Celebrating Wild Abundance: Case Studies of Wild Fish Resilience

1. Coho in the Salmon River (North Oregon Coast)

Brief History of Hatchery Presence and Removal

The Salmon River Hatchery was built in 1975 and first released yearling Coho Salmon into the river in 1978. In 2005, it was determined by ODFW biologists that the hatchery was the principal threat to wild salmon and the Coho hatchery program ended in 2008, though Chinook are still produced at the Salmon River Hatchery. Within a few years of the Coho hatchery program ending, the number of natural spawners in the Salmon River were equal to or even greater than the number of hatchery Coho salmon that had been returning for the previous ~30 years. This was true even when conditions were generally unfavorable for salmon between 2009-2016.

At the same time the hatchery was installed, major restoration of the Salmon River estuary began. It is likely that the combination of ending the hatchery program and the restoration of the estuary environment has led to the remarkable recovery of wild Coho in the Salmon River.

Recent research indicates that there has been a substantial increase in Coho productivity and abundance of wild Coho since the end of Salmon River Coho hatchery program. In addition, rivers where hatchery Coho stocking had previously ended already had higher abundances and productivity in the same years where there were low returns of both hatchery and wild Coho in the Salmon River (Jones et al. 2018).

Size of Wild Population Pre-Hatchery

1975-76 estimate: 1,500, after ocean harvest of 70-85% (pre-harvest = 5,000-10,000)

Data from 2011 ODFW presentation slide deck

Size of Wild Population During Hatchery

1995-2008: mean = 323 (range = 15-1,801)

2009-2011: mean = 2067 (range = 810-3,868), transition period when some hatchery-raised fish were a portion of the spawners

Size of Wild Population Post-Hatchery

2012-2016: mean = 1603 (range = 362-4,279)

All data other than pre-hatchery estimate from Jones et al. 2018.

Supporting Materials

NFS Salmon River Watershed Page

Restoring the River Salmon: The Coho Return

Recovery of Wild Coho Salmon in Salmon River (Oregon)

Jones, K. K., Cornwell, T. J., Bottom, D. L., Stein, S., & Anlauf‐Dunn, K. J. (2018). Population viability improves following termination of Coho Salmon hatchery releases. North American Journal of Fisheries Management, 38(1), 39-55.

Nickelson, T. (2003). The influence of hatchery coho salmon (Oncorhynchus kisutch) on the productivity of wild coho salmon populations in Oregon coastal basins. Canadian Journal of Fisheries and Aquatic Sciences, 60(9), 1050-1056.

Theriault, V., Moyer, G. R., Jackson, L. S., Blouin, M. S., & Banks, M. A. (2011). Reduced reproductive success of hatchery coho salmon in the wild: insights into most likely mechanisms. Molecular Ecology, 20(9), 1860-1869.

2. Redband Rainbow Trout in the Metolius River (Central Oregon)

Contributed by River Steward Adam Bronstein

Brief History of Hatchery Presence and Removal

The Metolius River was one of the first trout rivers to be managed as a wild, native fishery in the state of Oregon. Stocking of hatchery rainbows began in the Metolius in 1938. Over twenty five years ago, wild fish advocates campaigned to rewild the Metolius and despite stiff local opposition, stocking of rainbow trout ceased in 1996. Today, redd counts have increased fifteen fold since counts began and the trend is continuing to move upwards. The Metolius is one of the best examples in the West that demonstrates wherever healthy habitat and cold water persists, mother nature can and should be left alone to work her magic. The Metolius's native fish are an incredible, abundant natural resource there for all of us to appreciate.

Size of Wild Population During Hatchery

141 redds were counted between the headwaters and Spring Creek in 1995-1996, the last year of the hatchery program.

Size of Wild Population Post-Hatchery

In 2019-2020, the most recent year for which redd counts are available, 2,037 redds were counted between the headwaters and Spring Creek.

Supporting Materials

Williams, R. N., Leary, R. F., & Currens, K. P. (1997). Localized genetic effects of a long-term hatchery stocking program on resident rainbow trout in the Metolius River, Oregon. North American Journal of Fisheries Management, 17(4), 1079-1093.

3. Redside Rainbow Trout in the McKenzie River

Contributed by River Steward David Thomas and NFS Member Arlen Thomason

The Problem:

The native “Redside” Rainbow Trout of the McKenzie River was an established destination fishery well before World War II. Post-war, ODFW began a program of outplanting out-of-basin hatchery origin fish in the river. In 1963, following their construction of several flood control dams on the river, the Army Corps of Engineers (Corps) built a new trout hatchery adjacent to Leaburg Dam (38.8 river miles above the confluence of the McKenzie River with the Willamette River). The rationale for the hatchery was to mitigate for the losses to the Willamette Basin fisheries caused by the dams. Over the years various stocks of Rainbow Trout were used in the hatchery’s outplanting program. Production was largely managed to meet demands from local anglers rather than any established limits regarding the impact of the hatchery stock on the native Redside population.

Though there had been no systematic population count, local anglers reported that they were encountering increasingly diminished numbers of Redsides, possibly due to interbreeding with or competition from hatchery trout. To partially assuage these concerns, the hatchery stock was converted to a mostly sterile (trisomy) strain. This likely answered any concern regarding gene-flow from hatchery rainbows reducing fitness of the wild spawning fish, but did not speak to possible competition between the native and hatchery stocks for resources (food and habitat). As in any situation where data are scarce, there was considerable disagreement among the fishing communities regarding what, if anything, should be done regarding the status of the Leaburg Hatchery trout program.

Citizen Science:

In 2009, ODFW announced that it would cease outplanting hatchery fish in a 5.1 mile section of the Lower McKenzie River. Seeing an opportunity to finally estimate the impact of hatchery stock, a group of conservation minded anglers, with cooperation from the local ODFW staff, designed a program to measure the effects of the hatchery stock removal on resident fish populations. Financing for study costs came from donations from local clubs and conservation organizations. From 2010 through 2013, 108 trained volunteer anglers floated and fished the study section using a “mark and recapture” model to estimate the numbers and physical distribution of species. The study involved 277 angling trips for 2,558.5 hours on the river.

Results:

After two years from the cessation of hatchery fish planting, the density of native Redside trout in the study section had more than doubled; at the end of the fourth year the increase was more than 300%. In parallel, the number of native spawning Cutthroat Trout also increased, but to a lesser degree. Interestingly, a parallel study by ODFW using electrofishing methodology came to the same result regarding the proportional changes in the fishery.

As a consequence of this study result, ODFW has continued to refrain from planting hatchery trout in this 5.1 mile section of the river, and the native Redside fishery there has recovered. However, the study results have not resulted in removal of all hatchery trout outplants from the rest of the river, although the study results suggest that it would be possible to quickly reestablish a flourishing native fishery throughout the McKenzie absent the hatchery program.

Sources

Lower McKenzie Wild Trout Population Study Website

Direct Link to Final Study Report

4. Coho Salmon in the Alsea River

Brief History of the Hatchery Program

The hatchery program began in 1952. The National Marine Fisheries Service (NMFS) determined that high levels of hatchery production was a major threat to coastal Coho, which were protected under ESA in 1994. As a consequence, the Fall Creek Coho hatchery program ended in 1998, with a dramatic clubbing event of returning hatchery fish. This angered many pro-hatchery folks and set the stage for a years-long battle over the closure of the hatchery program. Despite protests, ending the hatchery program was ultimately supported by scientific evidence and the last hatchery-produced Coho returned to Fall Creek in 1999.

Size of Wild Population Pre-Hatchery

Approximately 80,000.

Size of Wild Population During the Hatchery

Fewer than 300 in 1998 at the time of hatchery cessation.

Size of Wild Population Post-Hatchery

Approximate run size in 2021 was 12,000 but more than 25,000 were estimated in 2011 and 2014.

5. Bull Trout in the Elwha River

Submitted by Liz Perkin, NFS Northern Oregon Coordinator

Connection to the River

I was lucky enough to have had the opportunity to conduct research along several rivers in Olympic National Park, including the famed Elwha. At the time, in the summers of 2006 and 2007, we knew the Elwha dams were coming out, but the timeline for their removal was still uncertain. Scott Stolnack, my labmate whose research I was assisting with, and I backpacked up from the Whiskey Bend Trailhead and spent several nights camped near Humes Ranch. On our way up to the trailhead, we stopped by the Glines Canyon Dam overlook and imagined what it might look like once the reservoir drained and the river ran wild and free once more. While we collected data on the riparian habitat, Scott and I talked about how fish populations in the river might respond to dam removal. In the evenings, we were lulled to sleep by the clacking of cobble, as the river slowly worked its bed further and further downstream.

In 2017, my friend and I decided to run up Whiskey Bend Trail and again stopped by the Glines Canyon overlook, which now provides a view of the meandering Elwha and its recovering riparian zone. I was nearly moved to tears, as I thought of the newly opened, critical habitat that would once again be available to the anadromous fish of the Elwha. But while I was thinking primarily of Chinook and steelhead, Bull Trout were another species to greatly benefit from the dam removal. 

State of Bull Trout

Recent research following dam removal has shown that Bull Trout have quickly regained anadromy, and the age classes (e.g., 1 year old, 2 year old) are much larger than they were before the dams were removed. In addition, the number of Bull Trout observed in the Elwha has increased substantially since the dams were removed. Surveys from before dam removals found a total of only 117 Bull Trout in 2008 and a mere 86 fish in 2009. In 2018, this number had increased to 264 and in 2019, there were a total of 399 Bull Trout observed. 

The remarkable recovery and expansion of the population is at least partly attributed to their wild genetics. There has never been a Bull Trout hatchery program in the Elwha and so the fish there quickly adapted to their newly wild and free environment.

Sources

Brenkman, S. J., Peters, R. J., Tabor, R. A., Geffre, J. J., & Sutton, K. T. (2019). Rapid recolonization and life history responses of Bull Trout following dam removal in Washington's Elwha River. North American Journal of Fisheries Management, 39(3), 560-573.

Duda, J. J., Torgersen, C. E., Brenkman, S. J., Peters, R. J., Sutton, K. T., Connor, H. A., ... & Pess, G. R. (2021). Reconnecting the Elwha River: spatial patterns of fish response to dam removal. Frontiers in Ecology and Evolution, 9, 765488.

Dunagan, C. 2011. Bull trout in Elwha River given temporary refuge. Kitsap Sun. Last Accessed 27 July 2023.

Coho Salmon spawning on the Salmon River / Wikimedia

McKenzie River / Liz Perkin

Metolius River / Wikimedia

Bull Trout Density on the Elwha

Celebrating Wild Abundance