Killer whale tagging and acoustic studies provide increasing details

L-84, a 25-year-old male orca named Nyssa, has been carrying a satellite transmitter for more than two months now, allowing researchers to track the movements of Nyssa and any whales traveling with him.

Typical of recent travels by the L- and his entourage, the whales traveled north and south of the Columbia River from April 14 to 20.
Typical of recent travels by L-84 and his entourage, the whales traveled north and south of the Columbia River from April 14 to 20. // NOAA map

Nyssa, the last survivor of his immediate family, tends to stay around L-54, a 38-year-old female named Ino, and Ino’s two offspring, L-108 (Coho) and L-117 (Keta). Often, other members of L pod are with him, and sometimes K pod has been around as well, according to observers.

The satellite tracking is part of an effort to learn more about the three pods of Southern Resident killer whales, which are listed as “endangered” under the Endangered Species Act. That means they are headed for extinction without changes that increase their rate of survival.

The Navy, which has long been training off the West Coast, has been supporting some of the research in hopes of finding ways to reduce inadvertent harm from its active training in that area, officials say.

Over the past week, the whales moved well offshore near Grays Harbor, then returned to the entrance of the Columbia River. NOAA map
Over the past week, the whales moved well offshore near Grays Harbor, then returned to waters at the entrance of the Columbia River. // NOAA map

Since L-84 was tagged on Feb. 17, the whales have been generally traveling up and down the Washington and Oregon coasts. At various times, researchers — including biologists from Cascadia Research — have been able to get close enough to collect fecal samples from the whales and scales from fish they are eating. The goal is to determine their prey selection at this time of year. Chinook salmon are their fish of choice, but they will eat other species as well.

Winter storms and waves create challenging conditions to study the whales, but the satellite-tagging program has helped researchers find them, said Brad Hanson, who is leading the study for NOAA’s Northwest Fisheries Science Center.

Brad told me that he is thrilled that the satellite tag on L-84 has remained in operation so long, allowing more and more data to be collected. Satellite tags are designed to fall off after a time, and the compact batteries will eventually run out of juice.

“This is the latest (in the season) that we have had a tag on a Southern Resident,” Brad said. “Who knows how long it will last? The battery will probably make it until the end of May, and the attachment looked good the last anyone saw the tag.”

The research is not just about figuring out where the whales travel, Brad said. It is about finding out which areas are important to them.

While tracking the whales by satellite, the research is being expanded with the use of acoustic recording devices deployed in key locations along the coast. The goal is to find ways to track the whales with less intrusion. But how does one know where they are located during periods when the whales go silent — sometimes for days at a time? Those are the kind of questions that researchers hope to answer by correlating the acoustic and satellite data together, Brad said.

With Navy funding, 17 recorders are now deployed along the coast, including one recorder many miles offshore to pick up whales that get out into the deep ocean.

“We have certainly reduced a lot of the mystery,” Brad said. “The main issue — and what the Navy is interested in — is how they mitigate for marine mammal presence.”

Knowing that killer whales can be silent, the Navy has largely relied on visual sightings to determine the presence of the animals. During high waves, that may not be a reliable method of detection. The answer, based on tracking the whales, could be to move the training operations farther offshore — beyond the continental shelf, since the Southern Residents appear to rarely go out that far.

The Southern Residents are among the most studied marine mammals in the world, yet it is not entirely clear why their population is not recovering. An upcoming effort will begin to look at whether new information about the health condition of the whales can be teased out of existing fecal and biopsy samples or if new methods of study are needed to assess their health.

Meanwhile, raw data from various studies continue to pour in, challenging NOAA researchers to focus on specific questions, complete their analyses and share the findings in scientific reports. According to Brad, ongoing staff cutbacks makes that final step even harder than it has been in the past.

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