What About Sea Otters & Seismic Blasts?

Editor’s NoteCarol Georgi is the California Central Coast marine Sanctuary Alliance Coordinator.  She is active in halting the proposed PG&E Seismic Testing proposal along the Central Coast.  Her concern, as shown in this letter to the US Fish and Wildlife Service, is how the proposed testing will impact the local population of sea otters. 

October 25, 2012

U.S. Fish and Wildlife Service

Diane Noda, Field Supervisor

Electronic mail: R8_SSO-IHA_Comment@FWS.gov



They Can’t Protect Themselves  http://oceanarmor.org

Re: Central Coastal Seismic Imaging Project

PG&E’s request for Incidental Harassment Authorization (IHA) and permit for incidental take of Sea Otters

Dear Diane Noda,

The California Central Coast Marine Sanctuary Alliance sends this letter because we are seriously concerned for the welfare of Southern Sea Otters during PG&E’s Central Coastal California Seismic Imaging Project. PG&E is not mandated to use high energy seismic testing; alternative technologies need to be considered. Please hear our concerns, read the documented studies, and make the choice of no permit to PG&E for IHA and take of sea otters.

We find the Sea otter study paid for by PG&E unacceptable with its treatment of sea otters because they are not being protected. Evidently, the researchers will monitor how the sea otters may move away or experience injury or stress while trying to dive for food in the testing area.

We are surprised and seriously concerned that 60 sea otters have already been captured, tested, tagged, surgically implanted with two devices, and returned to the testing area for a dangerous experiment: “How they are going to react is the million-dollar question,” said Tim Tinker, lead researcher for the tagging project with the U.S. Geological Survey. Read full article by David Sneed. http://www.sanluisobispo.com/2012/10/20/2268771/sea-otters-earthquake-tests.html

A 2005 permit: #MA672624-16 USFWS was used for this recent harassment of 60 sea otters. This is a general permit reauthorized from 2005 for Sea Otter research and we do not understand how this permit can be used for this specific project. Does this permit authorize the surgical implants?  Watch implanting procedure in this KSBY TV video.  http://www.ksby.com/videoplayer/?video_id=21629&categories=581%2C694


California did not mandate PG&E to use high intensity 250 decibels (dB) acoustic seismic technology. Alternative technologies to seismic airguns exist. http://www.okeanosfoundation.org/assets/Uploads/Airgun.pdf

PG&E’s proposed acoustic blasting will harm marine sanctuary resources. The testing area has been approved eligible for marine sanctuary designation since 1990, and sits between the Channel Islands Sanctuary and the Monterey Bay Sanctuary. PG&E states in their EIR, “Sound will travel hundreds of miles and still be 120dB as far away as 58.95 miles according to PGE report.” The damaging acoustic pressure waves will travel into both National Marine Sanctuaries and be 120dB or stronger. Here are the Monterey Bay National Marine Sanctuary comments to the draft EIR:


PG&E’s EIR does not explain how airguns can injure and kill mammals.

Sonic blasting with airguns creates acoustic shock waves that travel underwater in the ocean. When the wave reaches your skin, it would pass through you. Little of its power would be reflected because your body’s density is similar to that of the water.

The shock wave would hit the air-filled pockets of your body and instantly compress the gases there, possibly resulting in blocked blood vessels, ruptured lungs, torn internal tissues and even brain hemorrhaging. Waves hitting the surface of the water or the bottom ground would bounce back, inflicting even more damage.   http://science.howstuffworks.com/explosion-land-water1.htm

Please read “Underwater Blast Injuries by Dr. P.G. Landsberg MD for more details of injury and death caused by acoustic shock waves. http://www.scuba-doc.com/uwblast.html

PG&E’s proposed seismic survey for box 4 uses arrays of 18 air guns pulled behind a boat following a grid pattern blasting 250 dB every 15 seconds around the clock for 12 days.

4 impacts a minute, 40 impacts in 10 minutes, 240 impacts in 1 hour, 5760 impacts in 1 day (24 hours), and 69,120 in 12 days would mean sea otters could not dive to gather their food.


PG&E states in the EIR that fish and other marine life will survive because they will leave the blasting area. This statement implies staying in the blast area will result in death, and ignores the shellfish, such as abalone and other marine life that cannot move quickly and leave. Thus, the marine life, including fish eggs, larvae, plankton, etc. will be destroyed within the blasting area.

PG&E plans to create a 160dB received sonic wave safety radius around the blasting area, including coming to the shoreline where people are recreating in the ocean. The US Navy determined a man’s threshold is 145 dB before internal tissue damage occurs. Navy study: http://www.surtass-lfa-eis.com/DiverStudies/index.htm


PG&E must consider public safety and more recent research showing 160 dB are not safe for most marine mammals.

Cummings found that harbor porpoises can only withstand up to 120dB and may not be able to get out of the bay inlet. Beluga whales are also are sensitive to more than 120dB.

Jim Cummings 
Executive Director, The Acoustic Ecology Institute, Santa Fe, New Mexico, US. E-mail: jim@acousticecology.org; Web: AcousticEcology.org

The January-February 2010 MPA News article http://depts.washington.edu/mpanews/MPA112.htm

“The 160-dB “safe” criterion noted in the article and widely used in mitigation plans likely represents roughly the sound level at which half the population will be expected to change its behavior in noticeable ways.  Unfortunately, the correlation between sound level and behavioral disruption is not at all linear.  Many individuals (and some species, particularly harbor porpoises and beluga whales) respond with aversion or foraging disruptions at much lower levels, down to 120dB.  There will always be a subset of a population that is more sensitive to noise.” 

Lindy Weilgart 
Research Associate, Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada.  E-mail: Linda.Weilgart@dal.ca

The November-December 2009 MPA News article (MPA News 11:3) on seismic surveys and MPAs resulted in a letter from Lindy Weilgart, PhD stating that “whale and fish disturbance is well documented at receive levels of 130 decibels (dB) and below—in contrast to the 160-dB threshold used at Endeavour, which is 1,000 times louder.”

“It is time to seriously research and promote more benign airgun alternatives such as, perhaps, controlled sources, passive seismic  [the detection of natural low-frequency earth movements], electromagnetic surveys, etc. – especially in sensitive habitats.”

We find the CA State Lands Commission response to the welfare of the Southern Sea Otters unacceptable, and as written, will put about 702 (25% of state’s total) of the Southern Sea Otters in jeopardy from the proposed seismic tests, EIR page 4.4-23 states 702 sea otters in project area.

Sea otters have been protected by law since 1911 and are protected as a threatened species under the 1972 Endangered Species Act. There is a small population of sea otters along the coast of central California.

If the sea otters are to remain within the testing area, the question is: What intensity (decibels – dB) of seismic testing can sea otters tolerate when diving for food

We find the following statement unacceptable and lacking knowledge and concern of sea otters diet and behavior.

“The NMSF Level A threshold for cetaceans (180dB) was used as the Level B threshold for sea otters. Because sea otters have the ability to avoid immersion of their heads and ears, this Level A noise level was considered to be appropriate for assessing the extent of disturbance (Level B harassment) to Southern sea otters due to noise.

The above response assumes sea otters can tolerate the 180 dB level because that is what they expect cetaceans to tolerate. Sea otters are not cetaceans, and their level of decibel tolerance is probably closer to that of humans when diving, about 140 dB or less.

We are concerned that your agency does not fully understand the impacts of acoustic pressure waves created by 18 airguns hitting mammals every 15 seconds day and night for 12 days. All parts of a mammal’s body will receive internal tissue damage, especially the torso and head, damage is not restricted to loss of hearing.

One only needs to learn about the sea otters diet and behavior to understand that leaving them within the high seismic testing zone will result in their death. Death will occur from the 250dB sonic blasts every 15 seconds, 24-hours a day for 42 days. Or death will occur from hyperthermia or starvation because of behavioral changes caused by the blasting.

Since the Southern Sea Otter’s common habitat is within kelp forests, we urge you to also protect the kelp forests. We are also concerned about the female sea otters, many of which will be pregnant in December. Pregnant sea otters and pups need no high intensity seismic pressure waves hitting them every 15 seconds day and night for 12 days.

According to the Central Coastal CA Seismic Imaging Project EA # Southern Sea Otter: Sea otters are most common in and around kelp beds and open water areas support substantially fewer adults. Kelp habitat provides territories and home range areas for male and females and sea otters will regularly be found in the same area over an extended period. Open water areas can and do have large numbers of otters on a regular basis, but the distributions can shift. It is believed that some of the highest densities continue to be found in open water habitat, such as Estero Bay, Monterey, and offshore of Pismo Beach (Figure 3-11) (M. Harris, pers. comm., 2011).

Death by Seismic Testing

Sea otters are not comparable to whales in determining the level of seismic blasts they can withstand. They should be exposed to no more intensity than would be recommended for humans.



Death by Hyperthermia

Sea otters need to eat about 25% of the weight in food each day in order to retain their body temperature as they have no blubber. Not being able to dive to get their food due to intense seismic blasting will result in them not eating enough to maintain their body temperature.


Death by Starvation

Sea otters spend much of their lives in the water and can dive up to 330 feet when foraging for food. The reason they dive is that the food is on the bottom of the ocean. Therefore, the intensity of the seismic blasts will determine if the sea otters can tolerate diving for their food.

Sea otters eat many kinds of invertebrates, including clams, snails, sea stars, sea urchins, crabs, squid, octopuses and abalone. This food lies at the bottom of the ocean, where they also pick up a rock. They carry the food and the rock up to the surface. Then they use the rock or other objects to pry and to hammer them open.


We respectfully ask you to deny the IHA and permit to PG&E for the proposed seismic tests

Not rushing forward with these high intensity seismic tests will give the peer group and PG&E time to review and evaluate the land tests and the low level ocean tests. After this review, scientists can learn what alternative technology can be used to protect our marine life ocean resources, especially sea otters.

Our ocean life and marine food supply are too valuable to recklessly destroy. Please apply the Precautionary Principle as you make your decisions.

If you choose to permit the seismic testing, you must take the necessary steps to protect the sea otters, even if it means removing them from the project area and requiring PG&E to pay for the necessary removal and relocation.

We are concerned with your monitoring plans that allow the high intensity seismic decibels to be increased if the sea otters appear undisturbed, and we are concerned with your lack of post-activity monitoring plans. Tissue damage to mammals may not be noticed immediately, and the bodies may wash ashore during the weeks following the seismic testing. For example, during and in the weeks following the low energy seismic testing, many birds died, and many mammal’s bodies washed ashore—dolphins, seals, sea otters. However, no monitoring was in place to collect data.

Leaving the otters for a science experiment does not protect the sea otters of California. Southern sea otters (Enhydra lutris nereis), also known as California sea otters, were listed as threatened in 1977 under the Endangered Species Act.  Reduced range and population size, vulnerability to oil spills, and oil spill risk from coastal tanker traffic were the primary reasons for listing.  As a consequence of their threatened status, southern sea otters are also recognized as depleted under the Marine Mammal Protection Act.  Under state law, southern sea otters are “fully protected” mammals. http://www.fws.gov/ventura/species_information/so_sea_otter/index.html


Thank you for considering these comments,



Carol Georgi, Coordinator

California Central Coast Marine Sanctuary Alliance

Categories: nature, Seismic Testing, Southern Sea Otters, Sustainable Seafood

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