By Lee Anna Sherman
A river runs through Haley Ohms’ life. Actually, a whole bunch of rivers. So spending the summer hip-deep in fast-moving water will feel familiar to the Oregon State University graduate student — even if those cold, tumbling waters flow on the other side of the Pacific Rim. The fish will seem familiar, too. The Dolly Varden, which she’ll be studying in 10 woodland streams on the Japanese island of Hokkaido, is a cousin of steelhead and rainbow trout, the topic of her master’s thesis in the Department of Fish and Wildlife.
Sitting at her computer, she pulls up a photo on the screen. “This is the Dolly Varden,” she says, pointing to the underwater image of a moss-green fish speckled in red. “See how it’s spotted? It’s very similar to a trout.”
Fish is a subject she knows well. After all, you don’t sit atop a 30-foot tower in Alaska counting sockeye salmon at a rate of a million a month without getting really conversant with them. She was an undergraduate at the University of Alaska, Anchorage, when she took the tower-sitting job with the state Fish and Game Department, hopping a float plane from King Salmon to Bristol Bay and living in what she calls a “cabin-slash-shack” for two summers monitoring sockeye runs in the Egegik and Ugashik rivers.
But her kinship with fish started even earlier as a kid in Alaska. She was in her mid-teens when her dad, living out a lifelong dream, began taking summers off from his electrician’s job, bought a “bowpicker” boat, and took up gillnetting for Chinook and sockeye in the Copper River and for pinks and chums in Prince William Sound. She started crewing for him at 15.
At Oregon State, Ohms has spent two years learning the secrets of steelhead and trout in nine streams and rivers up and down the West Coast, places like Pudding Creek in California, Big Ratz Creek in Alaska, East Fork Trask River in Oregon and Secesh River in Idaho. Now she’s about to add Japan’s Sorachi River and its many tributaries to her growing list of study sites. She’ll be looking at the role of water temperature in the maturation rate of the Dolly Varden during her fellowship, jointly funded by the National Science Foundation and the Japan Society for the Promotion of Science. The Sorachi River, she explains, contains tributaries with two distinct thermal regimes: cold, groundwater-fed systems and systems fed by warmer surface water. That duality makes it a perfect place for an experiment, a readymade setting for studying the impact on fish of cold versus warmer habitat.
To get her data, she’ll be “electro-fishing” — sending a low-voltage electric pulse into the water, which stuns the animals and sends them floating to the surface. She’ll then net them, weigh and measure them and, finally, squeeze them, gently, to see if any eggs or sperm come out. “It sounds cheesy,” Ohms says, laughing. “But it’s the only nonlethal, low-tech way to tell if the fish are sexually mature.”
The timing of maturity in fish is critical to the survival of their offspring and, ultimately, of the species. “The males need to mature at the same time the females return to spawn,” says Ohms. “The females need to lay their eggs so they’ll hatch at the optimal time, not when the river’s frozen over or flooding. It’s a delicate balance.”
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