This work is an ongoing collaboration with Dr. Joe Sisneros at the University of Washington, Dr. Andrew Brown at the University of Colorado, and Mr. Tyler Jurasin, a tribal biologist with the Quinault Indian Nation. Ms. Chau Nyugen, a recent WSUV graduate, was also part of the project. This research was supported by a mini-grant from the Bloedel Hearing Research Center at the University of Washington.
Salmon are big business here in the Pacific northwest! Decades of over-fishing and habitat degradation have depleted native salmon and steelhead runs. Most of the salmon and steelhead in the rivers today originate in state- and federally-funded hatcheries, such as those run by the Washington Department of Fish and Wildlife.
Hatcheries grow salmon for a year, then release them into rivers where the fish live out the majority of their lives, migrating downstream to the Pacific ocean to mature, then back upstream to spawn. However, hatchery-reared fish often survive poorly once they are released into the wild. We wondered if sensory deficits, particularly of the lateral line, could account for part of this survival difference. The lateral line is system of hair cell-bearing organs on the head and body of the fish. Fishes use their lateral line to detect water flow, and the water flow in hatcheries is very different then in streams.
The picture at right is the head of a juvenile steelhead with lateral line organs labeled with the vital dye DASPEI (glowing orange dots). Note that the teeth are autofluorescent! We found that hatchery-reared juvenile steelhead had significantly fewer lateral line sensory organs that wild-origin fish (Brown et al. 2013). Hatchery fish also had more crystallized otoliths, a phenomenon correlated with reduced auditory sensitivity (Oxman et al. 2007). These findings suggest reduced sensory capabilities in hatchery steelhead. Our future work will examine lateral line development, physiology, and behavior in steelhead from hatchery vs. wild sources.