PORT ANGELES, Wash. — River otters always leave the water to poop. So if you want to catch them, you’ve got to head to the bathroom.
Kim Sager-Fradkin is head wildlife biologist for the Lower Elwha Klallam Tribe. She’s out checking a series of traps, set up near what are called “otter latrines” along the banks of the Elwha River with her intern Selena Gray. The latrines, Sager-Fradkin explains, “Function as bathrooms but also as social congregation sites and scent marking sites. So multiple otters will use a single latrine and any individual otter will use multiple latrines up and down the river.”
Think: restroom stops along the freeway. But instead of funky smells and toilet paper on the floor, otters prefer to relieve themselves on leafy green river-front property. Selena Gray is standing near a trap site surrounded by mossy covered rocks, which she says otters prefer, just like some folks want quilted toilet paper.
Part I (Tuesday): Scientists are getting the “before” shot of the Elwha so they can see how things change once the river is dam-free.
Part II (Today): Keeping track of river otters to better understand a changing river and its impact on the forest ecosystem.
— Part III (Thursday): The Lower Elwha Klallam Tribe is counting on hatcheries to hasten the return of its subsistence fisheries.
River otters are among the Elwha’s top predators. That means they’re great indicators of the health of this ecosystem, and how conditions might improve once the dams come out. The problem is, right now no one really knows how many otters there are - either above or below the dams. But Sager-Fradkin hopes to solve that mystery using what are called jellies: clear, mucusy globs that otters defecate. Scientists think jellies, which are chock full of genetic material, help remove fish bones and scales from otters’ digestive tracts.
Sager-Fradkin has stored in a freezer about 50 jellies that she plans to send to a lab at the University of Montana to have genotyped. That way she’ll know roughly how many individual otters are frequenting the latrines, and she can estimate the local population from there.
She’s also set up infrared motion sensitive cameras at each of the traps to snap photos of the otters while they’re… ahem, going about their business. Right now her rough guess is that about two dozen otters live in the 45 miles of the Elwha River.
Once an otter is trapped Sager-Fradkin takes it to a veterinary clinic where a radio transmitter is implanted just below the belly button so she can track the animal once it’s released. One otter has been tagged so far and has already demonstrated that otters in the Elwha move above and below the dams on a regular basis.
Samples of whiskers, blood and toenails are also taken and those are sent to the Smithsonian Institute for Conservation Biology in Washington, D.C. There Peter Marra analyzes them for what are called “marine derived nutrients,” which otters get from eating salmon.
Basically, when a salmon comes into a river after being out at sea for a long time, most of the tissues that it’s accumulated have a very unique signature. When it dies, those signatures work their way into the water, the bugs, and on up the food chain. Otters contribute to that nutrient cycle in their small way by eating salmon and then frequenting the above-mentioned latrines on land.
At the Smithsonian’s lab, Marra can tell, from the chemical signatures that show up in an otter’s whiskers, whether it’s been eating salmon, which spend time at sea, or fish like rainbow trout, which spend their entire lives in freshwater.
When the Elwha River’s first dam was completed in 1913, it lacked fish ladders, as did the second dam, which was finished in 1927. He says that when the first dam went in on the Elwha 99 years ago, the whole nutrient makeup of this ecosystem changed because the salmon weren’t able to make their way into the upstream habitat and deliver those nutrients from the ocean to the trees. Tree core samples illustrate the health of the salmon run each year, based on how many nutrients show up in that year’s growth ring. Marra says that there should be a difference in the nutrient levels in tree rings sampled above the dams versus below, although samples from the Elwha have not yet been analyzed.
Otters will do their part in reconnecting the nutrient cycle from salmon to upland forests in the Elwha watershed. “As the fish come back,” Sager-Fradkin adds, “these nutrients aren’t just going to be left in the river. They’re going to be left in the forest as well and otters are going to play a big role in that picture.”
Sager-Fradkin stands at what might soon become one of the most interesting trapping sites for otters. It’s the Lower Elwha Klallam Fish Hatchery. For an otter, it’s kind of like McDonald’s. Otters have been known to get into hatcheries and chow down.
The trap here is empty but it is surrounded by droppings. That has Sager-Fradkin concerned for the future. As fish production here ramps up, otters might be tempted to take advantage of easy hatchery-raised prey, which could be a mistake that costs them their lives.
“I think there’s a balance that we need to find here,” she says. “Yeah, we want salmon back in the river but we also don’t want to have to get rid of all the predators to make that happen… They have a place. I’m a big believer in predators.”
So far, otters haven’t killed any fish at the new hatchery, which opened in May and will be releasing coho and steelhead salmon into the Elwha in the spring.
(River Otters in the Elwha, where the removal of two fish-blocking dams will make salmon a bigger part of these predators’ diet)
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