Researcher Spotlight: University of Washington’s Erika Sutherland is All About That (Smallmouth) Bass
By Emily Davis
If you live or work along a river in eastern Oregon, there’s a good chance that on a warm summer day you’ve cast a line into the water hoping to hook a smallmouth bass. These beautifully striped fish are plentiful in the John Day watershed, providing for a lucrative sport fishery in the lower reaches of the river where they were first stocked fifty years ago by Oregon Department of Fish and Wildlife. But their ubiquity and popularity belies a more unnerving reality: These nonnative fish are predatory, capable of consuming young salmon and steelhead. As climate change alters Western rivers, this warm-water fish is making its way into the upper reaches of the John Day—headwaters that currently serve as cold-water strongholds for wild spring Chinook salmon and summer steelhead. As bass move into critical spawning and rearing habitat for salmon in the Middle and North Forks of the John Day, each new generation of vulnerable juvenile salmonids is squarely in the path of hungry adult bass.
Luckily, someone is keeping an eye on the bass. For the last ten years, researchers from the University of Washington’s School of Aquatic and Fishery Sciences have been tracking the progress of bass as they make their way up the North and Middle Fork John Day Rivers. Recently, I caught up with Erika Sutherland, a UW PhD student studying smallmouth bass in the Middle Fork, to learn more about how bass could impact the Middle Fork’s native salmon and what we can expect to see in the future.
I joined Sutherland and her two field assistants on a brisk but sunny Saturday morning at a quiet riverside campground. After donning waders, we piled into her pickup truck—every crevice jammed with extra gear, snacks, or data sheets— and headed out to the first of three field sites along the river. Our mission: to capture young bass using a seine net, a large, unwieldy tangle of lines that is manipulated in the traditional, low-tech way: grab hold and sweep it through the water, then quickly lift up to trap any unwitting fish. After we captured the fish, Sutherland would weigh and measure them, then euthanize them to take back to the lab for further testing. Sutherland’s data collection goes much further than netting baby bass. Over the past three years, she has collected countless metrics to document all aspects of bass life from egg to adult—from snorkeling 80 miles of river to count bass to tagging 100 adult bass with radio tags and tracking them around the John Day watershed.
While we navigated County Road 20’s winding hairpin turns, I quizzed Erika about her research and her three summers of fieldwork on the Middle Fork. What follows is our conversation. [Editor’s note: Answers have been edited for length and clarity.]
ED: What made you decide to study bass here in the Middle Fork?
ES: My story about becoming an ecologist is a bit strange. I spent 12 years flying F/A-18s for the Navy prior to going to graduate school. Although I absolutely loved serving my country, my childhood dream has always been to be an ecologist. When deciding which field of ecology to pursue, I found that I was most drawn to rivers and streams, both for their beauty and their complexity. When I was accepted into University of Washington, I was fortunate enough to overlap with [then-PhD student, now Dr.] Dave Lawrence who was studying smallmouth bass in the North and Middle Forks of the John Day River. I went out in the field with him and absolutely fell in love with the river and the region. This place is absolutely magical – a true treasure. I’ve now been conducting my own research here since 2014.
ED: What is your favorite part about working in the MFJDR?
ES: My favorite part is a tie between the people and the magnificent landscape. Everyone has been so supportive, generous and fun. I feel like I have a second family out here, which has been so important considering I spend 5 months a year out here away from my home in Seattle. And the beauty of the landscape speaks for itself.
ED: Least favorite?
ES: Hmmmm, in 2014 it was the rattlesnakes. I swear every day I came face to face with one. I haven’t seen as many since then, so perhaps I’ll go with cow patties on the riverbanks. It’s a bit unpleasant to be pulling yourself along a bank of river, face in the water and put your hand right in the thick of it. There’s no mistaking that squish….
ED: Besides direct consumption of young salmon, how else might smallmouth bass end up being a bad neighbor for native Chinook and steelhead?
ES: I haven’t tested the effects of smallmouth bass on other fishes, but other studies have shown that smallmouth bass can compete for food and spawning grounds, crowding out other fish and indirectly affecting the reproductive success of salmon, trout and lamprey. Bass are top predators and they eat anything that fits in their mouths…..including a lot of insects, which are important for keeping water clear, providing food for other fishes and even providing food for the bird community that feed on hatching insects from the river.
ED: Didn’t salmon evolve with predators like northern pikeminnow? If they have native predators already, why is it that a nonnative predator poses such a disproportionate threat?
ES: As it turns out, salmon don’t display the same protective or defensive responses to smallmouth bass as they do to native predators that they co-evolved with such as the northern pikeminnow, making them more susceptible to predation by bass. [Editor’s note: Interested readers should check out Kuehne and Olden 2012 and Kuehne et al. 2012 for more information.]
ED: How far up the MFJDR have bass made it, as of this summer? Especially considering the warm temperatures and low flows of summer 2015, I imagine they made some progress.
ES: Smallmouth bass were resident up to the town of Galena in both 2015 and 2016. [Editor’s note: Galena is just 18 km (11 miles) downstream from the Oxbow Conservation Area, a major center of restoration activity.] There was a pretty good-sized population that were spawning at that stretch of river. This part of the river is still too cold for the bass to overwinter there, though, so the adults moved back downstream around September and it appears the young did not survive the winter. With warm summers and short winters, however, the young are likely to survive and adults are likely to continue to spread farther upstream.
ED: Are there any limitations to bass expanding their range all the way up the MFJDR, and if so, what do you think is holding them back?
ES: This is still a very open question, but right now it looks like a combination of warm water temperatures in July and August as well as low flows are important factors in defining the upstream edge of adult smallmouth bass distribution in the MFJDR. These factors also influence where bass can successfully reproduce. Juvenile survival depends mostly on how long the summer and winter seasons are. In short, if the upstream temperature and flow conditions change to suit bass, I predict they’ll expand into that region.
ED: Based on what you have learned in your research, can you make a prediction as to how the bass invasion will proceed up the MFJDR in the next 5, 10, 20, 40, etc. years?
ES: My former labmate, Dave Lawrence, modeled future bass invasion potential. He found that by 2040, bass would inhabit the entire Middle Fork and Chinook salmon would have only 4 kilometers [2.5] of suitable rearing habitat. By 2080, Chinook salmon are predicted to be completely excluded from the river. The good news is that simple restoration efforts such as providing shade to the river by planting streamside vegetation seem to highly influence these results, protecting the upper 31 kilometers [19 miles] of river from bass in the late summer. [Editor’s note: Those interested in Lawrence’s work should read his 2014 study here.]
ED: It seems like you’ve collected just about every possible data point about bass, excluding scuba diving under the ice in January to see where they overwinter. What’s your next step?
ES: My next step will be to use all the detailed information I have about the Middle and North Fork populations of bass to build a species distribution model that can predict the smallmouth bass invasion throughout the Columbia River Basin.
ED: What does all of this mean for restoration? If bass invasion is dependent on temperature, should we be making that our first priority so bass can’t continue to gain a foothold?
ES: This is obviously a tough question, and I don’t know much about river restoration. What I do know is that temperature appears to be a critical factor for keeping the Middle Fork a salmon stream, and our models show that shading the MFJDR could bring water temperatures down. I’ve seen other projects use temporary man-made shade structures to provide interim shade to streams while restoration continues and riparian plantings grow…seems like an interesting idea.
After half an hour of dodging cattle and deer alike on Middle Fork Road, Erika pulled the truck into a gravel pullout, and we all piled out, carting a jumble of buckets, nets, and various measuring instruments down to the edge of the Middle Fork. Baby bass like to spend their days in the pondweed at the edge of slower-flowing, deeper water, so we’d spend the day seining pools. We waded into the waist-deep water and Erika explained how to drag the seine net toward the shore as quickly as possible: “Just grab the net and sprint with it.” Sprint? Hmm…..I looked skeptically at the heavy seine net, doubting my ability to simultaneously maintain my balance in flowing water while hefting the net with enough agility to capture any bass, which are known for their quick swimming abilities. But I was here to help, so I gamely grabbed a corner of the net and crouched into position, awaiting the signal from Erika.
By day’s end, we were all soaking wet and freezing cold, with aching arms, but everyone was smiling—we’d netted dozens of bass and gotten the data we’d come for. As we drove back toward a warm meal and a fire at camp, we wondered aloud: What does the future hold for the Middle Fork’s native salmon and steelhead in the face of this invasion of the salmon-snatchers? Do restoration efforts provide hope for maintaining the Middle Fork as a salmon stronghold, and keeping the bass out? Time will tell—but thanks to Erika Sutherland’s dedicated research, we have more tools in our toolbox to help answer these questions.
Fritts, A. L., and T. N. Pearsons. 2004. Smallmouth bass predation on hatchery and wild salmonids in the Yakima River, Washington. Transactions of the American Fisheries Society 133:880-895.
Kuehne, L. M., and J. D. Olden. 2012. Prey naivety in the behavioural responses of juvenile Chinook salmon (Oncorhynchus tshawytscha) to an invasive predator. Freshwater Biology 57:1126-1137.
Kuehne, L. M., J. D. Olden, and. J. J. Duda. 2012. Costs of living for juvenile Chinook salmon (Oncorhynchus tshawytscha) in an increasingly warming and invaded world. Canadian Journal of Fisheries and Aquatic Sciences. 69:1621-1630.
Lassuy D. 1995. Introduced species as a factor in extinction and endangerment of native fish species. American Fisheries Society Symposium 15:391–396.
Lawrence, D.J., B. Stewart-Koster, J.D. Olden, A.S. Ruesch, C.E. Torgersen, J.J. Lawler, D.P. Butcher, and J.K. Crown. 2014. The interactive effects of climate change, riparian management, and a non-native predator on stream-rearing salmon. Ecological Applications.
Power, M. E. 1990. Effects of fish in river food webs. Science. 250:811-814.
Sanderson, B. L., K. A. Barnas, and A. M. W. Rub. 2009. Nonindigenous Species of the Pacific Northwest: An Overlooked Risk to Endangered Salmon? Bioscience 59:245-256.