The sound of saving salmon

Harbor seals hover near the entrance to fish ladders at Maritime Heritage Park in Bellingham, where chum salmon bottleneck as they return each fall. Seals and sea lions have learned that salmon make easy meals at choke points such as these.

At high tide, near the mouth of Whatcom Creek, recent visitors to the hatchery at the Maritime Heritage Park in Bellingham might have heard an unusual sound.

Above the noise of the water rushing over fish ladders and the river crashing under the Dupont Bridge at the northeast end of the facility, you can hear it: a noise like a short burst of static, as though someone is about to turn on an intercom or use a walkie-talkie.

It comes irregularly, and that’s by design; that sound is a new GenusWave Targeted Acoustic Startle Technology (TAST) device meant to deter hungry seals congregating at the river’s entrance to the hatchery, where they’re preying on the chum salmon who are on the last leg of a long journey to return to their home river to spawn.

Chum salmon ready for spawning move within holding ponds at Whatcom Creek in Bellingham on Thursday, Nov. 12, 2020.

Through a contract with the Washington Department of Fish and Wildlife (WDFW) and with support from Bellingham Technical College (BTC), the GenusWave TAST device has been deployed for the last several weeks, just as the chum return has peaked. It’s deployed at high tide and monitored by two biological technicians with Oceans Initiative, a nonprofit dedicated to preserving marine life in the Pacific Northwest.

Brittany Palm-Flawd, faculty and hatchery manager with the BTC Aquaculture and Fisheries program, said that seals have been a growing problem in recent years.

“Region-wide, we have been seeing increases in seal populations, and a lot of the local seals really love to eat our salmon here,” Palm-Flawd said. “Once the salmon make it through the hurdles to get back to their native creek for spawning, they then have to deal with this surge of seal populations that are consuming them before they can spawn. So we’ve been working with multiple stakeholders to help tackle this issue of getting seals to stop eating our salmon.”

The TAST device is deployed at high tide, and emits sound at irregular intervals to keep pinnipeds guessing.

Developed at the University of St. Andrews in Scotland, the device is designed to deter seals by harmlessly inducing a flight response, at a volume and signal frequency that doesn’t also scare away the salmon trying to make their way upstream. The trial at Whatcom Creek follows a previous effort at Ballard Locks in Seattle, where Oceans Initiative deployed the GenusWave TAST earlier this year to discourage seals from feasting on salmon.

Though the results from the Ballard Locks trial are still being analyzed and uncertainty remains about the device’s long-term efficacy, so far it appears to be having a positive impact. At Whatcom, the effect is immediately apparent: several seals hovering near the entrance to the fish ladder Thursday swam away the moment the device was turned on, moving to an area about 50 meters downstream.

Andrea Mendez-Bye and Stephanie Reiss of Oceans Initiative lower the TAST device into Whatcom Creek on Thursday, Nov. 12, 2020.

That’s about the effective range of the device, said Stephanie Reiss, a biological technician with Oceans Initiative. She and fellow Biological Technician Andrea Mendez-Bye monitor the TAST while it’s deployed, observing and identifying the nearby pinnipeds and any continued predation on salmon.

“The majority of the seals that we see respond pretty clearly to the TAST,” Reiss said. “Before we turn it on we usually have anywhere from four to nine or 10 individuals in this area that we can see. By the time we turn it on the numbers dwindle sometimes to zero for a while, or one or two.”

And while it doesn’t completely stop pinnipeds from preying on salmon, at Whatcom Creek it does move them away from the most critical chokepoint, where salmon gather before making their way up the fish ladder. On Thursday, a small school of chum swam leisurely around the TAST while the device was turned on, the seals still stalking further downstream, kept away by the invisible wall of sound.

Chum salmon swim near the deployed TAST, which deters seals without disturbing fish in the area.

Mendez-Bye and Reiss said the response to the TAST from visitors to the hatchery has also been positive, as people recognize the need to responsibly manage seals and sea lions to help recover salmon. Mendez-Bye noted that it’s rare to see such obvious results during a trial such as the one currently taking place at Whatcom Creek, but the way the seals retreat the moment the device is turned on is a good sign.

Palm-Flawd of BTC said the device has been “very successful” at keeping seals away since it’s been deployed at the facility, benefitting this year’s spawning efforts.

This effort to manage pinniped predation is just one promising component of wildlife managers’ efforts to curb predation on already-troubled salmon runs around the state, coinciding with other efforts to restore native salmon habitat, reduce barriers to fish passage, and responsibly produce hatchery fish while also managing recreational and commercial harvest.

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