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So far, sonar has not been linked to orca death

February 18th, 2012 by cdunagan

When one of our resident killer whales, L-112, was found dead north of Long Beach on Feb. 11, people wondered immediately if the death might be related to a sonar incident reported a few days before.

Could the two events be linked or could the timing be just a coincidence?

The two-year-old killer whale, L-112, was laid out after death and prepared for a necropsy.
Photo by Cascadia Research

So far, I have been unable to find a ship that was deploying sonar off the coast. At the same time, it appears highly unlikely that L-112 could have been injured by sonar in the Strait of Juan de Fuca and then somehow swam out of the strait and down the full length of the Washington coast, succumb to death and then wash up on the beach, all in less than five days.

New evidence may come to light, but for now I would caution that we need to wait for an investigation by the National Marine Fisheries Service and not jump to conclusions over our concerns about sonar.

I discussed the investigation with marine mammal expert Lynne Barre of NMFS. She said the endangered listing of Southern Residents has heightened interest in all killer whale strandings, particularly unusual deaths like that of this 2-year-old female orca.

Lynne seems to confirm the idea that the investigation will proceed along three tracks. First, there’s the physical condition of L-112, as will be determined through careful examinations. Second, there’s the question of where L-112 and her family group were located during the time of injury. And, third, investigators need to locate ships with sonar capabilities and determine whether any of them had been using them in the time period in question.

Jessie Huggins of Cascadia Research and Dyanna Lambourn of the Washington Department of Fish and Wildlife provided an initial report from the necropsy:

“The whale was moderately decomposed and in good overall body condition. Internal exam revealed significant trauma around the head, chest and right side; at this point the cause of these injuries is unknown.”

Jessie told me that the whale was probably dead two to four days before it washed up on the beach. Trauma to the head was consistent with a blunt force, such as a boat collision or an attack by another large animal. The report mentions the prospects for what researchers may learn from various tissue samples taken from the whale.

Of particular interest to the sonar question is the skull, which has been frozen for the time being. Lynne Barre said it will undergo a CT scan with the hope of obtaining information about the condition of the inner ear and the delicate tissues involved in echolocation. Damage to those tissues could be an indication of trauma from a sound source, but experts will need to account for any decomposition after death. These issues are more complicated than they might seem.

As for the location of L-112 and her family, that probably will never be known unless one of the hydrophones picked up and recorded calls from L pod. Scott Veirs, associated with OrcaSound, has been working tirelessly the past few days to locate any orca sounds that may have been picked up throughout the area.

Scott has noted that killer whale calls consistent with K and L pods were picked up on two hydrophones in the San Juan Islands on Monday, Feb. 6, just 18 hours after a Canadian frigate, the HMCS Ottawa, transmitted loud pings throughout the area (Water Ways, Feb. 11). The two hydrophones picked up the sounds one after the other, suggesting that those whales were heading south toward the Strait of Juan de Fuca (OrcaSound, Feb. 8).

The next day, Tuesday, Feb. 7, some members of K and L pod were spotted in Discovery Bay between Sequim and Port Townsend, according to reports to Orca Network. Nobody can remember seeing Southern Resident killer whales there before. Could they have gone into the bay one day earlier, seeking refuge from the sonar? We may never know.

But if we’re talking about the death of L-112, subsequent IDs of the whales in Discovery Bay suggest that the group probably did not include L-112 or her family. I’m still trying to learn which whales likely would have been with L-112 around the time of her death. But chances are she and her family were out in the ocean when all this excitement was taking place in Puget Sound.

So that leaves the question of whether a ship could have been using sonar off the coast when L-112 was within range. I have been in touch with both U.S. and Canadian Navy public affairs officials, and both have denied that their ships were using sonar in the ocean during this time.

Lt. Diane Larose of the Canadian Navy confirms that two sonar-equipped Canadian Navy ships, the HMSC Ottawa and the HMCS Algonquin, were out at sea before entering the Salish Sea at the time of Exercise Pacific Guardian. But neither ship deployed their sonar before reaching the Salish Sea on Feb. 6, when Ottawa’s pinging was picked up on local hydrophones, she said. Navy officials say they followed procedures to avoid harm to marine mammals and have seen no evidence that marine mammals were in the area at the time.

A lot of gaps remain to be filled in, including the source of an unusual explosive-type sound at the beginning of the hydrophone recording that includes the Ottawa sonar, which Scott Veirs discovered (OrcaSound, Feb. 6).

Lynne Barre of NMFS agreed that the best thing for now is to wait until the investigation begins to answer some of the lingering questions. Sometimes the cause of death may include contributing factors, such as weakened immune systems that lead to disease that ultimately lead to a physical injury of some kind.

This is the third dead killer whale to be found in the vicinity since November. The others were a newborn calf from an offshore group of orcas and a very decomposed adult orca from the offshore population.

In all the discussions about sonar, we should not forget that the loss of this young female killer whale is significant for a variety of reasons. I remember the optimism that came with her birth back in the spring of 2009. See Kitsap Sun, March 5, 2009. L-112 also was one of the orcas who received two names, in this case Sooke and Victoria, because Ken Balcomb also named some whales at the time. (See Water Ways, Aug. 25, 2010.)

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3 Responses to “So far, sonar has not been linked to orca death”

  1. Scott Veirs Says:

    Great synopsis, Chris. Has the Canadian Navy said whether or not the impulsive sounds recorded minutes before the sonar pings were first heard were in any way related to the Ottawa’s training exercise?

    Also, let’s not forget to ask both Navies whether or not they generated any sounds along the U.S. or B.C. Pacific Coast during late January and the first two weeks of February. Until those impulsive sounds heard in inland waters are determined to be unrelated to military activities, I think the extensive trauma L-112 suffered should motivate us to ask about any underwater detonations that may have occurred on the outer coast.

    Finally, Monika Wieland’s blog post last Wednesday —
    http://www.orcawatcher.com/2012/02/sad-story-of-l112.html
    – offers some clarity about L-112′s relatives and her importance in the demographics of L pod.

  2. cdunagan Says:

    Thanks, Scott. As you know, I’ve inquired about the explosive sounds just before the sonar commenced. And, at your suggestion, I’ve extended the inquiry to the weeks before the Navy’s exercise.

    As you’ve mentioned to me, there could be some alternate explanations for the sound. I will continue to pursue this, but I did not want to delay this blog post any longer.

    While I’m at it, I want to thank you again, Scott, for your continuing efforts to piece together the disparate information from the world of underwater sound.

  3. Robert Dashiell Says:

    Sonar is always seems the first thing blamed when a whale washes ashore.

    Orca Network, Seattle Times … sonar is in headlines although no investigation or analysis has been conducted.

    Sonar might be involved, but sonar doesn’t do to a whale what is visible in the photograph.

    Hundreds of whales (and other water mammals) have historically been recorded washing ashore in the United States. Those records go back pre-Civil War, and sonar wasn’t invented until 1918.

    The not too distant USS SHOUP accusations of Navy sonar being responsible for Straits of Juan de Fuca porpoise deaths didn’t stand up to scientific and investigative scrutiny.

    Good article. Let’s see what the investigations and science reveals.

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