Hz (like many other animals that vocalize in frequency ranges less cluttered by local sounds or other species).  While the traffic noise is not much louder than the natural stream sounds at frequencies above 700Hz, unfortunately for the shiners, in this key quiet window it is significantly louder than the stream noise—and also the seductive growls of male shiners.  The graph shows natural ambient noise (green), road noise (red), and growls (black dotted line).  The two peaks in the growl acoustic spectrum are particularly important; the lower peak in particular is dramatically drowned out by traffic noise.

The bottom line for the fish is that their knocks, which can be heard above the natural sounds of the creek out to about a half meter, are just slightly masked—only within three meters of the bridge are they lost in road noise (3m is the mean; maximum modeled range of effect is 22m).  So these calls of challenge and defense among males, which may also show females who’s the most fit, can serve their purpose unless the action is taking place right under a bridge.  The subtler sounds of the growls, however, are much more impacted.  These sounds, being quieter, are meant to be heard at very close range (generally just a few inches from the nest sites); yet the lower peak in the growl sound spectrum will be effectively inaudible in areas out to 640m (almost a half mile) from a bridge, and the second peak will be similarly masked out to 40m (both distances are means; maximum ranges are, respectively, 12km/7 miles and 1600m/1 mile). Adding insult to injury, peak spawning time is morning, before water temperatures rise, which may coincide with peak morning traffic.  Of course, only a small portion of most spawning streams is near heavily travelled interstates or secondary roads; those near more sporadically-travelled local roads are likely to be less affected.  Still, if the effect extends a half mile or more, large stretches of many streams could have some degradation of their natural and necessary acoustic habitat.

The authors’ conclusion neatly sums up what all this means going forward:

Several independent research projects that are listening to fish and whales in waters along the coast from New Jersey to Maine have joined together as the NorthEast Passive Acoustic sensing Network (NEPAN).  This map shows the location of the various research programs that will be taking place through 2017:

The NEPAN website offers a good overview of the aims of each of these projects.  Of particular interest is a real-time buoy deployed near a Coast Guard gunnery range off Rhode Island, which will help the Coast Guard to avoid initiating live-explosive exercises when any of the few remaining critically endangered North Atlantic right whales are in the area.  The array of long-term recorders along the edge of the continental shelf will also provide some key new information on seasonal presence of many whale species, as well as helping clarify how far offshore they tend to be during migration (again, especially crucial information for the right whales).

A letter from 75 leading bio-acoustics researchers urges President Obama to derail current plans to open much of the US eastern seaboard to oil and gas exploration and development.  Last year, the Department of Interior opened the door to new seismic surveys from Delaware to Georgia, which will clarify which areas of the continental shelf are most promising as drilling sites; these could begin as soon as this year or next.  So far, nine applications have been filed for surveys, all 50 miles or more offshore.  In January of this year, Interior announced plans to issue drilling leases beginning in 2017, with the initial five-year leasing period targeting roughly the same region (UPDATE, 3/15/16: Interior cancels lease planning); in conjunction with opening this area, development was banned in some Alaskan waters (small areas off the north slope and a larger area in SW Alaska).

 All this has spurred much public outcry, and in March an impressive array of ocean scientists from dozens of universities and research organizations around the world took the unprecedented step of sending a letter to President Obama expressing deep concern about the acoustic impacts of these plans. “The magnitude of the proposed seismic activity is likely to have significant, long-lasting and widespread impacts on the reproduction and survival of fish and marine mammal populations in the region, including the critically endangered North Atlantic right whale, of which only 500 remain,” say these researchers (see the full letter).

New dynamic maps from NOAA’s new Cetacean & Sound Mapping project indicate that these right whales use the southeast coast intensively in January and February, and are present along much of the coast in March and April moving north, and November and December heading south.  Only during the months of June-October are these whales mostly in northern waters away from the region currently being targeted.  Of course, other marine species are present year-round.

The Department of Interior suggests that since all activity will be more than 50 miles offshore, it should not interfere with commercial or recreational fishing, or near-shore areas of critical habitat; however, airgun sounds are often audible at much greater distances than that.  Energy companies also stress that heavy seismic survey activity in the Gulf of Mexico has co-existed for decades with both commercial and recreational fishing activity.

While initial push-back has largely been focused on the seismic surveys, which use pulses of loud sound to image deep below the seafloor (here’s a good explainer), the longer-term acoustic footprint of oil development is likely to also be significant. Ocean Conservation Research has been focusing on this for several years, tracking the new generation of seafloor processing facilities that are making deep-water development possible:

Much of the technology that makes deepwater drilling possible hinges on creating pre-refineries on the sea floor. These include seafloor separators, reinjection pumps, multi-phase pumps and other equipment all operating under extreme pressures and often very high (and noisy) differential pressures. Additionally these deepwater operations are typically performed from dynamically stabilized drill ships and “semi-submersible” platforms that are always churning away.

PacificWild, a British Columbian environmental organization, has deployed a network of 6 hydrophones in waters along the northern coast of that province.  This region of offshore islands and dramatic forested fjords is relatively wild, and quiet, especially as compared to the shipping-intensive region in southern BC around Vancouver Island and nearby Puget Sound in Washington State. But development proposals (including tar sands and other oil and gas ports) may mean up to 3000 supertankers per year will pass through these northern waters, bringing an expansion of the acoustic smog that already blankets most of the world’s oceans.

Ian McAllister of Pacific Wild stresses that “Most of the species that are acoustically sensitive rely on a quiet ocean in order to communicate, in order to forage, in order to survive here,” and notes that the hydrophone array will gather crucial baseline acoustic data that can help inform management decisions to be made in the next few years.

Live streams of the hydrophones are available, though at most times, there’s not all that much going on; a collection of highlights, as well as streams, is available on this page. To learn more about the project, see PacificWild’s website, or take a look at this brief video (see it here if it doesn’t load for you).

AEI lay summary of four recent papers:
Simpson SD, Purser J, Radford AN (2014). Anthropogenic noise compromises antipredator behavior in European eels. Global Change Biology (2014), doi: 10.1111/gcb.12685
Voellmy IK, Purser J, Simpson SD, Radford AN (2014). Increased Noise Levels Have Different Impacts on the Anti-Predator Behaviour of Two Sympatric Fish Species. PLoS ONE 9(7): e102946. doi:10.1371/journal.pone.0102946
Nedelec SL, Radford AN, Simpson SD, Nedelec B, Lecchini D, Mills SC (2014). Anthropogenic noise playback impairs embryonic development and increases mortality in a marine invertebrate. Sci. Rep. 4, 5891; DOI:10.1038/srep05891 (2014).
Erica Staaterman, Claire B. Paris, Andrew S. Krough (2014). First evidence of fish larvae producing sounds. Biol. Lett. 2014 10, 20140643.

It used to be that most concern about human noise and ocean life was centered on whales and the two loudest sound sources: sonar and seismic surveys.  But in recent years, we’ve seen a growing wave of studies looking at how chronic, moderate ship noise can interfere with normal behavior and development of other creatures, including squid, fish, crustaceans, and other “lower” species.  Four recent studies add to the list of known or suspected ways that shipping and recreational boat noise may be wreaking previously unsuspected havoc throughout the oceanic web of life.

The most dramatic results came in a study of eels’ responses to predators (above). When exposed to ship noise, only half as many eels responded to an ambush attack from a predator (just 38% reacted, down from 80%); and, those that did react did so 25% slower than normal. Likewise, researchers tested eels’ ability to detect a “pursuit” predator that follows the eels before attacking; in this case, the eels in ship noise were caught twice as quickly.  Looking deeper, the researchers examined how noise affects metabolic rates, stress, and breathing rates, and an interesting feature of eel life, the preference for using one side of their body when interacting with other eels and when hunting.  The researchers explain:

“In the same way we write using our right or left hands, fish have a preferred side to approach a predator or to stay next to shoal mates with. We watched each eel as it explored a maze in ambient conditions to classify its right or left bias, then we exposed half to ship noise and half to more ambient noise. Their preferences went away when they were exposed,” says Dr Steve Simpson of the University of Exeter, lead researcher on the study. The team suspect this means ship noise affects eels’ cognitive processes, which could mean other processes, like learning, may also be affected. Alongside raised metabolic and ventilation rates, the scientists note the stress being caused by the shipping noise is similar to the levels fish exhibit in ocean acidification studies.

“We know shipping isn’t going to stop, but we can do things like move a shipping lane so it doesn’t interact with the migrations paths of animals,” Simpson suggests. “It’s a pollutant we have more control over than something like atmospheric carbon dioxide. These animals are having to deal with all the stressors globally, so if we can alleviate just one it might give the animals more resilience to other stressors like ocean acidification, which will come later.”

A study of two species of small fish highlights species differences and the ways that noise can alter behavior in unexpected ways.  Here, one species of fish exposed to ship noise actually responded more quickly to the presence of a predator,

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For several years, AEI has been excited about the ever-expanding networks of ocean observatories coming online around the world.  A recent article on LiveScience detailed some of the benefits of the arrays of research stations deployed offshore by Ocean Network Canada, which collect all manner of data: physical, chemical, biological, geological, and acoustic.  Their two networks, the offshore NEPTUNE (left below) and the near-shore VENUS (right below), consist of permanent installations on the floor (“nodes,” shown as orange squares below) as well as mobile moored sensors that may take measurements higher in the water column (yellow dots). A similar US network, dubbed Regional Scale Nodes, is being planned off the coast of Washington and Oregon.

While the observatories are enabling in-depth study of complex process in ways not previously possible (click that link for a glimpse of the amazing topics being explored…yes, do it!), the audio feeds coming from some of the nodes hold special excitement for many researchers. “If you want to study what’s going on in the ocean, the best tool by far is sound,” said Tom Dakin, an acoustic specialist at ONC’s sensors technology development office.”There are all kinds of sounds being made in the ocean, and they all have a telltale signature. . . . If you start putting in a bunch of external man-made noise, [whales] are going to have a hard time communicating,” Dakin said. It’s like trying to have a conversation with somebody at a rock concert — you have to shout, you can’t hold a conversation for very long and you wouldn’t be able to detect different inflections that you would normally be able to hear.  He has been diving when a big ship has gone by, and “it feels like somebody’s whacking you in the chest with a two-by-four,” he said.

But while scientists are keen to hear what the new undersea recordings have to tell us, the US and Canadian Navies are far less enthusiastic.  They’re concerned that the audio feeds, which are freely available to scientists and the public as downloads and via live online feeds, will reveal sensitive information about submarine and ship movements, navy training activities, and even the sound signatures of individual vessels. The two navies have arranged with researchers to have an audio bypass switch that allows them to divert the audio streams into a secured military computer—sitting in a locked cage at the research facility where the data comes ashore—at times when their ships are nearby (and also at some random other times, so that their diversions don’t give away any secrets on their own!).  This article from The Atlantic dug into the way this system works, along with a quick look at naval concerns about sound from as far back as 1918.  The data diversions from Ocean Networks Canada’s system (often triggered by the US Navy) occur several times a month and last from hours to days. As noted by The Atlantic:

While the Canadian military has yet to return a request for comment, the U.S. Navy reminds me that naval ship movements are classified information, and the fact that those movements might potentially be broadcast on the internet is obviously of concern. “The value of having a cabled system is that it releases data live to the internet,” says U.S. Navy oceanographer Wayne Estabrooks. “But there are some times where we want to protect information, so we have to do diversions.”

…

“There’s a long tradition of the ocean being the exclusive domain of the militaries and the fishing community, and we’re more or less interlopers in this world,” says [Kim] Juniper, the microbiologist who showed me the photo of the computer in the cage. “The world is changing. . . It’s going to come to a point in the future where this is no longer going to be feasible for the navies to put resources into sorting all this data,” he later says. The hydrophones alone generate 200 gigabytes of raw data each day, and there are other, similar networks of Internet-connected sensors that already exist, or are soon to come online.

Dakin notes, though, that only 4% of the data is lost, and is returned to the science pipeline, often immediately and nearly always within a week.  The military filters out their ship noise, but leaves the rest of the data intact (at least, whatever data is not also in the frequency range of the navy ships or other sensitive sonic activities). “At end of the day, we hardly miss any data at all,” he says.  You can listen to live streams of ONC acoustic data here, and, since that’s rarely very exciting, to a collection of highlights of images and sounds here.

We’ve all heard that humpback whale songs have complex, repeating structures, and that the themes evolve over course of months and years. Yet listening to the gruts, guffaws, and groans of humpback recordings, it’s hard for most of us to really hear the large-scale structure that ties together these deeply alien sounds. In an article recently published on Medium David Rothenberg and Mike Deal have built on work done back in the 1970s by Scott McVay, and created a visual representation for humpback songs that makes it all suddenly and delightfully clear.

For starters, Deal created glyphs to represent particular “song units.” Each of these distinctive utterances is shown in a different color; the shapes mimic the shape of the sonogram of the sound. Following on McVay’s work with Roger and Katie Payne, Deal and Rothernberg show how these units are combined to create “phrases” lasting 20-40 seconds; several phrases create a “theme,” and a sequence of themes lasting 5-30 minutes is the “song.” Deal and Rothenberg take McVay’s work one step further by overlaying the units on an expanded musical staff to represent the frequqency of each phrase (each utterance of the whales includes a broad range of tones, like a chord with many audible overtones, so the glyphs stretch over a substantial span of the musical staff).

Finally, they present full songs in this new notational language:

As Rothenberg notes, “The pattern in the phrases starts to seem like an alien language. But even eerier is how much more human-like the order appears than most known animal vocal behaviors.” Go read the full article; it includes several videos of note, including one that animates the above notation while the 8-minute song is played, and one that explores the compelling similarities between humpback song and mockingbird songs. Also featured are many of the original notations done by McVay, which inspired this new take on it, and exceprts from a recent lecture by Katie Payne (see it here) that dives deep into the questions of cultural change and linguistics that are raised by the extraordinary nature of the these songs.

Earlier this month, Leila Hatch, one of NOAA’s leading experts on ocean acoustics and a long-time researcher in and around Stellwagen Bank National Marine Sanctuary, presented an hour-long talk on ocean noise.  It’s been archived on the Open Channels website, and is available for streaming and download on Vimeo.  

It’s by far the best introduction I’ve seen to this wide-ranging topic, including some basic information on ocean noise, along with a good summary of ongoing work at NOAA to map ocean noise and to learn more about how shipping noise, in particular, can impinge on whales’ communication space. Highly recommended!!

Listening to our Sanctuaries: Understanding and Reducing the Impacts of Underwater Noise in Marine Protected Areas from OpenChannels on Vimeo.

Two new research projects are taking important next steps in understanding the importance of sound, and clear listening, to whales.  In recent years, ocean bioacousticians have introduced the concept of “communication space” or “effective listening area” to scientific parlance. This began as a conceptual framework for thinking about how human sounds (especially shipping noise) may reduce the area across which whales can hear and be heard; researchers are now digging into more of the details of how this may actually impact animals in their daily lives.  After several recent studies that focused on whales hearing each other (and so framing their results in terms of “communication space”), two new studies are gathering initial data that may inform considerations of the ways whales listen for the presence of prey.  While whales can, and do, change some of their communication signals or patterns in order to be better heard by other whales in noisy conditions, there’s no such compensation that can help a whale hear their prey through a wash of noise.

Both of the new studies are taking advantage of acoustic tags to allow scientists to listen in on whales as they are foraging.  These tags are about the size of a large cell phone, and are attached to the animals with suction cups; they remain attached for up to 16 hours, then float to the surface for retrieval.  While attached, they record all sounds the whales hear and make, as well as logging swimming speed and dive orientation.

One study is further along, having just published its first results, which confirm that orcas can hunt in near-total darkness, apparently relying only on zeroing in on their prey (in this case, seals) by listening for their mating calls.  These orcas do not use echolocation while hunting (other orcas, hunting salmon, do echolocate); they hunt in stealth mode, then dispatch their victims with a swat of their tail flukes.  This initial evidence is not totally conclusive; followup studies will confirm that orcas do, indeed, seek out seal sounds.  And, this sort of study is but the first step toward quantifying the extent to which ocean noise may limit the range over which orcas can hear seals while hunting.

The second study will begin next year, and will be putting the acoustic tags on large whales, to see whether they’re using acoustic cues to help locate aggregations of fish.  According to Dr. Rochelle Constantine:

“Acoustics within the marine space are really important for many organisms, yet we don’t know a lot about how it drives organisms’ interaction with their environment. We’re interested in looking at how the larger animals use the acoustic environment, particularly for food, and testing the hypothesis that food patches have specific sound signatures.”

She said the sound of “bait balls” of prey, such as schools of fish, could be greatly heightened when a feeding frenzy involving larger fish and seabirds broke out.  Dr Constantine said whales had been observed swimming rapidly from over a kilometre away toward prey aggregations, “so we’re very interested to find out if there are specific acoustic cues they home in on”.

This study plans to play recorded sounds of fish aggregations and other prey sounds while the tags on the whales.  (I suppose if they happen to get lucky and have an actual feeding event occur while tags are attached, that will be a bonus, but the playback will serve as a reliable testing condition.)  This team is also interested in using acoustic tags on large fish and sharks, to explore the ways they may rely on listening, as well.

AEI lay summary of:
R. Williams, C.W. Clark, D. Ponirakis, and E. Ashe.  Acoustic quality of critical habitats for three threatened whale populations.  Animal Conservation (2013).

Innovative research along the coast of British Columbia has quantified the degree to which shipping noise is reducing the distance at which whale vocalizations can be heard.  This is one of the first studies to use recordings of actual ocean noise levels to examine how the “communication space” of whales is affected by shipping noise in an area where whale conservation is a priority.  Among its troubling findings is that endangered orcas are facing the highest levels of noise in areas that are legally designated as critical habitat, with communication space reduced to 25% or less even in average noise conditions; over the entire study region, the area over which orcas can hear each other can be reduced by 62% during average noisy conditions, and 97% during the noisiest times.  Humpback whales face nearly as large reductions in some key areas (though not formally designated critical habitat; and, notably, are showing signs of a tenuous recovery in some of the areas studied), while fin whales, who have louder calls than the other species, are only mildly affected by shipping noise.

(noise levels and communication space in median noise conditions)

Communication space (alternatively termed “effective listening area”) is a relatively recent introduction into scientific parlance; it’s a measure of the area within which a particular species can hear and be heard by others of its kind; both marine and terrestrial bioacousticians have begun using this framework to better understand the ways animals may be affected by increased background noise introduced by human activities, including shipping, roads, and airplane overflights.  Previously, small increases in background noise were commonly considered to cause only negligible impacts, since there is rarely a clear or consistent behavioral reaction.  However, many animals rely on hearing things at the edges of audibility (calls of their kin, the approach of predators, the presence of prey), and a significant reduction in an animal’s communication space can cause a need to use more energy hunting, or to be in a heightened state of alertness (and stress) to avoid predation.

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Southern right whales have begun giving birth in the waters around New Zealand.  Beginning in the 1920’s, none frequented waters around the New Zealand mainland, after an intensive decade of hunting in the 1800’s decimated populations.  In the 1990’s,  a few scattered sightings began, and in recent years, females and calves are started utilizing sheltered bays. According to Emma Carroll of Auckland University, the whales appear to have lost the knowledge that New Zealand was a valuable winter and calving habitat, but the early exploratory trips by individual whales seems to have led to it being “rediscovered.”

Ironically, considering the growing concern over the impacts of human noise on whales worldwide, early settlers in Wellington complained that whales in the harbor there kept them awake at night!  How the times have changed….

Researchers at Woods Hole Oceanographic Institution (WHOI) have completed a proof of concept study that appears to be able to identify individual whale calls in the data collected by seismic surveys.  In the initial data, the researchers were able to cull fin whale calls from the recordings made as airguns blasted their pulses of sound into the ocean floor.  Blue whales are also likely candidates for being heard on the recordings, since their calls also overlap with the frequencies of interest to seismic mapping efforts.

“We have a huge amount of data that can say, ‘Did they change their behavior? Did they stop feeding? Did they stop talking? Did they talk louder?’, and that’s what we want to know,” said WHOI seismologist Dan Lizarralde.

Lizarralde and collaborators are currently seeking funding to develop a computer algorithm that can help with the daunting task of extracting the whale calls from massive amounts of seismic survey data.

For the full story, including spectrograms and comments from other researchers, see this story on LiveScience.com

You may have seen some press coverage recently of the latest iteration of Cornell’s Macauley Library of Natural Sounds online.  Today, Wired put together a fun little game in a slide show on their site, in which you can listen to clips of odd animals sounds, and try to guess whose voice you’re hearing.  The accompanying article is a good introduction to the new Macauley archive, too.  After reading the article, you can start playing the game by clicking “next” on the upper right corner of the animal picture grid on that page…

In the wake of NOAA’s large-scale ocean noise mapping project, two much more detailed studies from the Pacific Northwest have highlighted the likelihood that current shipping noise is already pushing the limits of what biologists think many ocean creatures can cope with.

The first study recorded the sound from several types of boats and ships traversing Admiralty Inlet, between Whidbey Island and Port Townsend, WA, and used these recordings, correlated with ship traffic records, to model sound levels throughout the area.  The Seattle Times summarizes this work, which found that at least one large vessel (container ship, ferry, or large tug) was in the area at least 90% of the time, and that the average noise level was about 120 decibels, which is the threshold above which federal agencies begin being concerned about behavioral impacts on some ocean species.  

“Continuous noise at that level is considered harassment of marine mammals,” said University of Washington’s Christopher Bassett, one of the authors of the paper. “About 50 percent of the time, we even exceed that threshold.”

“It is concerning that the noise levels are so high,” said Marla Holt, a research biologist at Seattle’s Northwest Fisheries Science Center. “When you see how often this happens and how chronic the noise exposure is, that’s when you start to say, ‘Wow.'”

Interlude: Brief OrcaLab recording of threatened Northern Resident killer whales in Caamano Sound, BC, chatting with each other and then being drowned out by a cruise ship:
 

To the north, another study mapped shipping noise in the Salish Sea (south and east of Vancouver Island), and on up the British Columbia coast to the port of Prince Rupert.  This work, funded by World Wildlife Fund-Canada, introduces a comprehensive approach to modeling sound transmission from ships, incorporating differences between vessel types, transmission loss in a variety of bathymetric and seabed conditions, and temperature-driven variations in sound speed during different seasons. (Download a PDF presentation summarizing the full WWF-Canada report here; a shorter version appeared in JASA in November). Here, too, large areas are subject to excessive shipping noise; the maps below show total sound levels, and the areas where the annual average of two specific low frequencies are above the 100dB threshold that the European Union considers the target for biologically sensitive areas:

But now, check out that lighter colored patch about halfway between BC’s two big offshore islands.  

That’s an inland waterway that heads up to Kitimat, the proposed site of a major new port, the Northern Gateway, which would serve as the primary port for shipping tar sands oil to Asia.  An annual total 220 super-tankers would head though that currently mostly-yellow zone, all the way up that long, narrow channel that points to the upper right hand corner of this close-up (and leave again—so more than one passage a day on average).  As you might imagine, there is widespread concern about the risks of accidents and spills in these often treacherous passages, but the increase in shipping noise is also being raised as a question.

A second study by the same research team, led by Christine Erbe, took a close look at current and likely increases in shipping noise, should Northern Gateway go forward, and what they found is not reassuring.  Noise levels will increase by up to 6dB in the approach lanes in Caamano Sound, and by 10-12dB in the narrow fjord into Kitimat (see map on right).  In the western channel (the wider approach), where sound would likely increase 3-6dB (representing a doubling to quadrupling of sound energy), Humpbacks would hear tankers and their accompanying two tugboats for 43% of daylight hours, and orcas (due to thier higher-frequency hearing, less intruded upon by low-frequency ship noise) would hear the tankers 25% of the time.  Fewer whales venture all the way up the fjords, but some would likely be present in the bend in the route, where noise levels would increase by 10dB, representing a 10-fold increase in sound energy.

“There is a worry they will go away and not come back to these fiords,” says Erbe. “This is critical habitat, important to them. Are they going to be able to feed elsewhere? We can only answer that with long-term monitoring.”

These studies, one of which utilized four seasons of recordings, and the other presenting a comprehensive and verifiable sound modeling approach, both offer exciting steps forward in the study of coastal and oceanic acoustic habitats.  Let’s hope that coming years produce many more studies from other regions around the world that continue to develop these innovative techniques.

Detailed Northern Gateway study: Erbe, C., Duncan, A., and Koessler, M. 2012. Modelling noise exposure statistics from current and projected shipping activity in northern British Columbia. Report submitted to WWF Canada by Curtin University, Australia.

BC sound modeling study: Erbe, C., MacGillivray, A., and Williams, R. 2012. Mapping Ocean Noise: Modelling Cumulative Acoustic Energy from Shipping in British Columbia to Inform Marine Spatial Planning. Report submitted to WWF Canada by Curtin University, Australia.
Shorter version:   Erbe, C., MacGillivray, A., and Williams, R. 2012. Mapping cumulative noise from shipping to inform marine spatial planning.  J. Acoust. Soc. Am. 132 (5), November 2012. 423-428.

Puget Sound study: Bassett, C., Polagye, B., Holt, M., Thomson, J. 2012. A vessel noise budget for Admiralty Inlet, Puget Sound, Washington (USA). J.Acoust.Soc.Am. 132(6), December 2012

Related:
Kathy Heise and Hussein Alidina.  Ocean Noise in Canada’s Pacific Workshop, January 31-February 1, 2012.  Summary Report.  WWF-Canada.  54pp.  Read or download PDF

WWF-Canada Submission to Enbridge Northern Gateway Joint Review Panel, 9/19/12. (mostly terrestrial impacts; some ocean noise sections) Read or download PDF