A Critical Review of the Oregon Department of Fish and Wildlife’s 2022 Assessment of Naturally Produced Summer Steelhead in the Umpqua River Basin
Report Prepared by North Umpqua Coalition
Introduction
The North Umpqua Coalition appreciates the effort ODFW staff put into the 2022 Assessment of Naturally Produced Summer Steelhead in the Umpqua River Basin (hereafter referred to as the “Assessment”). We wholeheartedly agree that the Umpqua summer steelhead run is one of the most important fisheries in the state, which is why we are so focused on ensuring the population remains sufficiently abundant, diverse, and productive into the future.
Our fundamental concern rests on the Assessment’s conclusion:
“There is no indication that the hatchery summer steelhead program has negatively affected naturally produced summer steelhead, although there are more hatchery fish on natural spawning grounds than the management threshold allows.”
This statement is fundamentally contradictory. The proportion of hatchery origin fish spawning in the wild (pHOS) is quite literally the single-most common metric used to monitor and estimate hatchery effects, or a lack thereof, on wild salmonids. We realize that it is only a proxy, but measuring pHOS, rather than actual genetic effects, is analogous to taking a blood pressure measurement. The systolic and diastolic metrics can’t tell you about the exact imbalance between salt and water or the cumulative damage caused by hypertension, but it does warn you that your body is in a precarious position and such measurements alone – if beyond a reasonably accepted threshold of health – are sufficiently of concern to warrant changes in diet, lifestyle, and taking appropriate medication. Considering that a review of 266 peer-reviewed hatchery studies found that hatcheries almost universally have negative effects on salmonid traits and fitness (Araki and Schmid 2011) and ODFW’s own peer-reviewed publications indicate higher pHOS reduces the productivity of wild steelhead populations (Chilcote 2004; Chilcote et al. 2011), exceeding the management threshold is in and of itself, evidence of a negative hatchery effect.
In that vein, imagine if there was a single stream restoration project that could increase the wild population by even a few percent. Such an action would immediately rise to the top of any salmon recovery prioritization list. The reality is, short of dam removal, examples of measurable increases in abundance of salmonids due to habitat restoration are relatively rare.
However, one dial that can easily be turned is the release of hatchery fish. The North Umpqua is a unique and special population of wild summer steelhead, and each year, thousands of anglers travel to fish the famous river. With populations in decline and climate change impacts increasing at unexpected rates, now is the time to take bold action that will result in durable change. ODFW has taken bold action before with coho salmon. After years of investing in habitat restoration with almost no response, it took a large reduction in fisheries and hatcheries combined with an upswing in ocean conditions to get coho
salmon back on track (Falcy and Suring 2018; Jones et al. 2018). They’ve also shown muster in managing populations of wild coastal Chinook salmon. Managers now have the opportunity repeat those success stories here in one of the nation’s most iconic wild summer steelhead fisheries.
Evaluation of the Assessment
The North Umpqua Coalition does not find that the Assessment fully accounts for the effects of long-term hatchery releases on wild summer steelhead in several important ways. Below we highlight our specific criticisms and discuss the potential implications for wild summer steelhead in the North Umpqua.
1. Detecting hatchery effects on wild summer steelhead
Detecting the effects of annual variation in variables such as stream temperature, pHOS, smolt release size, etc. on subsequent adult returns is a data intensive task. There are several basic requirements necessary to identify these relationships, one of which is annual estimates of age class for returning adults Age classes of returning adults vary year-to-year and because steelhead display a wide array of life histories (e.g., Moore et al. 2014), a lack of age data makes it difficult to track environmental effects on the population. For example, juveniles from the 2017 adult returns could have smolted over three to four different years, but fish that migrated to sea prior to the 2020 summer would have avoided the Archie Fire. Fish that waited to smolt until 2021 would have experienced the fire. Simply put, each age class experiences its own unique set of conditions that impact survival, and without age class data, it is very difficult to estimate survival. While modeling age classes is a common practice, assuming constant proportions at age, as done in the Assessment, can prevent detection of significant results and lead to mischaracterizing relationships entirely (Zabel and Levin 2002).
Another fundamental challenge with evaluating hatchery and wild interactions is a lack of contrast. Contrast in this context refers to annual variability. From 1992-2014 there was relatively little variation in smolt releases and returns of hatchery adults. This could help explain, when combined with the simplistic age class assumptions, why the Assessment did not detect any hatchery effect on wild fish. However, it could also be that the worst effects occurred during the first generations that the hatchery was in operation (e.g., Seamons et al. 2012), and that analyses after that period cannot account for those types of “legacy” impacts
Fortunately, a stock assessment by McGie (1994) extends the period of record back to 19471985 and captures several years prior to the onset of the hatchery followed by several years after. And that data set has much greater annual variation (i.e., contrast) in wild and hatchery run sizes (Figure 1a) that provided us a better opportunity to evaluate the response of wild steelhead before and after the release of hatchery summer steelhead.
We used the data from McGie (1994) to graph the productivity of annual recruits per spawner in the report (1947-1985) in relation to the proportion of hatchery fish that crossed Winchester Dam in the same year (Figure 1a). However, McGie (1994) lumped his estimates of hatchery and wild spawners into one population, so the estimates of productivity do not just reflect the wild portion of the population,
but rather, for all fish spawning naturally in the North Umpqua upstream of Winchester Dam. Secondarily, we compared the relationship between annual estimates of productivity and the proportion of hatchery at Winchester Dam (Figure 1b).
Before interpreting the data, we first want to acknowledge the data set has limitations because McGie (1994) also used a constant proportion of age classes which means the recruits per spawner estimates may not be precise. Additionally, the hatchery proportion is only a relative metric because it does not account for fish that were removed above Winchester Dam. Owing to these assumptions, we only used the dashed replacement line in Figure 1a to separate years of high (above 1.0) and low (below 1.0) productivity, rather than to draw conclusions about the ability of the population to replace itself.
Regardless, Figure 1a indicates that wild summer steelhead productivity declined shortly after the onset of the hatchery program. As a result, the lowest productivity estimates for wild summer steelhead occurred when hatchery escapements were the highest. Figure 1b illustrates a general downward trend in wild productivity as hatchery escapements progressively increase.
There are two primary reasons for these observations. First, there could be direct effects on productivity via interbreeding between wild and hatchery fish. It is well documented that the offspring of naturally spawning hatchery fish survive poorly in the wild relative to wild fish, and when the wild and hatchery fish spawn together the survival of their offspring is reduced (Chilcote et al. 1986, Christie et al 2014) This would lead to reduced estimates of productivity because each spawner would be producing fewer recruits in the next generation. And indeed, the declines in productivity seem to start to increase about one generation of steelhead after the hatchery program was started.
Second, naturally spawning hatchery fish may also produce offspring that compete for food and space with wild juveniles. Accordingly, when the proportion of hatchery fish spawning naturally is high it could reduce the overall productivity by increasing the density of juvenile fish in the watershed. While we agree there is some spatial segregation of adults, juvenile steelhead can move long distances (Tattam et al. 2012). Given the high levels of naturally spawning hatchery steelhead, there is potential for numerous naturalized offspring to disperse and move throughout the North Umpqua, potentially greatly increasing the spatial extent of interactions between hatchery and wild steelhead in the North Umpqua. This form of competition and interaction is not addressed in the Assessment, and it challenges the assumption that spatial effects of hatchery fish are limited to where adults spawn.
Because we are looking back in time, we cannot state with certainty that the hatchery program led to reduced productivity of the population. However, considering the large body of peer-reviewed literature on the negative effects of hatchery fish (Araki and Schmid 2011) and that a peer-reviewed study has already concluded hatchery fish have contributed to reduced productivity of wild steelhead in the North Umpqua (Chilcote 2003), declines in wild productivity would not be a surprise.
Accordingly, it is important to clarify that while the Assessment’s models did not demonstrate a relationship between smolt releases and pHOS, that does not mean an effect has not occurred. It only means their analysis did not find an answer one way or the other. As we mentioned earlier, their data set did not cover the entire period of record and early stages of hatchery programs can result in rapid levels of hybridization between wild and hatchery steelhead (Seamons et al. 2012). This is exactly why the Assessment needed to cover the entire period of record for the hatchery program, because using only more recent data may miss important changes in productivity that occurred earlier.
Lastly, it is important to consider that ODFW only evaluated abundance and productivity. They did not evaluate genetic effects or changes in diversity and spatial structure, both of which are critical to population viability (McElhany et al. 2000). Reductions in diversity and spatial structure due to naturally spawning hatchery fish may be the most deleterious and difficult to rebuild because it can take many generations for genes to be re-expressed and habitats to be recolonized. For example, erosion of wild steelhead in Rock Creek and the Upper and Lower Mainstem Umpqua due to spawning and competition with hatchery steelhead essentially leaves only Steamboat Creek and Little River as places that are relatively free of hatchery influence. Steelhead will need every ounce of diversity and spatial structure they can muster if they are to persist through climate change and continue to provide the types of ecosystem services that ODFW values.
2. pHOS – Adjusting the proportion of hatchery fish to better reflect biological reality
The Assessment tries to rationalize a way to underestimate pHOS using a weighted average, relies on a small sample size of hatchery fish to broadly extrapolate spatial distribution for thousands of fish, and their methodology does not fully account for all potential hatchery spawners. There is no biological rationale for using weighted pHOS for the North Umpqua as presented in the Assessment. Due to the functional exclusion of hatchery fish from Steamboat Creek and the fact that it produces roughly half of the total abundance of wild summer steelhead, the 9-year recent average pHOS estimate of 34% is essentially already weighted In addition, although hatchery fish have lower fitness, they do produce some offspring and returning adults. Considering how many hatchery fish are spawning in nature and there are estimates of natural production for hatchery summer steelhead in other similar watersheds (e.g., Chilcote et al. 1986), OWDFW needs to begin accounting for those fish and their potential effects.
To account for the first problem, we calculated a coarse measure of pHOS for the entire population excluding fish that return to Steamboat Creek (Table 1). If we assume that half the returning wild steelhead consistently spawn outside of Steamboat, we can apportion the hatchery escapement to that half of the wild steelhead population outside of Steamboat Creek that do have opportunities to spawn with hatchery fish. This calculation results in an average pHOS of 50% (Table 1).
Second, we disagree with the strong reliance on a very small sample size in the telemetry study. This could have biased the results in different ways. For example, in the Assessment hatchery steelhead that were tagged early in the season (May-June) ended up in non-Rock Creek destinations more frequently than those tagged in July-October. Perhaps higher flows and cooler temperatures earlier in the season, combined with a longer wait until spawning, induce or allow for greater movement. Nor were the samples large enough to parse out sex-specific effects, such as the ability of males to move around the watershed and mate with multiple females. Even the most reasonable scientist would not put much faith in such a small sample size, and in this situation, extrapolating from 20 fish to predict the spawning destination of thousands of hatchery fish seems completely unreasonable.
Third, ODFW does not account for all potential pHOS sources. For example, smolts releases from Rock Creek likely contain some precocious hatchery males. Precocious hatchery males can disperse substantial distances from their release site and because they are released in the spring, they have ample opportunity to spawn with wild female steelhead (McMillan et al. 2007). Even a precocious male rate of only 3% for 15,000 smolts (assuming males are half of the total proposed 30k smolt release) would produce several hundred mature males (450 males in this instance) that would dramatically increase pHOS in Rock Creek and surrounding areas within their dispersal zone.
The Assessment doesn’t account for naturalized hatchery adults. To that end, we coarsely estimated the number of naturalized hatchery fish that returned each year using the limited available data on hand (see Appendix A for methods of calculation). Their adipose fin would be intact and consequently, naturalized hatchery fish would be outwardly indistinguishable from wild fish. While these hatchery offspring survived to adulthood it does not necessarily mean they are equal to wild fish. Rather, these fish are likely subject to the genetic “carryover effect” where their offspring continue to survive poorly relative to wild steelhead due to their hatchery ancestry (Araki 2009).
The results indicate the potential for a substantial number of naturalized hatchery adults in some years (Table 1). The additional fish increase pHOS from 1-5% per year, which may not seem substantial, but the true hatchery effect is likely greater because this also means that estimates of “wild” escapement are partly inflated by the presence of unmarked hatchery offspring. This can result in a masking effect, where chronic levels of naturalized hatchery spawners give the appearance of a more robust, wild population (Willmes et al. 2018). Last, the annual estimates of pHOS are not necessarily independent, because persistent hatchery contributions and carry over effects can increasingly add up and result in replacement of the original, wild population (Quiñones et al. 2015). In conclusion, it is clear ODFW has only accounted for one component of the hatchery problem (first generation hatchery adults spawning in nature), and as a result, they have underestimated the actual proportion of hatchery fish on the spawning grounds. Therefore, it is critical to begin genetically monitoring the population so that a detailed analysis can be conducted, and until then, we need to be conservative with pHOS estimates
3. Rock Creek is not a Wild Steelhead Sacrifice Zone and Steamboat Creek Can’t Do it Alone
The Assessment bases its conclusion that Rock Creek should be managed for a pHOS limit of 60% under the auspice that it has little value as a spawning or rearing tributary for wild summer steelhead. And, although the Assessment correctly values the relative refuge of Steamboat Creek, it undervalues the remainder of the population that exists in areas where there is a greater level of hatchery influence. Below we discuss why the former is an inexcusable simplification that is factually untrue and how the latter undermines the importance of spatial structure and diversity to the overall resilience of wild steelhead populations (McElhany et al. 2000).
First, Rock Creek is clearly an important tributary to wild steelhead because it has an annual estimated escapement of just over 200 spawners (ODFW 2022). It is likely some of those are naturalized hatchery offspring, but until that is known, they are considered part of the naturally spawning, unmarked population.
Second, steelhead throughout their range are well adapted to spawning in tributaries which provide no summer rearing habitat for their juveniles. This has been observed in populations from California (Boughton et al. 2009) up through the Olympic Peninsula in Washington (McMillan et al. 2013). The Rogue is a classic example where intermittent streams which begin to dry up as early as late May have been capable of supporting spawning populations of summer steelhead numbering in the thousands (Everest 1973) Hence, a lack of stream flow in summer is not a sufficient reason to conclude the habitat is unusable by steelhead.
Third, the creek is not necessarily too warm for steelhead, which are thermally resilient. The optimal temperature for development of steelhead embryo’s is generally considered to be between 8 and 12 C (Weber et al. 2016), and mortality begins increasing above 15 C (Weber et al. 2016) While only
one year of temperature data (2021) was readily available for Rock Creek, it shows that Rock Creek was well below 15C until the end of April. This provides ample time for hatching and emergence of steelhead fry prior to this period where mortality begins to significantly increase. In fact, Everest (1973) found that by late April to mid-May many steelhead fry had already reached lengths of nearly 50mm, indicating they had hatched at least a month prior Umpqua summer steelhead begin spawning in January which would provide ample time for their eggs to hatch prior to the onset of temperatures which would preclude their use of Rock Creek as a spawning tributary. This type of behavior and adaptation also improves diversity and the overall portfolio, allowing steelhead to use habitats that other species and life histories could not.
Fourth, during the record high temperatures of the 2021 “heat dome” Rock Creek reached temperatures of nearly 28° C in late June. While this is certainly above the optimum temperature for juvenile steelhead, there is ample evidence to suggest it is not lethal. For example, Sloat and Osterback (2013) found that juvenile steelhead were able to survive throughout the summer in Southern California when stream temperatures did not exceed 30°C (86°F), and importantly, thermal refugia were generally not present. Similarly, recent research by Armstrong (2021) and others demonstrates that habitats which are inhospitable for part of the year can be very important to the overall productivity of a population by providing opportunities for growth when other areas are too cold. Steelhead fry also have the highest temperature preference of any life stage, generally preferring temps of 19C (Kwain and McCauley 1978) indicating that even if Rock Creek does begin to reach lethal temperatures as summers get hotter, it may still provide productive spawning and rearing habitat long enough for fry to emerge and migrate to the North Umpqua as they have adapted to do in many other watersheds.
Fifth, Rock Creek is simply not a tributary that should be written off in exchange for a hatchery program. It is a large watershed capable of producing wild summer steelhead which contribute to the diversity and spatial structure of a healthy population. Thus, not only should it not be managed for a max of 60% pHOS, the goal should be to manage Rock Creek as an important component of the diversity and spatial structure of the North Umpqua Wild steelhead. This goal likely would require the elimination of the summer steelhead program, which is why we believe now is the right time to take a 10-year break on hatchery releases.
Lastly, if Rock Creek, Little River and other nearby tributaries which support spawning populations of summer steelhead warm to lethal levels or become intermittent in summer, it may become necessary for their juveniles to migrate to the mainstem to rear for the summer. If the mainstem becomes increasingly important for rearing, it would increase the potential for ecological interactions between hatchery and wild juveniles in the vicinity of Rock Creek hatchery. Deadline Falls acts as an upstream barrier to juvenile migration and since the North Umpqua exceeds preferred temperatures during the summer in the lower reaches, this essentially creates a habitat squeeze where residual hatchery and wild juvenile steelhead may be forced to compete for limited food and space or disperse to less optimal habitat.
4. Hatchery Return and Performance Metrics Not Worth the Risk to Wild Steelhead
Based on our review, the reduction to 30,000 hatchery smolts combined with the very poor eggto-smolt survival suggest the hatchery program is unlikely to achieve its production and conservation goals. We understand retention of wild summer steelhead has been closed in the Umpqua since 1990 so hatchery fish do provide an opportunity for harvest. However, we estimate the program would only produce roughly 300 hatchery fish for harvest using recent average rates (Table 3) and it may be
inconsistent given the poor survival of juveniles at the hatchery in some years. While we appreciate the effort to be more conservative, it greatly reduces the return on the hatchery investment because it reduces the number of fish that will be available to anglers.
Rock Creek Hatchery has experienced very poor juvenile survival in recent years ranging from 4% to 55% (Table 4). These low survival rates make it extremely challenging to run a consistent hatchery program. It is also important to note that the hatchery broodstock has been comprised of about 30% wild fish. In years where juvenile survival in the hatchery is very low these fish are essentially wasted as they contribute few if any offspring to the sport fishery and they do not contribute to the wild population in a positive way.
Our estimate of the number of hatchery fish which would spawn naturally at a release size of 30,000 smolts is still quite high at roughly 650 fish (table 3). This is particularly concerning given the overall underestimate of pHOS used in the Assessment and the low numbers of returning wild steelhead. If the downward trend for summer steelhead continues, it will be increasingly difficult to meet the pHOS goal of less than 10%.
Concluding remarks
For the above reasons The North Umpqua Coalition finds that the Assessment underestimates the impact the hatchery has had, and continues to have, on wild steelhead in the North Umpqua. Furthermore, a reduction of the smolt release to 30,000 is unlikely to meet the 10% management threshold for a significant portion of the North Umpqua. This threshold is designed to be an upper limit rather than a target and it is critical that we not exceed it given the tenuous status of wild steelhead in the North Umpqua. Wild North Umpqua steelhead dropped below critical abundance in 2021 and their future is uncertain. Pausing the hatchery program is necessary as an immediate step to provide wild steelhead the best chance to rebound and persist into the future.
In closing, we thank you for the opportunity to provide constructive feedback on the North Umpqua summer steelhead Assessment. While we may disagree on some of the issues, we also believe that we all hope for a strong future for these special fish, not only to ensure they perpetuate themselves, but also to leave something behind for the next generation. And that is why we are so committed to this place. It is one of the few remaining rivers and populations in the lower -48 that – if well managed – has the ability to persist and thrive through climate change.
Feel free to contact us with any questions or comments.
Sincerely,
Nick Chambers
John McMillan
David Moskowitz
MS Candidate – UW Science Director Executive Director
The Conservation
Angler
The Conservation Angler
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Figure 1. Panels display, a.) estimates of annual productivity (recruits per spawner, open circles) on the primary y-axis from 1947 to 1985 in relation to the proportion of the run comprised of hatchery fish (solid line) based on Winchester Dam counts on the secondary y-axis, and b.) relationship between recruits per spawner and the proportion of hatchery adult summer steelhead crossing Winchester Dam. The run size and escapement numbers used to calculate the recruits per spawner are taken directly from McGie 1994 and the proportion of hatchery spawners was aligned to spawning year in the recruits per spawner relationship.
Tables
Table 1. Unweighted pHOS is calculated by halving the wild steelhead count at Winchester Dam to simulate the wild population which spawns outside of Steamboat Creek, then dividing hatchery steelhead escapement by this proportion. The result is a coarse estimate of unweighted pHOS outside of Steamboat Creek.
Table 2. Estimates of the potential production of unmarked naturalized hatchery adult steelhead produced by hatchery fish that spawned in the wild. Methods for calculating these numbers are in Appendix A.
Table 3. predicted returns from a smolt release of 30,000 at Rock Creek using the average of 2014-2020. It is also important to note the 2021 escapement was estimated at 449 fish. This data was calculated with information extracted from the CMP hatchery and wild summaries.
Table 4. Egg to smolt survival calculated from 2020 CMP hatchery program summaries.
Appendix A
We estimated of the potential production of adipose intact feral hatchery fish born in the wild using hatchery escapements from 2014-2020 (ODFW 2021b). We used Chilcote (1986) to estimate that naturally spawning hatchery summer steelhead produced 28% as many smolts as wild steelhead. Estimates of wild smolt production for the North Umpqua of 30,000 to 61,000 were taken from McGie (1994) and multiplied by the pHOS in each year from 2014-2020 (ODFW 2021b) for an estimate of how many smolts could be produced at equal reproductive success. We then multiplied this number by .28 to estimate smolt production from naturally spawning hatchery fish. Smolt to adult return rate (SAR) was estimated for 2014-2020 by lagging adult hatchery run size estimates by two years after smolt releases from Rock Creek. We than multiplied the potential smolt production by the estimated SAR from each year to arrive at a range of estimated adults produced from the hatchery escapement.