Science panel says effects of
seismic surveying still unclear
By MARK HIBBS
Coastal Review Online
industry officials have repeatedly dismissed claims that seismic
surveying for offshore gas and oil can have ill effects on marine
mammals, but coastal scientists say loud man-made noises change animal
behavior and more work needs to be done to be sure sensitive species
aren’t harmed by seismic survey activity.
seismic surveys are performed aboard vessels that transit the ocean
along grid patterns. Each boat tows an airgun that releases compressed
air into the water to create sound waves and arrays of sensors that
detect the reflected sound waves as they bounce off subsurface rock
layers at the bottom of the ocean. The information collection is used
to create 3-D maps that scientists analyze to pinpoint likely oil and
natural gas reserves and the safest and most efficient drilling
National Oceanic and Atmospheric Administration’s Fisheries offices,
also known as the National Marine Fisheries Service, or NMFS, recently
filed notice on four requests from companies that are planning seismic
surveys of the Atlantic Ocean for oil and natural gas. For the surveys
to begin, these companies must get permits to incidentally harass
animals protected by the federal Marine Mammal Protection Act.
act generally prohibits “taking” of marine mammals in U.S. waters by
any person and by U.S. citizens in international waters. NMFS defines
“taking” as harassment, hunting, capture or killing, or attempting to
harass, hunt, capture or kill any marine mammal. The Marine Mammal
Protection Act defines the term “harassment” to mean “any act of
pursuit, torment, or annoyance,” which has the potential to injure or
disturb a marine mammal or marine mammal stock in the wild by causing
disruption of behavioral patterns, including but not limited to,
migration, breathing, nursing, breeding, feeding or sheltering.
said it would consider input from the public in making its final
determinations to issue or deny the permits, which are also based on
the expected effects on marine mammal populations. The agency may
authorize the incidental taking of “small numbers” of marine mammals if
the taking will have no more than a negligible effect on the species or
stock, but the questions remain: How many is too many and what is
industry representatives often cite a 2014 statement by the federal
Bureau of Ocean Energy Management, or BOEM, that seismic surveys in the
Atlantic outer continental shelf leasing area will have no measurable
effect on fish or marine mammal populations. BOEM said “there has
been no documented scientific evidence of noise from airguns used in
geological and geophysical seismic activities adversely affecting
marine animal populations or coastal communities.”
responsibilities include managing the nation’s offshore resources to
ensure that exploration and development activities are conducted in a
safe and environmentally sound manner. That includes developing
environmental documents throughout the five-year lease-sale processes
under the terms of the Outer Continental Shelf Lands Act and the
National Environmental Policy Act. BOEM says its environmental
stewardship uses the best available science.
to BOEM, seismic surveys in the Atlantic “should not cause any deaths
or injuries to the hearing of marine mammals or sea turtles.” William
Brown, chief environmental officer for BOEM, has said claims to the
contrary are “wildly exaggerated and not supported by the evidence.”
including members of a panel of scientists that was a part of the N.C.
Coastal Federation’s daylong forum, "Shaping Our Economic Future:
Offshore Drilling in N.C.," held Friday, July 31, in New Bern, say
studies have shown that loud noises can affect marine mammals as
individuals. More research is needed to determine whether those effects
are severe enough to reduce marine mammal stocks, the scientists said.
noise affect wild animals? It has known effects on humans,” said Doug
Nowacek, an associate professor at Duke University and a member of the
science panel at the forum.
said the majority of studies have found effects on individual fitness
from noise, including altered vocal behavior, reduced abundance in
noisy habitats, changes in vigilance and foraging behavior and changes
to the structure of ecological communities.
can and does impact wildlife,” he said. “Seismic airguns are the
loudest sound source humans use in the ocean and noise continues
effects of that continued noise between pulses are where regulatory
environmental studies have, so far, come up short, Nowacek said, adding
that studies have also underestimated the size of the area affected by
“There is a fundamental mismatch between the BOEM analysis and the potential area of impact,” Nowacek said.
American Petroleum Institute says the sound from offshore seismic
surveys is comparable to the sound of a sperm whale echo-locating for
prey. They report that the sound is also similar to naturally occurring
and other man-made ocean sound sources, including wind and wave action,
rain, lightning strikes, marine life and shipping operations. Survey
operations are normally conducted at a speed of about 5 knots or 5.5
mph and, as a result, the sound does not last long in any one location,
according to API.
said an experiment in 1991 known as the Heard Island Feasibility Test
showed that low-frequency sounds travel extremely well throughout the
world’s oceans. During that test, an acoustic source lowered from a
ship near Heard Island in the southern Indian Ocean was used to
transmit coded signals that were detected by hydrophones throughout the
long distances low-frequency sounds can travel combined with the
ecological sensitivity of the area marked for seismic surveying could
be enough to affect a number of species already of concern, including
various whale species, scientists said.
Read, a marine biology professor at Duke University and another member
of the science panel at the forum, said knowledge of marine mammals
offshore of the continental shelf break in the mid-Atlantic and South
Atlantic is “very poor” and that more research is needed. He said the
waters of the proposed lease program and seismic survey areas support a
diverse group of whales and dolphins. The group includes seven species
of baleen whales, 23 species of toothed whales and four species of sea
turtles. Ten of these 34 species are listed as threatened or endangered
under the Endangered Species Act of 1973.
North American right whale is one of the species of most concern. Read
said its status is “precarious,” with only 476 known to be alive in
2011 and three documented deaths so far this year.
“Seismic exploration creates another stress,” Read said.
this year, NMFS proposed expanding the designated critical habitat for
the endangered North Atlantic right whale to include areas that support
calving and nursing. The rule would expand the critical habitat to
nearly 30,000 square nautical miles, including northeast feeding areas
in the Gulf of Maine/Georges Bank region and calving grounds from
southern North Carolina to northern Florida.
migratory corridor for North Atlantic right whales follows the Eastern
Seaboard, including waters off the N.C. coast. The whale’s historical
association with the central N.C. coast is reflected in the official
Carteret County seal, which includes images of two right whales.
also expressed concerns regarding Cuvier’s beaked whales, sometimes
called “goose-beaked whales,” and pelagic bottlenose dolphin, both of
which are also protected under the Marine Mammal Protection Act.
Beaked Whales are deep-diving whales particularly susceptible to some
man-made sounds, Read said. Off Cape Hatteras, they make dives to
depths of up to 2,800 meters and with durations of up to 98 minutes.
pelagic bottlenose dolphins make their home off Cape Hatteras, an area
of high species diversity because of the confluence of the warm Gulf
Stream and the colder waters of the Labrador Current.
Brown noted in a March publication, “Science Notes,” that the highest
numbers estimated for taking of a particular species are for the
bottlenose dolphin, as also noted in the bureau’s environmental review
of seismic surveying activities in the Atlantic. That review estimated
potential for Level A takings – potential injury – of up to 11,748
individual bottlenose dolphins a year from airgun surveys and potential
for up to 1.15 million Level B – potential disturbance or behavioral
disruption – takings. The numbers were “highly overestimated to err on
the side of protection,” according to Brown.
Brown also says more research is needed.
1998, BOEM has invested over $50 million on protected species and
noise-related research, including marine mammals. We have also convened
workshops for acoustic experts to help us identify questions for future
research. But BOEM needs to keep looking – hard and well – for
adverse effects of offshore oil and gas activities on the environment,
including sound. And we have asked our environmental studies program to
make this a priority,” according to Brown.
article is provided by Coastal Review Online, an online news service
covering North Carolina's coast. For more news, features, and
information about the coast, go to www.coastalreview.org.)