by Carmen Macdonald
Well folks...if you want to dive into this one, I recommend a good stiff cocktail and a comfortable chair. I'll apologize up front for the length, but finding our way out of the woods and into a positive future takes some work. I thought about throwing some pictures of my kids or my dog in to break up the text, but that only makes it longer.
Here we go...
The debate over hatchery fish and their effect, or lack there of, on wild fish centers on a vast numbers of scientific studies that hypothesize numerous negative reactions within wild fish populations, caused by the presence of hatchery fish.
It's tremendously interesting, but none more interesting than how the research has taken root in conventional wisdom, even to the level of playing a role in court proceedings.
Most prominent within the scientific debate are studies of "relative reproductive success." In a nutshell, fish propagated in a hatchery and released into the wild do not reproduce at a rate equal to that of their wild counterparts.
At the core of that science are measurements of Recruits per Spawners. The science clearly shows that when hatchery fish are added to a system the ratio of natural (wild) recruits per the total number of spawners goes down.
For the sake of discussion, let's roll out a bunch of excerpts from the science right here, in broad daylight, thanks to an over-achieving contributor to ifish.net. Blouin 2009: "If anyone ever had any doubts about the genetic differences between hatchery and wild fish, the data are now pretty clear. The effect is so strong that it carries over into the first wild-born generation. Even if fish are born in the wild and survive to reproduce, those adults that had hatchery parents still produce substantially fewer surviving offspring than those with wild parents. That's pretty remarkable."
Blouin 2009: "The implication is that hatchery salmonids – many of which do survive to reproduce in the wild–could be gradually reducing the fitness of the wild populations with which they interbreed. Those hatchery fish provide one more hurdle to overcome in the goal of sustaining wild runs, along with problems caused by dams, loss or degradation of habitat, pollution, overfishing and other causes. Aside from weakening the wild gene pool, the release of captive-bred fish also raises the risk of introducing diseases and increasing competition for limited resources."
Buhle et al. 2009: "Our analyses highlight four critical factors influencing the productivity of these populations: (1) negative density-dependent effects of hatchery-origin spawners were ~5 times greater than those of wild spawners;
(2) the productivity of wild salmon decreased as releases of hatchery juveniles increased; (3) salmon production was positively related to an index of freshwater habitat quality; and (4) ocean conditions strongly affect productivity at
large spatial scales, potentially masking more localized drivers. These results suggest that hatchery programs' unintended negative effects on wild salmon populations, and their role in salmon recovery, should be considered in the context of other ecological drivers."
Christie et al. 2011: "These results demonstrate that a single generation in captivity can result in a substantial response to selection on traits that are beneficial in captivity but severely maladaptive in the wild. We also documented a tradeoff among the wild-born broodstock: Those with the greatest fitness in a captive environment
produced offspring that performed the worst in the wild."
Fleming and M.R. Gross 1993: "The divergence of hatchery fish in traits important for reproductive success has raised concerns. This study shows that hatchery coho salmon males are competitively inferior to wild fish, and attained only 62% of the breeding success of wild males. Hatchery females had more difficulty in spawning than wild fish and hatchery fish had only 82% of the breeding success of wild fish. These results indicate hatchery fish may pose an ecological and genetic threat to wild fish."
Ford, 2002: "Substantial phenotypic changes and fitness reductions can occur even if a large fraction of the captive broodstock is brought in from the wild every generation. This suggests that regularly bringing wild-origin broodstock into captive populations cannot be relied upon to eliminate the effects of inadvertent domestication selection
Ford 2010: "What is known from peer-reviewed scientific studies on the impact of hatchery salmonids on wild salmonids? Hatchery fish reproductive success is poor; there is a large scale negative correlation between the presence of hatchery fish and wild population performance; hatchery fish reproductive success is lower than for wild fish and this is true for both supplementation and production hatchery programs; there is evidence of both environmental and heritable effects; effects were detected for both release and proportion of hatchery spawners; negative correlations between hatchery influence and wild productivity are widespread; habitat or ocean conditions do not appear to explain the pattern; current science indicates that limiting natural spawning of hatchery fish is generally beneficial to wild populations; there is evidence that reducing hatchery production leads to increased wild production, and cumulative effects of hatchery could be a factor limiting recovery of some ESUs."
ISAB 2002. "We believe that available empirical evidence demonstrates a potential for deleterious interactions, both demographic and genetic, from allowing hatchery-origin salmon to spawn in the wild. Because it is virtually impossible to ‘undo' the genetic changes caused by allowing hatchery and wild salmon to interbreed, the ISAB advocates great care in permitting hatchery-origin adult salmon to spawn in the wild."
Jonsson et al. 1993: "Differences were evident for hatchery Atlantic salmon relative to wild salmon, with common genetic backgrounds, in breeding success after a single generation in the hatchery. Hatchery females averaged about 80% the breeding success of wild females. Hatchery males had significantly reduced breeding success, averaging about 65% of the success of wild males."
Knudsen et al. 2006. "Perhaps the most important conclusion of our study is that even a hatchery program designed to minimize differences between hatchery and wild fish did not produce fish that were identical to wild fish."
At face value, it's easy to leap to the conclusion that hatchery fish equal the eternal damnation of wild fish. The Native Fish Society appears to agree according to this quote from Oregonlive.com on January 20, 2014,
"There is no evidence that hatcheries have been effective in the recovery of wild populations,
" said Mike Moody, executive director of the Native Fish Society. "In fact, the evidence shows they foster a slow march toward hatchery-induced extinction."
Hatchery-induced extinction… good Lord this is serious stuff.
Apparently, Judge Ancel L. Haggerty agreed, stating, "There is very little evidence to suggest a hatchery can restore a wild population of fish,"
the judge wrote, "and the Sandy Hatchery is generally not intended to achieve any recovery goals. Rather, it is undisputed that hatchery operations can pose a host of risks to wild fish."
A "host of risks" says the judge. The Oregon Department of Fish and Wildlife says the same. They regularly assert that hatcheries pose "some risk"
to wild fish, though those risks remain "undefined."
So how can it be that in light of all of the above that the dialogue of damage by hatchery fish remains so completely unsatisfying? And how is it possible that this issue has been allowed to remain "undefined"
as it has been allowed to reduce the size and eliminate so many fisheries?
I believe the answer is ODFW's concept of "undefined." You see, for all the science that says hatchery fish are bad, virtually none of it translates to adult abundance levels.
And to go a step further, for a ton of management actions that have been taken to reduce and/or remove hatchery fish, there has been a total absence of all meaningful and measured results.
A mountain of papers has been produced, but nothing satisfying in the real world to the person that is the least bit inquisitive about what has been gained by reducing or eliminating hatchery fish. They allude to the potential for results, but the empirical evidence available to all of us says something quite different.
Many of us have invested our time into understanding the science and have then tried to apply it to the things we can witness all around us. The science is not lining up to what we can see.
Take it all in, lay the science on the table, and then consider…
IF HATCHERY FISH ARE SO BAD…IF HATCHERY FISH "FOSTER A SLOW MARCH TOWARDS HATCHERY-INDUCED EXTINCTION,"
then how are the following examples explained?
1. Why are we still talking about wild and native fish more than 100 years after the inception of hatchery programs? And yes, we still have pure wild fish. And where is a "hatchery induced extinction"?
2. How did the Sandy River begin with an average of 168 wild spring chinook in the 1960s, then emerge from 30 years of intensive hatchery management delivering and average of 2,187 adult wild spring chinook from 1999-2007? This seems completely counter to what would be expected.
3. How did the Upper Clackamas go from an average adult return of 506 adult spring chinook over the 21 year period from 1958-1978 to 2,000 wild adult spring chinoook, also after 20 years of intensive hatchery management? Again, the wild run did not go down, it went up!
4. How did the Nestucca emerge from 20 years of intensive hatchery winter steelhead management with as many as 10,000 wild winter steelhead in its population? Shouldn't it have been extinct, or at least near extinct?
5. Why has the removal of four hatchery populations, Spring Chinook, steelhead, Coho and trout, from the Upper Clackamas river delivered zero response from the wild winter steelhead population, though the science relating to the removal of the hatchery fish was considered a slam dunk?
6. How does the North Umpqua maintain stunning populations of both wild and hatchery winter steelhead over 60 years of hatchery influence? The wild steelhead population remains almost exactly unchanged now 60 years later.
7. Why have the Nehalem, Miami, Tillamook, Neskowin and Smith rivers, with wild fish spawning in complete isolation, not shown dramatic growth and deviation in the size of their wild populations in comparison to those rivers with hatchery fish? Their all recognized as having wild fish, but none emerge as outstanding with regard to the productivity of their fisheries.
8. Why do wild populations in the presence of hatchery fish trend exactly similarly to those wild populations under no influence of hatchery fish? Why is there apparently no deviation at all?
9. How were lowly hatchery silver salmon able to create one of the most singularly outstanding populations of wild silver salmon above Willamette Falls, an area with no historical population of wild silver salmon?
If you subscribe to the science of the "slow march towards a hatchery-induced extinction,"
all of the above examples would not exist immediately in front of us in the empirical world.
To point out directly the difference between what the science says and my points of contention above, the science focuses primarily on reproductive rates while my points focus on adult abundance. One might infer that the two go hand in hand, but that is not the case.
Confronted with the notable differences between the scientific papers and the empirical evidence of what is taking place around us, further investigation was necessary.
I've been afforded the opportunity to ask questions of top biologists. My basic question has been, what do these measurements of relative reproductive success mean?
The response was this: "Relative reproductive success is an attempt to measure relative reproductive ability in the absence of all other variables."
The next question is what we can infer from these studies when we make the leap to adult populations. The response is critical. And in short form, we cannot make the leap from relative reproductive success to adult populations at all. According to the scientist I spoke with, "if it were justifiable to do so, the authors of the studies would be doing it themselves.
" And they're not.
While the Mike Moody of the Native Fish Society can comment of a "slow march toward hatchery-induced extinction,"
not one credible scientist has put that in a paper, because the comment lacks all credibility.
I've been called a "hatchery apologist." I've been lumped into a group of sportsmen that, "…don't realize how bad they are screwing over wild fish."
I've been told that when a hatchery fish pairs and spawns with a wild fish that it nullifies the existence of that wild fish and essentially makes a withdrawal from the abundance of the wild population.
I've been told I don't care.
I'm here to tell you that all of those comments are a giant steaming pile of manure.
The scientist who I've spoken with clearly laid out to me that reproductive success cannot make the leap to adult populations because the number of assumptions that would have to go into a model to create the measurement would be so numerous that it would lack all credibility. In other words, it would be open to massive manipulation given inherent beliefs.
Given the juxtaposition of what science has delivered and what's available to anyone who wants to study the empirical evidence, it would seem that the priority of all concerned individuals, scientists or otherwise, would be to bridge the gap between relative reproductive success and adult populations. It would seem that all kinds of studies would be focusing on those places where hatchery fish have been removed in order to quantify what, if anything, has been gained. It would seem the Oregon Hatchery Research Center, constructed at a cost of $7.4 million and with an operating budget of $1.2 million per biennium in angler license fees would be all over this core question.
After all, the ESA is not judging populations on reproductive success, it's judging them by adult abundance. Perhaps we ought to put some focus on abundance.
The truth is, there has been a complete failure to address the issue by the Oregon Department of Fish and Wildlife and widely published hatchery scientists that include names like, Blouin, Kostow, Chilcote, Araki and others.
In this politically charged issue, one wise individual commented to me in regard to the lack of follow-though in the science, "When you have the answer you're looking for, you stop looking."
I do not want to believe that the leading names in hatchery science are engaged in what would amount to advocacy and social engineering, but when I consider examples like the Clackamas where hatchery programs have been removed and there's been zero initiative to measure results, I'm left to wonder.
One poster on a website said in regards to the Clackamas River, "I would think with the hatchery run out of the river for 15 years there has been research on what is hindering the native fish from growing in run size."
So would I. But that's not the case.
When we fail to measure results, yet continue to support continued actions that disconnect anglers from the resource, I wonder even harder.
Thankfully, a scientist has looked at the issue. Contracted by a group of irrigators, D. Brent Lister has no dog in the hatchery/wild debate, yet his recently published study is making significant waves in the region as the first that has looked at both productivity and adult population trends.
The study is a first of its kind.
The results of Lister's study run counter to what anglers are being led to believe by Fish and Wildlife Departments and preservation groups. It also is the only study that can provide explanation for the nine points I outlined above.
All study quotes that follow are from:
D. Brent Lister (2014) Natural Productivity in Steelhead Populations of Natural and Hatchery Origin: Assessing Hatchery Spawner Influence, Transactions of the American Fisheries Society, 143:1, 1-16, DOI:
And for those who are not aware, Transactions of the American Fisheries Society is one of the most difficult journals in North America to be published within. Crap work does not make the cut."ABSTRACT:
Natural productivity, the number of natural-origin adult recruits per parent, is an important parameter for assessing population status of steelhead Oncorhynchus mykiss (anadromous Rainbow Trout) and Pacific salmon Oncorhynchus spp. listed under the U.S. Endangered Species Act. Hatchery-origin adults comprise a majority of many salmon and steelhead spawning populations. In such cases, the utility of natural productivity estimates is affected by uncertain reproductive fitness of hatchery spawners and by possible ecological or genetic interactions among hatchery and natural fish. This study examined options for analyzing population census data to assess hatchery
spawner effects on natural productivity of mixed steelhead populations including spawners of hatchery and natural origin. It compared productivity in three mixed and reference (natural) population pairs, and estimated productivity as natural recruits per total spawners of natural and hatchery origin (Rnat/Stot) or as natural recruits per natural spawner (Rnat/Snat). Natural productivity estimated as Rnat/Stot reflected hatchery program scale, not productive capacity of natal streams. This analytical approach masked natural production dynamics in populations with a major hatchery spawner proportion, and was therefore of limited use for determining hatchery spawner influence. Productivity estimated as Rnat/Snat indicated similar productivity of reference and mixed populations, and an absence of hatchery spawner effect, in the case of (1) a large hatchery stray component, and (2) a hatchery supplementation program. In the third pairing, Rnat/Snat productivity of the mixed population significantly exceeded that of the reference population, suggesting natural spawner abundance is below carrying capacity. Hatchery spawners contributed to natural productivity in that case, but in the presence of reduced natural spawner density. These findings suggest that hatchery spawners are unlikely to affect natural production of a mixed steelhead population unless natural spawner abundance is below carrying capacity."
Lister's study differs from the rest of the reproductive success studies because most of them show in simple terms that the number of Recruits per total number of Spawners goes down when hatchery fish are added. Those studies do not appear to measure effects, if any, in the number of Recruits per Wild
Spawners within the mixed
In total, Lister's work concludes that when a wild population is at capacity, the addition of hatchery fish cannot grow the population. Capacity dictates what the population is capable of. It also concludes, that when the wild population is below stream capacity the hatchery fish, though less successful, actively contribute to adult spawner abundance. And finally, by using 25 years of comparative trend lines, Lister was unable to find any deviation in the abundance of adult summer steelhead between control (wild only) and variable (wild/hatchery) streams. The hatchery fish did not drag down the abundance of the wild fish.
Let's look at the nine points I mentions earlier to see if Lister's study helps explain them.
1. We still have wild, native fish today in spite of 100 years of hatchery production because in a competitive environment (one at capacity) wild fish win out over hatchery fish. I'm sure Darwin would agree, yet it seems everyday people advance arguments that the addition of hatchery fish leads to decline of the wild population…in essence saying that the less fit fish wins the competition for survival.
2. When the Sandy River was at 168 wild spring chinook, the river had unfilled capacity. The hatchery fish were able to contribute and fill this capacity, leading to many multiples of increases in the wild population of Sandy River Spring Chinook.
3. Clackamas Spring Chinook would offer a similar story as the Sandy. Unfilled capacity creates the opportunity for hatchery fish to be successful and contribute to the wild population.
4. On the Nestucca River, the inherent productivity of the wild fish remained intact throughout a 20-year period of intensive hatchery management.
5. The Upper Clackamas wild winter steelhead have shown zero positive results to the removal of hatchery fish because those populations were and are at capacity. This is extremely inconvenient to recovery plans that deliver overly ambitious targets for the river's productivity. Furthermore, it appears that instead of the wild steelhead productivity remaining even the same, it appears to be actually trending downward. This further degradation of productivity remains not only unexplained, it's apparently not even on ODFW's radar.
6. The North Umpqua, from the findings of Lister's paper, is a river at carrying capacity. The hatchery fish are surplus to the function of the wild population.
7. Again, one would identify the Nehalem, Miami, Neskowin and Smith Rivers as rivers that are at capacity. Lack of hatchery fish n these populations is making no difference to the trend lines of their adult populations.
8. Trend lines of rivers with mixed stocks of wild and hatchery fish and those with no hatchery fish track similarly because carrying capacity is dictating the success of the wild population, not hatchery spawner influence.
9. Going by Lister's conclusions, hatchery silver salmon were successful above Willamette Falls because there were no wild fish occupying the habitat. With unfilled capacity, the hatchery fish were able to be successful.
Lister's paper explains the empirical evidence of hatchery and wild fish interactions that surround all of us in the region. Not one other paper produced by the most prolific writers on the subject comes close to answering these questions. I do not recollect a single one that introduces the concept of river capacity as a limiting factor for the spawning success of hatchery fish.
Let's tease out a little of the detail. I've spoken with Lister a few times by phone at this point confirm what I thought I was reading was actually as he intended."Natural productivity has generally been estimated as natural recruits per total parent spawners of natural and hatchery origin (Rnat /Stot ), or as natural recruits per natural parent spawner (Rnat /Snat ). The former method implies an assumption that hatchery spawners contribute to natural production, while the latter method infers that they do not (McClure et al. 2003). In this paper, I determined the utility of information provided by each productivity estimation method, and employed the findings to assess the effects of hatchery programs on natural productivity of steelhead populations in the study."
If you look back through the posted science, it's clear that as you add hatchery fish to a population the number of recruits per the total number of spawners goes down. What that measurement does is apply an average across the total population as if all fish are equal. It does not tease out the productivity of the wild fish within the total mixed population to see if it is altered, or remains intact, with the addition of hatchery fish. According to Lister, the productivity of the wild population remains intact. "Absence of a statistically significant difference in Rnat /Snat productivity of a mixed and reference population pair was taken to indicate that the hatchery spawner component of the mixed population had no measurable effect on natural productivity of that population. Significantly higher Rnat /Snat productivity in the mixed population, relative to the reference population, suggested that hatchery spawners were contributing to natural productivity, or the hatchery program had created a positive density-dependent effect as a result of adult removals for broodstock or some other factor."
By comparative analysis, Lister was able to assess differences in the performance of control (wild only) and variable (wild/hatchery) populations. Where he saw a difference was in one creek where the wild fish were well below carrying capacity and the broodstock fish actively contributed to productivity.
Where previous science has been completely unsatisfying due to its inability to show what has or might happen to the adult population, Lister followed adult trend lines amongst his control and variable populations."Natural spawner abundance in mixed populations exhibited no significant trend in Deschutes (- 0.01/year, df = 29, P = 0.47) and Little Sheep (+ 0.04/year,
df = 16, P = 0.35) populations, which had the highest incidence of hatchery spawners (Table 1). The natural spawner abundance trend in the respective reference populations, Warm Springs (- 0.01/year) and Joseph (- 0.03/year), were also not statistically significant (P > 0.68). Significant positive trends were evident in natural adults returning to the Umatilla mixed population (+ 0.04/year, df = 22, P < 0.01) and Yakima
reference population (+ 0.07/year, df = 22, P < 0.001)."
In other words, the presence or absence of hatchery fish created no deviation in adult abundance between control and variable streams over a 25-year timeline.
So as these discussions continue, I'm often asked if I think the science brought to the table by preservation groups is jaded, wrong or influenced by advocacy for a particular outcome. I think the science is fine, however, I think it's being used completely inappropriately. Where people point to Blouin and say hatchery fish "foster a slow march toward hatchery-induced extinction,"
they're using the science completely inappropriately.
Lister concludes…"One study purpose was to assess the effects of including or excluding hatchery spawners when estimating natural productivity of mixed steelhead populations that comprise hatchery and natural spawners. For each mixed population, inclusion of hatchery and natural individuals in the parent population resulted in a markedly lower natural productivity estimate (Rnat /Stot ) than one generated by including only natural fish in the parent population (Rnat /Snat ). Differences in productivity estimated by Rnat /Stot and Rnat /Snat were positively related to hatchery spawner proportion in the mixed population."
This comment validates the work done previously, however, by virtue of comparing wild-only populations to hatchery/wild mixed populations, Lister adds, "These low Rnat /Stot productivities did not reflect natural spawner status in either population,"
It goes on…"In this study and an earlier analysis of Oregon steelhead (Chilcote 2003), mean productivity estimates that included hatchery adults in the parent population (Rnat /Stot ) tended to decline in rough proportion to hatchery spawner incidence in the population. These results suggest a situation exists where relatively unproductive hatchery steelhead spawners are commonly surplus to a natural population operating at or near carrying capacity."
Hatchery fish are "surplus." When a population is at capacity, they cannot add anything. Of equal importance though, is that they also do not destroy the more fit wild population, as so many would like to believe. "This suggests that, over a period of five generations, hatchery strays had no negative effect on reproductive success of the native population."
And, "Despite five generations of exposure to stray, multiple-generation hatchery spawners of local and nonlocal origin, there was no apparent effect on Deschutes natural steelhead productivity and status. A conservatively managed program to supplement natural production of Umatilla steelhead also had no measurable effect on productivity and status of that population. In contrast, natural productivity (Rnat /Snat ) of Little Sheep steelhead significantly exceeded that of the reference population, an apparent positive density dependent response to reduced natural spawner density, as well as a hatchery spawner contribution to natural production."
And finally, "The study findings indicated that hatchery steelhead spawners are unlikely to contribute measurably to the natural production of a mixed population unless natural spawner abundance is generally below carrying capacity."
Lister's study has the potential to turn conventional wisdom of wild/hatchery fish interactions on its head. Where we've been lead to believe that lower reproductive success of hatchery fish has a negative impact on the adult abundance of wild fish, his comparative analysis does not bear that out as true. The lower reproductive success of hatchery fish has actually maintained the integrity of wild fish populations in a mixed population.
Darwin would be happy. The fit survive and the rest are "surplus."
The closer you look at it, the more it makes sense. We hinder hatchery fish tremendously. A wild adult steelhead, born in the river, came from a successful wild spawning event. Nature will lead her to the area that produced a successful spawning event. Lister discussed some of this within the paper. "The nature of hatchery smolt-release practices, and their effect on smolt imprinting and adult homing (Kenaston et al. 2001), may constrain the ability of hatchery supplementation programs to achieve full utilization of river systems by hatchery spawners and their progeny. At Umatilla River, tracking adult steelhead movements by radiotelemetry indicated that most hatchery-origin adults select spawning areas near their smolt release sites on the river main stem and one tributary (Contor and Costi 2011). Apparent spawning locations of tracked natural origin adults were more widely distributed, primarily in tributary streams. In Birch Creek, a steelhead spawning tributary entering Umatilla River downstream from hatchery smolt release sites, weir counts revealed a hatchery spawner incidence that was just 6.8% of their incidence in the Umatilla steelhead population as a whole (B. Duke, ODFW, personal communication). In
Little Sheep Creek the juvenile progeny of natural steelhead spawners were recovered farther upstream than offspring of hatchery spawners, suggesting that natural spawners distributed more extensively upstream from the hatchery smolt release site (Moran and Waples 2004). Limited dispersal of hatchery steelhead adults to spawning areas upstream from smolt release sites has been observed in a number of studies (e.g., Mackey et al. 2001; Nelson et al. 2005). Selected spawning location has also been noted to affect reproductive success. Hatchery Chinook Salmon spawning in stream reaches used extensively by natural Chinook Salmon spawners had greater reproductive success
than hatchery Chinook Salmon spawning in a downstream reach near the hatchery smolt release site (Williamson et al. 2010)."
The paragraphs of Lister's paper are laden with quote-worthy text. It simply goes on and on with information that makes complete sense with what us common folk witness in the real world.
With as much enthusiasm as I read this paper, I sent it off to the Oregon Department of Fish and Wildlife. Though the paper had just been published, they were well aware of it and looking it over. In discussion, ODFW let me know they have serious reservations with regard to the study findings. I will be following up with the Department on their review of the study and am committed to reporting their comments back here.
I'm most concerned with finding the truth. Regardless of how the Department of Fish and Wildlife feels about this study in particular, I can only hope they're aggressively seeking answers to the questions that surround the events and empirical evidence that anglers see in the region.
Since the mid 1990's we've embarked on management that leans upon the removal of hatchery programs to derive benefits to wild populations. To date, those efforts have been wholly unsuccessful, and answers as to why remain non-existent. ODFW is unable to provide a single example where removal of hatchery fish has delivered any substantial benefit to wild fish. Instead, commentary includes the fact that if 100 biologists were lined up in a room, every single one of them would agree that hatchery fish pose "some risk"
to wild fish. That's fine, but it needs to be quantified.
All risks are not created equal and Lister's paper seems to deliver common sense answers to questions of hatchery and wild fish interactions. I'm hopeful that if Oregon refutes Lister's findings that they're able to offer answers that are both understandable and supported by what all of us are able to witness in the environments that surround us.