Lay summary of:
Noise pollution is pervasive in U.S. protected areas. Rachel T. Buxton, Megan F. McKenna, Daniel Mennitt, Kurt Fristrup, Kevin Crooks, Lisa Angeloni and George Wittemyer (May 4, 2017). Science 356 (6337), 531-533. [doi: 10.1126/science.aah4783] Online access (subscription)

Ongoing data analysis by researchers from the National Park Service and Colorado State University is revealing an increasingly detailed picture of the sprawling impact of human noise in protected areas around the United States. The most recent paper from this groundbreaking team digs into the sound models to offer a better sense of how extensive the issue is, and highlights the promise of focusing conservation efforts on preserving areas where the human noise footprint remains small.

The researchers zero in on two key thresholds of noise: 3dB above the natural ambient sound, which marks a doubling of noise levels (causing a 50% reduction in the area over which sounds can be heard), and 10dB of excess noise, which is a 10-fold increase, leading to a 90% reduction in listening area. As the authors note, these are “levels known to interfere with human visitor experience and disrupt wildlife behavior, fitness, and community composition.”

The new maps include all protected areas in the US: federal, state, and local. Not surprisingly, the “natural” areas near cities tend to be very loud (yellow on the maps below, up to 30dB of additional human noise). Read the rest of this entry »

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.

Lay summary of
Rosanna CN Agnew, Valerie J Smith, Robert C Fowkes.  Wind Turbines Cause Chronic Stress in Badgers (Meles meles) in Great Britain.  Journal of Wildlife Diseases, 52(3), 2016. DOI: 10.7589/2015-09-231.  Download PDF

A new study out of Britain provides one of the clearest looks at whether wind farms create chronic stress in wildlife populations.  The results are striking—badgers living near turbines had stress levels 265% higher than the control groups—though not yet conclusive.

The researchers used what appears to be a very solid study design, testing cortisol levels in badger hair among 25 badger “setts” (dens, occupied by one or more badger families) separated into two groups: 9 “affected” setts were within 1km of wind farms, and 16 control setts were more than 10km from any wind farm.  They made an effort to assure that control setts were comparable in their habitat types, distance from roads, and geographic spread across Britain.

The overall results are fairly clear-cut.  Here’s a graph of the two groups; the boxes show the 3 quartiles of results in each group (the bottom of the box being the level that 75% of the animals were above; the line across the box showing the level where half the animals were above, half below; and the top of the box the level that 25% of the animals were above), with the bars outside the box showing the remaining scatter of individuals.  The mean among controls was .87, and among the affected group the mean was 3.16

A closer look at the results suggests that, as usual in field studies, there is a lot more going on than the means and medians suggest.  Here we see a plot of the 9 affected setts, with distance to nearest turbine on the bottom axis.  Interestingly, there is a wide scatter of results, with some setts (2 of the 9) showing levels very similar to the controls, about half (4 of the 9) having somewhat elevated levels, and only 3 setts being highly elevated, above the highest of the control setts.  Our first image shows this skew, with the upper quartile of the affected box stretching far above the middle line (and thus pulling up the mean to a significant degree).

This skewing does not invalidate the results; such scatter is very typical of most impact studies.  But it does remind us that there is rarely a simple, universal cause-and-effect.  The authors address many factors that could have contributed to anomalous results, and consider most of them to be quite unlikely; as they summarize, “Although certain intrinsic factors, such as sex, age, and disease status, have been thought to influence cortisol levels, it is very unlikely that the 264% cortisol increase experienced by affected badgers is a result of these factors alone.” Still, these and the other possible confounding factors will deserve closer scrutiny in followup studies.

The authors presume that vibration and noise, and likely infrasound, are the primary stressors, but did not do sound measurements as part of the study.  There was no mention of whether badgers are stressed by tall structures, as some small mammals are (due to predation by hawks).  While it seems likely that badgers are too large to be at risk from above, some confirmation of this would have been helpful to add, if true.

The researchers suggest that their results could have implications for controversies about humans who have reported negative reactions to wind farms, noting that badger hearing range is similar to humans.  A final finding was that the badgers did not appear to acclimate to the wind farms: setts near new wind farms had only slightly higher stress levels than those near long-established ones, where the mean remained well above that of the controls.

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

Somewhere out in the vast expanse of the Snake River plain this summer, the sounds of a natural gas compressor floats across the sage-strewn landscape.  Look around though, and you won’t see any wellpads or boxy compressor stations.  If your eyes are sharp, you may spy the source of the intrusive sound: a large solar-powered speaker.

It’s part of phase two of a study looking into the effects of human noises on wildlife.  Phase one was the “Phantom Road,” a half-mile string of speakers set up in an Idaho forest, which found that traffic noise caused notable changes in the makeup of the nearby bird population.  About half of the species in the area showed some avoidance of the sounds, with two species nearly absent when the speakers were on (one species preferred the noisy periods).  This study was summarized in AEI’s 2014 poster that summarized research on “The Effects of Chronic Moderate Noise on Animal Behavior and Distribution.”

By using speakers, rather than studying actual roads or oil development sites, researchers are able to separate out the effect of noise from the effects of the physical disruptions of the habitat (the loss of plant cover at the site itself, and access roads to the facilities).

The oil field study, which includes a six sites with speakers and six control sites with no added noise, is looking at effects of the noise on birds, bats, and insects.  And, they’ve brought birders out to their sites to see how oil development may affect their ability to hear birds and enjoy the landscape.  Some of the birders were surprised at how much even distant compressor noise interfered.  “The whole thing has been ear-opening, shall we say,” said Jim Lyons of Boise. “To be part of this is very stimulating, very interesting. I am going to think about it from now on.”

Shell Oil is gearing up to do the first new exploratory drilling in the Chukchi Sea off northwestern Alaska.  The project has been in the pipeline for years, and has faced numerous legal challenges (mostly regarding the danger of a spill and climate imperatives) and logistical snafus (the most extreme being a drill ship that ran aground).  Just last month, a consortium of environmental groups filed a suit challenging the most recent permits; there has yet to be a ruling.  The expansion of oil and gas development from Alaska’s north slope to offshore waters will create a marked increase in human noise in an ocean region that is currently relatively free of our intrusions.  Exploration leases have been sold in both the Chukchi Sea (left below) and Beaufort Sea (right below).

Earlier this year, the Obama administration officially put some areas in these waters off limits, but a close inspection of the maps presented then reveal that virtually none of these areas were planned for development when the above map was created in 2008; the exclusion zones appear to match the near-shore areas excluded above (one exception: a small portion of the Chukchi zone is now off-limits).

Noise concerns extend far beyond the drilling itself, or even the seismic surveys that take place prior to drilling and during the life of the project.  The drill rigs come along with a support fleet of 30 other boats and several aircraft, promising a steady din in the area.  “In the Arctic, I can’t emphasize how novel an activity this is,” says NRDC attorney Giulia Good Stefani. “It really is a whole new level of disturbance for an area already experiencing rapid change and stress.” Concerns extend from whales to walruses, seals, and polar bears.

A wide array of ongoing research is underway, aiming to characterize the current soundscape in arctic waters. Read the rest of this entry »

A new Federal Aviation Administration (FAA) effort to modernize air traffic flow around major cities is ignoring the chance to do slight re-routing that would minimize air traffic over dwindling areas of natural quiet.  The FAA is in the midst of a multi-year process to update the traffic patterns in and out of airports in 17 metropolitan areas.  Each “metroplex” is served by multiple airports, and the FAA’s goal is to increase efficiency and on-time performance, using a number of strategies, including more precise coordination of flights into shared flight paths.  This includes some effort to consolidate flight corridors, which has the good news/bad news effect of reducing air traffic noise over many areas, while increasing it in some of the new corridors.  Unfortunately, some of the new concentrations of activity are over areas that were previously sanctuaries of natural quiet.

The National Park Service’s Natural Sounds and Night Skies Program got involved early in this process, in the hopes that the new traffic schemes could reduce air traffic over relatively quiet park and wilderness lands.  Over the past twenty years, the NPS has pioneered efforts to highlight and protect natural soundscapes; their monitoring and management techniques are gradually being adopted by public lands managers in other state and federal agencies.  While deep wilderness settings are often the focus of these efforts (e.g. Grand Canyon, Yellowstone), many NPS holdings closer to urban areas provide easily accessible experiences of natural quiet.

A recent in-depth article in the East Bay Express looks at the way this has unfolded in the FAA’s planning of the Northern California Metroplex around the San Francisco bay area.  The FAA has largely spurned the input from NPS, which hoped to protect or improve natural quiet opportunities in the Point Reyes National Seashore and in Yosemite National Park.  Despite formal NPS requests, Read the rest of this entry »

In July 2011, 70 pilot whales were spotted in the shallow Kyle of Durness on the north coast of Scotland; as the tide went out, at least 39 were stranded.  Quick efforts by locals and live-stranding groups managed to refloat 20 animals, but 19 perished.  This month, a report commissioned by the UK’s governing agency, DEFRA, concluded that a series of bomb-disposal explosions were the most likely cause of the stranding.  It’s a good reminder that much of the potential impact on wildlife from Navy exercises is from traditional ordinance, rather than sonar.

While pilot whales are relatively common around Scotland, and there have been numerous strandings through the years, it’s unusual that they would venture into such a shallow, tidal bay.  It seems likely that the pod was in the area relatively near shore (either following food, or transiting between feeding locations) when several bombs were exploded on the day before the stranding (yellow pointer on image).  Navigational error (perhaps caused by hearing impairment) left them in the mouth of the bay (red pointer), 3-5 miles away, rather than offshore; the strandings had just begun when the final bomb was exploded the next day, which likely drove more animals into the shallows.

The report suggests that some whales may well have been close enough to suffer temporary or permanent hearing damage.  In the most damning finding, it appears clear that monitoring for nearby animals was cursory at best, done only from small inflatable boats: Read the rest of this entry »

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:

Next week in Denver, the American Wind and Wildlife Institute and National Wind Coordinating Collaborative will be hosting their 10th Wind and Wildlife Research Meeting.  For the second time, I put together a research summary poster for the event (here’s the first one).  Most of the presentations at this meeting are focused on direct mortality (birds or bats hitting turbines) and habitat-disruption issues; in recent years, concerns about the sage grouse on the northern plains and the Fish and Wildlife Service’s new eagle permit process have also been hot topics.

As usual, my contribution is one of the few looking at the effects of the moderate noise around wind farms.  It offers an overview of the current state of our understanding of the ways chronic moderate noise can change animal behavior and communication, shift population structure, and increase physiological stress.  It includes data from studies on sage grouse, frogs, mammals, and songbirds, as well as discussion of other considerations, uncertainties, and future research needs.

Effects of chronic moderate noise on animal behavior and distribution

In recent years, there’s been a growing sense of concern in the ocean noise community about the worldwide emergence of plans for mining the seabed for a wide range of minerals.  Some of these plans are moving toward completion, as mining companies have solved the cost and technical complications and begun submitting actual project plans to regulators.  An early glimpse of this process has just emerged from New Zealand, where the EPA is now evaluating a permit to mine rock phosphate offshore from the South Island.  See this article in Pundit (a tamer Kiwi version of Huffington) for a very good summary of the process going on there.

In particular, Pundit’s Claire Browning notes that the first seabed mining proposal to come before the EPA was turned down, and she details some of the extravagant non-acoustic impacts of the current project—the process involves scooping up masses of seabed and dumping most of the material back, creating plumes of debris (including uranium and other heavy metals) in the water column.  All this in a Benthic Protected Area where no bottom-trawling is allowed.  Meanwhile, a consortium of environmental groups is stressing the insufficient acoustic and population assessments included in the application:

…the company had carried out no visual or acoustic surveys to establish what whales were in the vicinity, and there was no empirical data on noise that would be generated by the mining. Instead, CRP contractors had constructed a model extrapolating noise from a shallow-water mining operation, a model that, for example, did not take into account noise from pipes taking sediment 450 metres up to the ship – or back down.

“There are a number of potentially serious impacts on marine mammals. More rigorous environmental impact assessment would be needed to assess the severity of the impacts of this development,” said Ms Slooten.

It’s especially good to see that local watchdogs are thinking broadly about the potential acoustic emissions, including the sounds of material being pumped through pipes; our colleagues at Ocean Noise Conservation have been raising questions about such largely-ignored subsea industrial noise around oil and gas sites for several years.  Also interesting in the Pundit piece is a moderately deep dive into the question of how much the Kiwi EPA is taking the precautionary principle into account; the lack of concrete direction to do so was a controversial element of the statutory directions to the newly-formed agency, but it appears that its decisions are indeed deferring activities that carry uncertain risks to sensitive areas.  It’s worth noting that seabed mining may not always be a bad thing; much terrestrial mining has high environmental and social impact, with the resulting raw material shipped large distances to its eventual markets.  Such pressure may be relieved at times by moving offshore; in this case, the company’s website highlights the benefits of mining rock phosphate domestically rather than importing it from Morocco, the primary current source.  But of course, offshore sites need to be thoroughly assessed, and any new activity directed toward areas that will create minimal impact on marine life.

The State of New Jersey has gone to federal court to block a seismic survey planned for this month fifteen miles offshore.  The survey, funded by the National Science Foundation, received its final permits from the National Marine Fisheries Service last week; the permit (similar to those issued routinely for oil and gas exploration or Navy sonar training) allows the sound from the airguns to incidentally harass marine mammals, including the possibility of some permanent injuries.  The New Jersey Department of Environmental Protection is aiming to stop the surveys from commencing in the next week or so; they claim that this is a poor time of year to introduce potentially harmful or harassing sounds, that the surveys could disrupt local fisheries for scallop, flounder, and squid, and that the National Science Foundation should have undertaken a more comprehensive public comment and environmental assessment process.

UPDATE, 8/14/14: Mechanical issues have sidelined the survey for this summer; the National Science Foundation plans to carry out the survey next year instead, while local activists vow to push for more thorough analysis and public input.

The survey, by Columbia University’s research vessel the Marcus Langseth (left) would examine seafloor sediment, as part of research looking at how climate change has affected river runoff and deposition over the past sixty million years.  Some critics, though, seem to be conflating the purpose here with a broader initiative underway to open Atlantic waters for new seismic surveys exploring for oil and gas; those plans have stirred controversy in states up and down the eastern seaboard.

“We believe the timing of this program will be detrimental to various marine species that migrate and breed off the New Jersey coast and will negatively impact the commercial fishing industry that relies heavily on these resources,” said New Jersey DEP commissioner Bob Martin.  Similarly, Bob Schoelkopf of the Marine Mammal Stranding Center in Brigantine, was quoted as saying: “Right now, bottlenose dolphins are mating and giving birth off the coast of New Jersey. May and June are the birthing periods. They are totally dependent on their parents to provide nursing for the first two to four years of their life, and if the mother, for some reason, cannot catch fish to eat, she can’t produce milk.”  It’s not obvious from these statements whether there is another time of year that either would suggest for a survey such as this.

Meanwhile, the Asbury Park Press spoke to the project’s lead scientist, Rutgers geology professor Greg Mountain, likens the technology to medical sonograms, and says it will cap years of investigations using sea floor corings to recover ancient sediment. The goal is to understand climate and sea level changes over millions of years, information that will be critical to foreseeing future sea level change along the East Coast, Mountain says.

[Click through for more info on seismic surveys in general, and AEI’s quick take on this situation]

Read the rest of this entry »

AEI lay summary of:
Holger Klinck, Sharon L. Nieukirk, David K. Mellinger, Karolin Klinck, Haruyoshi Matsumoto, and Robert P. Dziak. Seasonal presence of cetaceans and ambient noise levels in polar waters of the North Atlantic. J. Acoust. Soc. Am. EL176, 132 (3), September 2012.

I somehow missed this study when it was published a couple years ago, but the findings are so striking that I can’t resist turning back the clock to cover it.  Researchers from Oregon State University and NOAA’s Pacific Marine Environmental Laboratory analyzed data from two hydrophones deployed for a year in some of the most remote areas of the very northern Atlantic Ocean, and found seismic survey airgun sounds to be a dominant presence, audible for 95% of each day for five months a year (and over half the hours for two more months).

Luckily for the fin whales who are the most populous marine mammal in these remote waters east of northern Greenland, they tend to show up toward the end of the summer airgun season, and concentrate their polar activity in the winter, when the airguns go silent.  But blue whales and a relatively few sperm whales like to be there in late summer, and must co-exist with the steady rumble of airgun sounds, which increase the ambient sound levels by an average of 5-10dB, and up to 20dB.  By contrast, the roar of storm-driven winter waves adds up to 12dB, and the calls of thousands of fin whales add up to 10dB.

The authors don’t speculate about the location of the seismic surveys being heard in the region, which lies well north of the Arctic Circle (the two sites are between 75 and 80 degrees north latitude; the Arctic Circle is at 66.5).  But it’s a straight, if rather long, shot from the North Sea oil fields between the UK and Scandinavia, with Norway’s offshore arctic developments a bit closer. I suspect that the offshore concentrations of red between Norway and the study sites are likely active oil fields, with heightened airgun activity; the dark red North Sea hosts one of the world’s highest concentrations of ongoing seismic surveys.

What’s especially discouraging about these findings is that this is one of the increasingly rare parts of the world’s oceans that is largely spared the scourge of shipping noise.  The more northern site lies close to a minor shipping lane between Norway and its remote arctic island outposts, but compared to the din of ships in most of the temperate latitudes (where shipping noise has roughly doubled in intensity each decade since the 1950s), this should be—or could—be an acoustic refuge. The map to the right shows the study areas, on the sparse fringes of the red cloud of global shipping routes. (Ed. note: Fish, which are not as wide-ranging as whales, and often use low-frequency sounds, are also likely affected by the increased background noise caused by airguns.)

The whales who visit seasonally seem to be putting up with the additional noise from seismic surveys; hundreds of blue whales are heard during 60-80% of hours in August and September, even as airguns continue to be heard nearly 100% of hours; the newly-arriving fin whales are heard close to half the time in those months, increasing to 70-80% of hours as their numbers climb to an estimated 6000 in mid-winter. Of course, at close range the whale calls are much louder than the distant airguns; but the steady hum of airguns at 5-10dB above what would otherwise be the background sound level can make it difficult for whales to hear their brethren across the dozens or hundreds of miles that they might otherwise communicate. As the authors note: “(D)uring the summer months. . . reverberation effects associated with the propagation of airgun signals often caused a continuous series of transient sounds.” 

The authors note that recordings made in the early 1970s show winter-time sound levels similar to those recorded in this study; that study, however, did not find the summertime increase that is now associated with the distant seismic surveys.

Eighteen months after a lawsuit challenged the latest 5-year authorization for the US Navy’s SURTASS-LFA low-frequency active sonar system, Federal Judge Elizabeth Laporte ruled in the Navy’s favor on nearly all counts.  And last week, the Navy agreed to do a Supplemental Environmental Impact statement that will address the key point on which she found in favor of the plaintiffs.

As reported here earlier, the Navy was authorized to deploy LFA sonar on four ships, though initially only two were so equipped, both generally deployed in the western Pacific, monitoring North Korean and Chinese vessels (in 2009, their presence spurred a multi-month spat with China). The legal challenge addressed here, filed in late 2012 by the NRDC and several allies, targeted both the Navy’s EIS and the National Marine Fisheries Service’s five-year incidental take regulations.  In her ruling last March, Judge Laporte sided with the Navy and NMFS on most counts.  Most centrally, Judge Laporte ruled that the relatively limited set of Offshore Biologically Important Areas (OBIAs) that should be avoided by LFA sonar was justified by the science, and was not, to use the legal-standard terms, arbitrary and capricious (by contrast, NRDC charged that the 22 OBIAs were “literally a drop in a bucket” within the 50% of the earth’s oceans open to LFAS deployment). In addition, several specific ways in which the Navy and NMFS limited OBIA protections were ruled valid, including using only seasonal OBIAs to protect sperm whales, and omitting harbor porpoises and beaked whales from OBIA protections because the sonar’s frequencies do not overlap their hearing ranges.  And, in several areas, Laporte also rejected claims that the Navy failed to use the most recent available evidence (this is a new angle of attack, one that Laporte showed some openness to in a related suit on the Navy’s mid-frequency active sonar plans).  In addition, she ruled that the Navy and NMFS did not fail to consider alternatives to LFAS, and did not fail to “take a hard look” at effects on non-marine-mammal species such as fish.

UPDATE, July 2016: A federal appeals court has overturned much of this ruling, suggesting that the NMFS failed to meet the “least practicable impact” standard by choosing to include only those 22 OBIAs as exclusion zones.  See details here.

However, in one area, Laporte found that the Navy’s EIS fell short: it failed to update its stock estimates for bottlenose dolphins around Hawaii based on a new study (released after the initial impact assessments were done, but before completion of the final EIS) that showed more bottlenose dolphins in waters around Hawaii than previously estimated (two exercises with the Pacific LFA ships occur near Hawaii).  Thus, the Navy’s impact estimates, using the old numbers, are too low.  In a final agreement approved by Laporte in late May, the Navy agreed to re-run its estimates in a Supplemental Environmental Impact Statement, to be completed by February 2015; if past is prologue, the Navy will run its new numbers and find that the impact is still negligible.  However, the LFA plan aims to impact no more than 12% of any regional stock of each species, and it may not yet be clear whether the new numbers will push impacts above that threshold (the earlier estimates peaked at 6% of the stock of Hawaiian bottlenose dolphins in offshore pelagic waters).

If that’s not enough legal reporting for ya, then click over to this post from January 2014 detailing the most recent round of lawsuits, filed against new 5-year permits for Navy training areas in US offshore waters.

The International Maritime Organization (IMO) has adopted the first-ever comprehensive guidelines on shipping noise.  The voluntary guidelines mark the first step toward a longer-term goal of bringing noise factors into planning for both ship design and shipping routes.

This marks the successful completion of a six-year process, largely spearheaded by NOAA, the US Coast Guard, and their German counterparts at IMO. The US Chamber of Shipping, a trade organization, has also been engaged from the start.  While the guidelines are voluntary, leading some observers to question their value, it is expected that many key players will begin to work with the guidelines in coming years. In general, the shipping industry is far more willing to design new ships to be quieter, than to retrofit older ships. Ed. note: one fascinating insight from the early IMO process was that global shipping noise may be dominated by relatively few unusually loud ships in each size class. 

In this ocean noise map created by NOAA, the darkest areas represent noise about 60dB above natural ambient levels

As summarized by NRDC, the new guidelines mark a milestone in ocean noise awareness on several fronts, as they:

• recognize that shipping noise can have short-term and long-term impacts on marine life, especially on marine mammals;
• call for measurement of shipping noise according to objective, available international standards;
• identify computational models for determining effective quieting measures;
• provide guidance for designing quieter ships and for reducing noise from existing ships, especially by minimizing the roar produced by ship propellers, in a process known as cavitation; and
• advise owners and operators on how to minimize noise through ship operations and maintenance, such as by polishing ship propellers to remove fouling and surface roughness.

UPDATE, 6/4/14: In 2012, the International Organization for Standardization (ISO) developed formal standards for the measurement of underwater sound from ships.  ISO standards provide detailed specifications that assure consistency in what is being measured (frequencies, reporting metrics), and how (distance from sound source, conditions, etc.).  Combined with the IMO guidelines, shipping companies now have the tools they need to provide clear information on the noise footprint of their vessels and the design choices they make to reduce noise; although neither the IMO nor ISO specify specific limits or targets for ship noise, they provide standardized ways of reporting on the noise of ships.  RINA Services, which provides a wide range of independent marine certifications, has just added a new voluntary notation, DOLPHIN, that combines the IMO and ISO reporting standards, and gives shipowners a third-party certification option to specify commercial vessels which have implemented solutions to minimize radiated underwater noise.

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.

Deepwater Wind, which recently won the first-ever competitive lease auction for US offshore wind, has signed an agreement with a consortium of environmental organizations that affirms its intention to minimize potential impacts on critically endangered Right whales. The wind farm’s location, in Rhode Island Sound, is host to foraging Right whales each spring; the agreement delays any pile-driving activity until after May 1, when whales have generally moved north.  In addition, pile driving later in the year will take place only during the day, when any lingering whales can be more easily seen.

The agreement marks an important step forward in marine conservation, with wind energy developers agreeing to key provisions that the Navy and oil and gas exploration companies have resisted: changing their operational schedule to avoid times of particular biological importance in a given area, and agreeing to limit loud noise-making activities to daylight hours.

The current agreement covers pre-construction activities, including pile-driving five foundations, for meteorological towers and perhaps test turbines (the press release does not specify). The Deepwater ONE wind farm will ultimately be home to 150-200 turbines; construction of that phase of the project will create a significant noise footprint, and we will hope that the company agrees to continued protective conditions at that time. A similar agreement by Deepwater for its smaller 5-turbine Block Island Wind Farm does cover the actual construction period; that press release does not mention daylight-only construction, but does delay construction until May. However, a broader agreement between environmental groups and several wind developers does include a provision precluding pile driving at night or in heavy fog; one hopes that this good-faith agreement will indeed be reflected in actual final operational plans. 

While recent years have seen an apparent reduction in the number of sonar-related strandings, one of the world’s hot spots for such tragedies saw a rash of strandings in recent days.  Two different stranding events occurred along the southern shore of Crete, the first involving 5-7 Cuvier’s beaked whales along a 16km stretch of coast, and the second occurring a few days later and 48km east, where three members of the same species came ashore.  In both cases, many of the animals were refloated and returned to sea (and unknown fates), while four whales died, including a fetus that was apparently close to term.

A NATO naval exercise, Operation Noble Dina, is ongoing in the area, involving US, Greek and Israeli forces. This part of the Mediterranean has been the site of several previous strandings, as noted by NRDC’s Michael Jasney:

For Greece, none of this is new. In 1996 and again in 1997, dozens of beaked whales of the same species turned up along the Peloponnesian coast; in 2011, they stranded on the island of Corfu as well as the east coast of Italy, across the Ionian Sea. In each case, navies were training with high-powered sonar in the area. Indeed, according to the Smithsonian Institution and International Whaling Commission, every multi-species beaked-whale mass stranding on record everywhere in the world has occurred with naval activities, usually sonar exercises, taking place in the vicinity.

One of the ongoing areas of contention between environmental advocates and the US Navy and federal regulators is whether sonar training (and naval live-fire and explosion exercises creating loud and potentially harmful noise) should be planned to avoid areas with known concentrations of marine mammals, especially those, such as beaked whales, that are especially sensitive to noise.  As it turns out, the area of this stranding is one of a large number of areas recommended as Areas of Special Concern for beaked whales by that the Scientific Committee of ACCOBAMS (Agreement for the Conservation of Cetaceans of the Black and Mediterranean Seas, a consortium of governments in the region).  As reported by a long-time chair of its Scientific Committee, the recommendation fell on deaf ears when presented to the full ACCOBAMS meeting of the parties last year; military preparedness was the explicit reason for the rejection.

In the wake of the two stranding events, Operation Noble Dina continues, but was moved 100km south of Crete—now outside the boundary of the proposed Area of Special Concern, yet apparently still able to complete its military preparedness mission.

Last fall, Dominion Virginia Power won the first federal lease for developing wind power off the coast of Virginia.  As with all offshore energy and Naval activity on the east coast, one of the first environmental concerns to be raised was what measures would be taken to minimize impact on the critically endangered North Atlantic Right whale. While their population has been more or less steadily rising since 1990, with only about 400 individuals, they remain vulnerable to any negative impacts, from ship strikes to increased stress levels, which may reduce reproductive rates and success. (See NOAA’s most recent stock assessment report for details; it notes lower reproductive rates than other Right whale stocks, and concludes that the population will be negatively affected if it loses more than 0.9 whales per year to human impact.)

With all this in mind, Dominion Virginia Power’s first commitments to the Virginia Offshore Wind Development Authority fell far short of what many had hoped.  The company agreed to limit installation activity of test platforms (meteorological towers and preliminary test turbines) during the period when whales are most apt to be migrating past the Virginia coast, but made no such commitments about later, and much more extensive, pile-driving for hundreds of turbines in the eventual wind farm.

“We’re happy to talk” with environmental groups, said Mary C. Doswell, Dominion Resources Inc.’s senior vice president for alternative energy solutions, though she noted, “we can’t overlook the costs of compliance.”

The company said they’d minimize their first-phase activities from late November to late March.  The whales spend the summers in a large area off the coast of New England and the Canadian Maritimes, and concentrate at birthing grounds off the coast of northern Florida in winter. NOAA maintains a reduced speed zone along the mid-Atlantic coast, to protect migrating Right whales, from Nov.1 to April 30, close to two months longer than the company set aside as their cautionary season; even the speed restriction is seen by some as a potential obstacle to offshore wind data collection.

UPDATE: See also this article from last fall, which suggests that Dominion plans only to erect a 2-turbine test platform, with full-scae development of 200 or more turbines on hold until costs come down for offshore wind construction.  Some wind advocates suggest that Dominion, which has fought renewable energy initiatives in the state, secured the lease largely to prevent others from developing a large offshore capacity.

In December, the Navy’s current five-year plan for training and testing activities around Hawaii and off the southern California coast were approved by NOAA regulators, covering the years 2014-2018.  The approval authorized incidental takes of marine mammals, including both widespread behavioral changes and close-range injuries and some deaths, as a result of sound exposure from sonar and explosives, as well as ship strikes.

Immediately after NOAA’s approval, environmental organizations filed suit in federal court in Hawaii, and this week, other organizations filed suit in a San Francisco federal court (the Navy pushed back in a brief statement).  It’s unclear from early press coverage how much overlap there is between the two; the Hawaii suit, led by Earthjustice, initially named just NOAA, but has been amended to also name the Navy as a defendant.  The San Francisco suit, led by the NRDC, targets NOAA, charging that federal regulators did not use “best available science” and that their finding of “negligible impact” violates the Marine Mammal Protection Act.

At issue in both suits is the shockingly large numbers of animals that are permitted to be affected, amounting to nearly 10 million behavioral responses, the potential for 2000 permanent injuries (including hearing impairment), and 155 deaths over the course of five years.  “This is an unprecedented level of harm,” Zak Smith, an attorney with the Natural Resources Defense Council, said. “In order to authorize these impacts on marine mammals, the service had to turn its back on the best available science.”

It’s important to note that while sonar has been the focus of most public concern, explosions during testing and training are predicted to cause most of the injuries and deaths.  The Navy and NMFS consider the estimates to be extremely cautious (ie far higher than actual likely impacts) for a number of reasons; see the bullet list in this earlier AEI post for more on why.

NRDC, Earthjustice, and the other plaintiffs continue to stress that the Navy can and should limit its activities in areas and times of particular biological importance to marine species; the lack of such “spatio-temporal restrictions” has been a bone of contention for many years, and this time, as in past rounds of permitting, the Navy and NMFS determined that such restrictions would yield little biological benefit.  A largely similar lawsuit filed in 2012, challenging NOAA permits for Navy training in the Pacific Northwest, ended up in a split decision, with the “best available science” ruling going against NOAA, but the large takes challenge (including the lack of exclusion zones, as well as faulty negligible impact ruling) falling short, with the court approving of NOAA’s analysis and actions.

UPDATE, 2/10/14: See this article from NRDC, outlining their reasons for this lawsuit and how it fits in with their 20-year history of focusing on ocean noise issues.

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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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AEI lay summary of:
Natasha Aguilar de Soto, Natali Delorme, John Atkins, Sunkita Howard, James Williams, Mark Johnson.  Anthropogenic noise causes body malformations and delays development in marine larvae.  Nature Scientific Reports, 3:2831.  DOI: 10.1038/srep02831 Download PDF

Just months after shipping noise was shown to cause dramatic behavioral changes in crabs, this new paper provides the first evidence that low-frequency seismic airgun sounds may trigger developmental delays and malformation in the larvae of shellfish.  Over the past decade or so, as researchers have looked more closely at behavioral disruptions caused by human noise sources, including temporary displacement of some fish stocks away from seismic surveys, there has been some concern that acute noise exposure from high-intensity sound sources such as airguns could also affect larval development.  If this were shown to be so, then regulators may need to consider protecting some vulnerable areas from intense noise exposure during seasons of key larval development.

This study exposed scallop larvae to recorded sounds of airgus, and compared larval development beginning after 24 hours of sound exposure and continuing until 90 hours.  This encompassed several stages of larval development, with 470-800 larvae examined at each sampling time.  

For the first day and a half, larvae exposed to airgun noise showed significant developmental delays.  At close to two days, the noise-exposed group appeared to be nearly as likely to be fully developed as the control group (upper right chart).  But, after passing the 48-hour mark, as the larvae moved into the next stage of development, those in noise lagged again; at 66 hours, all of the control larvae had completed the D-veligar development, while a large proportion of those exposed to noise did not complete this transition.  In addition, a significant proportion of the noise-exposed larvae began exhibiting physical abnormalities (localized bulges in the soft body of the larvae, but not in the shell).  By the end of the study, at 90 hours, an average of 46% of noise-exposed larvae showed malformations, ranging from 27%-91% in the four flasks being independently analyzed. (Ed. Note: I’ve reproduced five of the seven charts here, omitting samplings at 54hrs and 90hrs for the sake of better readability.)

The authors note that “the abnormalities observed here are comparable to those caused by chemical pollutants or water acidification, which have a clear impact on larval survival.”  They suggest several possible mechanisms for the abnormal bulges observed, and conclude that “although the exact mechanism is far from evident, physiological stress is likely the mediator for the developmental delays and growth abnormalities reported here.”  Further, the authors note that while behavioral responses vary widely both among and within species, stress response mechanisms are more generally similar across taxa, “suggesting that other invertebrates with similar growth patterns may be similarly affected.”

Of course, the nature of sound exposures in the ocean will be markedly different than those in this laboratory experiment, in which larvae were repeatedly exposed to a steady stream of 160dBrms impulses, once every three seconds for 24-90 hours.  In particular, the authors suggest that particle motion, rather than sound pressure, is the likely trigger for the effects, and acknowledge that several factors make it difficult to accurately predict the impact zone around an airgun in which particle motion would approach the 4-6mm/s RMS experienced by the sound-exposed larvae here.  In addition, the long periods of continuous exposure used in this testing procedure, while necessary in order to determine if there were indeed clear dose-response effects, may not be widely replicated in the wild.  Accordingly, the authors recommend that future research aim to establish the thresholds of exposure levels and durations that cause the effects seen here.

However, the authors stress that “given the strong disruption of larval development reported here, weaker but still significant effects can be expected at lower exposure levels and shorter exposure durations, especially if some ontogenetic stages such as the D-veliger prove to be particularly sensitive.”

The first ruling is in from the latest round of legal challenges to Naval training permits, and it’s a split decision.  You’ll need to click through to read the full post to get all the details, but here’s a preview of the conclusion you’ll find at the end:

It appears that the places that the court found NMFS falling short are in the details of how they prepare and analyze information, while the end results of the Navy activities and NMFS analysis and permits were upheld as valid. The court did not accept the plaintiff’s core concerns about the huge numbers of animals authorized to be affected (as litigated on the questions of protected habitats, mitigation measures, and cumulative impacts), deferring to the NMFS analysis that deemed even these large numbers to be acceptable, largely because most impacts are minor and temporary. The rulings that went against NMFS each appear to require simply more data analysis, which will then be fed into the same decision-making process that has been upheld as valid. 

In 2012, Earthjustice, NRDC, and others challenged both the 2010 Northwest Training Range Complex permits authorizing five years of mid-frequency active sonar and explosions at sea, and permits authorizing global deployment of low-frequency active sonar through August 2017. While earlier challenges targeted the Navy’s environmental analysis—or originally, the lack thereof—and ran aground when the Supreme Court ruled the Navy has broad discretion to weigh environmental safety against national security interests, this new round of lawsuits is directed at the National Marine Fisheries Service’s regulations and permits for the activities. 

In both cases, the primary focus of the challenges, at least as described in press releases, was insufficient protection of biologically important areas.  For several years, NRDC and others have stressed that Navy training ranges, which stretch along nearly the entire east and west coasts of the US, contain enough area for diverse training while setting aside some seasonal or year-round exclusion zones where training is avoided due to concentrations of marine animals.  Navy estimates of the numbers of animals likely to hear sonar or explosions, leading to either behavioral changes or injury, are alarmingly high, and the plaintiffs suggest that these numbers could be reduced significantly by setting some areas off limits, at least at key times. Unlike in previous challenges directed at the Navy itself, the plaintiffs did not seek any sort of injunction to halt the training exercises; rather, they asked that the court require the NMFS to revisit and revise their previous rules or authorizations in light of any deficiencies the court determined to be present.

As the NWTRC case moved into the argument phase, several specific challenges to NMFS procedures, analysis, and conclusions were raised and addressed. In a ruling issued by US Magistrate Judge Nandor Vadas in late September, the plaintiffs came away with at least a temporary win on several points, while the NMFS prevailed on several other fronts, including on the fundamental arguments about habitat protection and long-term impacts.  As in previous rounds of this legal battle, it appears that the end result will be Navy training continuing pretty much as it was before any of the legal challenges began—though with detailed analysis of potential impacts continuing to be pushed into new realms by the legal challenges.

The court ruled that the NMFS had improperly failed to include some relevant studies from 2010 and 2011 when issuing a 2012 Letter of Authorization and Incidental Take Statement, two years after the initial Five-Year Regulations were issued, and so did not rely on the “best available evidence” and likely underestimated the number of animals affected by Navy activity in its 2012 permitting documents.  In addition, the court ruled that the NMFS should analyze impacts not just over the five years of each planning cycle, but for a longer (unspecified) time period, because Navy training is considered to be a permanent, long-term activity.  Over the next month, NMFS will file a brief describing what they see as an appropriate scope and duration of any order to change their previous documents, and the plaintiffs will file a reply; presumably, the Court will rule shortly thereafter on specific remedies.

However, the NMFS prevailed on several substantial issues, including the primary one and two important related challenges.  On the central question of setting aside exclusion zones to better protect essential habitats, the court ruled that the NMFS had given such exclusions due consideration, and lawfully concluded that such exclusions would not be likely to reduce take numbers significantly.  Likewise, the court ruled that NMFS determination of no significant impact did not rely on insufficient mitigation measures (primarily visual observers) in making its assessment of likely harm; rather, NMFS determined that even before mitigation measures were implemented, the numbers of animals affected and the degree of impact did not pose long-term risks to local populations.  

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AEI lay summary of:
Southall, B.L., Rowles, T., Gulland, F., Baird, R. W., and Jepson, P.D. 2013. Final report of the Independent Scientific Review Panel investigating potential contributing factors to a 2008 mass stranding of melon-headed whales (Peponocephala electra) in Antsohihy, Madagascar.
Download full report or executive summary.
See IWC website for report and all supporting materials 

For the first time, a mass stranding appears to have been triggered by a relatively high-frequency mapping sonar; most previous strandings (though rare) have been associated with mid-frequency military sonars.  An international, independent scientific review panel (ISRP) of five well-known marine mammal researchers has concluded that a 2008 stranding event on the northwest coast of Madagascar was likely precipitated by an avoidance response to a multi-beam echo-sounder system (MBES) being used to map the seafloor.

Over a hundred melon-headed whales, deep-water foragers who normally live far offshore, became trapped in a shallow estuary one day after the MBES was active 65km off the coast; locals and international marine conservation organizations collaborated for three weeks to save floundering whales, with at least 75 confirmed dead.  The ISRP investigated all known possible causes for such events, and concluded that the most likely trigger was that the whales were moving away from the sonar, and became trapped in the unfamiliar surroundings of the narrow La Loza Bay estuary.  There, they found it hard to orient and navigate in the shallow, murky water; lack of food sources, stress/fatigue, and an accumulation of small injuries led to eventual death for most.

Acoustic modeling suggests that the whales would have been able to hear the MBES signals for at least 30km from the survey vessel, to near the island seen on the map to the right, 25km offshore, at which point they apparently continued moving toward shore until straying into the stranding zone.  Why the animals continued moving inshore after the sonar was no longer audible is unclear.  This is a species that normally lives only in deep waters; once the whales moved past the cliff near the survey area and into shallow shelf waters, they may have been quite confused, and further behavioral anomalies (including ending up in the estuary) may be unrelated to the survey sounds.

UPDATE, 10/10/13: This WaPo article includes some skeptical responses, centering on the uncertainties about other factors (before and/or after the MBES sound exposure) that may have contributed to the stranding, and concerns that the strong language of this report could lead to an over-reaction among regulators.  A spokesman for Exxon-Mobil, which helped fund the study and the initial stranding responses, said, “our contract vessel happened to be there in that time frame, but there are so many uncertainties in the area that we’re not sure it’s us.” Still, the company has changed its practices to avoid use of MBES near sharp cliff faces, since the panel speculated that echoes off the cliff may have confused the whales, sending them further inshore.

The ISRP report concludes that “this clearly appears to be an atypical event,” yet also stresses that the MBES system may pose previously unrecognized risks:

It is important to note that these systems, while regularly used throughout the world in hydrographic surveys, are fundamentally different than most other high-frequency mapping or navigational systems (ed. note: or fish-finding sonars). They have relatively lower source frequencies (12 kHz is within the range of likely best hearing sensitivity for all marine mammals), very high output power, and complex configuration of many overlapping beams comprising a wide swath. Intermittent, repeated sounds of this nature could present a salient and potential aversive stimulus.

Click on through for more details on the stranding, the ISRP report, and maps.

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