DR. PETER MOYLE & DR JASON BAUMSTEIGER: Assessing extinction in freshwater fishes
Drs. Moyle and Baumsteiger lay out a proposal for determining when to declare a species extinct
The extinction of a species is a major consideration in balancing water supply and environmental needs. It’s usually regarded as a “yes/no” state but its determination can be quite complicated. In this brown bag seminar, Dr. Peter Moyle and Dr. Jason Baumsteiger discuss general aspects of assessing extinction, focusing on native fishes of the San Francisco Estuary including the Delta smelt.
The seminar began with Dr. Jason Baumsteiger, a post-doctoral research fellow with the Watershed Science Center at UC Davis, outlining their proposal and guidelines for assessing extinction in California fishes. He was followed by Dr. Peter Moyle, UC Davis Distinguished Professor Emeritus of fish biology, who then gave examples of how the proposal would apply to California's native fishes.
“Many of you probably already know that extinction is a big problem, and we are current sixth mass extinction event; you might argue against that, but the science is basically there,” he said. “So what are we going to do about it? Are we just going to continue to wave to these species as they go by or are we going to step up and try and learn more about them?”
The International Union for Conservation of Nature (IUCN) list five categories for species: Least concern, Near threatened, Vulnerable, Endangered, and Critically endangered. He presented a graph of species under threat globally, noting that freshwater fish aren’t exactly doing very well. “Obviously, plants are doing worse, but there are a number of species that are obviously at risk of extinction. Almost all of them are going to fall into the endangered or critically endangered categories.”
There are really only two categories when it comes to actual extinction: extinction in the wild and extinct, said Dr. Baumsteiger. “In which case, their proposal is essentially you wait 50 years, and if you haven’t seen them, you call them extinct, which we think is a little bit vague and perhaps requires a little more definition,” he said. “So the other is if there is no reasonable doubt that the last individual has died. So what’s reasonable doubt? Well, if anyone watches any court shows, reasonable doubt gets a little iffy, so we’re going to try and define that a little better.”
Dr. Baumsteiger then made a clarification. “In the law, when it comes to extinction or defining extinction, basically it says a group of organisms must be defined as a distinct entity, and as most of you know, defining a distinct entity is also a bit iffy,” he said. “It might be a species, it might be a subspecies, it might be distinct population segment, an evolutionary significant unit, or a management unit. All of these things could technically go extinct, which makes it even more difficult to actually assess extinction. But for the sake of simplicity, we’re just going to call any of these groups a lineage. Rather than call something a species or subspecies or whatever, we’re just going to call them a lineage.”
He then posited a series of thought-provoking questions: “In your mind, is extinction essentially presence-absence? They are here one day, they are gone the next – Is that how you see extinction? Many of you, maybe the answer is yes. What if a single individual still exists – is that lineage extinct? What if it’s completely reliant on humans? Meaning it can’t exist on its own; it’s completely reliant on us. Is it extinct? What if it’s absent from its native range; there is literally no more out in its native range. Are they extinct? What if it has no habitat at all? What if it lives in a spring and that spring is gone. You’ve got it over here in some pool. Is it still extinct? Is it still the same species? What if it’s been genetically modified? Or as some people have been proposing, what if you hybridized it with something else. To save this lineage, what if you hybridized it with its next closest relative. Has that actually lineage gone extinct?”
Maybe presence-absence isn’t the easiest thing to define, he pointed out. “What happens when something gets really, really small and you have just a few number of individuals. It’s very cryptic. For example, in fishes, it’s really hard to find them sometimes, so do you just say. I can’t see them, I’ve been out 20 times. Is that enough? Are they extinct? When do we start, how far do we go? This is what we’re going to try and get into.”
Dr. Baumsteiger said the he and Dr. Moyle believe that extinction is more of a process that we need to work through, and they are going to set out some guidelines for that process. But first, he had to discuss some difficult things.
“Humans impact virtually every aspect of the planet,” he said. “There is virtually no species lineage, anything that can exist that doesn’t have some impact by us on it in some way or another, so we can’t really just discount all of those and say that’s a natural system.”
Human impacts are unavoidable, so we need to differentiate between indirect and direct effects, he said. Indirect effects are things that affect the whole system and natural selection is primary driver; direct effects are human caused, lineage specific and artificial selection is the primary driver. He explained that natural alternatives can be things such as building a dam, for example, and that is still an indirect effect. “You could have a landslide and that could create a dam, so there are these kinds of things that exist in nature. It’s not just us; it’s kind of an indirect effect. These indirect effects apply to whole group, so every fish in a particular habitat is affected by a dam, not just one particular species or lineage, whereas direct effects are lineage specific. We’re acting specifically on that lineage that we’re interested in, and only humans really cause those kinds of changes, and usually in this case, artificial selection is the primary driver.”
Differentiating between indirect and direct effects is a key component of assessing and preventing extinction, he said.
He then presented a chart with some examples of indirect and direct effects to illustrate what you expect to find when you have natural selection versus what you expect to find when you have artificial selection.
“When you look at artificial selection, you’re talking about specific traits,” he said. “You’re talking about success and fecundity as being maximized; you’re not allowing things to just vary, you are specifically targeting things; you’re doing things that are in a way unnatural, and that is why it is artificial selection. You are artificially mating, you are genetically modifying, you are doing a lot of things that would never happen in a natural system. You’re eliminating things like pre-zygotic barriers, predation, biological interactions, parasitism; you’re giving them antibiotics, let’s say you’re in a hatchery; you’re doing a lot of things that would never exist otherwise, so would that make them extinct?”
Dr. Baumsteiger then gave another example. “Obviously pugs are descendants of wolves. Through artificial breeding over a number of years, we domesticated and created a pug. Are these the same? So if I was to say, I believe we need to put the pugs back into Montana because that’s what’s missing, shouldn’t we do that? Aren’t they the same? Even if you wanted to go a step further, aren’t their genomes essentially the same? There’s very, very few actual genetic differences between pugs and wolves. But are they the same thing?”
“Uh oh, now it’s more complex,” he said.
Dr. Baumsteiger then laid out their proposal:
If fish are still living in their natural environment under natural selective pressures, we argue those fish fall under the vulnerable/endangered category system.
Because all impacts, no matter how severe, are indirect effects.
If direct methods (lineage-specific) are applied, these fish(es) are now conservation-reliant, completely dependent on humans for their survival/existence. This is a deviation from anything that could happen in nature (hence artificial) and therefore the natural form has been lost. A level of extinction has now been reached.
These fish(es) would still receive the same treatment and management efforts as before, only now they would be recognized as altered. They are not the same as the original wild fish but some version is still better than none at all.
Dr. Baumsteiger then further explained: “What we propose is that the endangered species, critically endangered, threatened – we believe that any lineage that falls in those categories; it’s still in its natural environment, under natural selective pressures. In which case, no matter how many there are in that particular area, whatever you feel that population range seems to be, those are still indirect effects and those fall into that category in the system.”
“But if you start applying lineage specific effects where you’re essentially applying artificial selection on to a lineage, we believe that this has reached a level of extinction,” he continued. “Because it’s no longer the same natural organism in its natural environment. Is that to say that we don’t protect it or anything like that? We’re not saying that at all. It still gets its protection because something is better than nothing. 80% is still better than 0, but we still need to recognize that trying to trot out pugs and say that they are wolves is not the same thing, and a lot of times we’re getting caught doing that.”
“What made a wolf a wolf is not encapsulated in a pug, no matter how much we try,” he said. “But that still means it’s better to start with that, because maybe pugs, I don’t know, give them 100 years, will they look more like wolves? Do you think evolution would act like that? But isn’t that essentially what we’re doing with a lot of our fish species?”
Dr. Baumsteiger said they will propose six novel categories and a series of guidelines for the process of determining extinction. “Our primary goal is just to provide and easy step by step process to assess extinction,” he said. “Secondarily, we want to highlight the fact that applying indirect effects and trying to alleviate indirect effects should happen first before we ever consider applying direct effects. We should try very, very hard to work through all the things that are causing extinction that are indirect before we start applying direct, so that we do what everyone wants to do which is avoid extinction.”
Category 1: Mitigated extinction. Conservation-reliant lineages that depend on continuous human action to maintain viable populations; Threats cannot be eliminated, only managed. This category also includes intentional hybridization or genetic modification.
He acknowledged this first category is a little bit controversial. “Once something becomes conservation reliant, meaning it’s basically depending on us for its existence, we believe it’s reached the first category which we’re calling mitigated extinction. Essentially, that lineage was going to drop out and we went in and saved it, but in order to do so, we had to apply artificial selection and maybe have to continue to apply it; we mitigated on its behalf, otherwise it doesn’t exist at all, so we’ve reached out first category. This all includes if we have to intentionally hybridize or essentially modified something. It’s not the same natural lineage in its natural environment under natural selective pressures.”
Category 2: Regional extinction. Lineage is extinct in a geographically distinct part of its native range although may be abundant elsewhere.
“This is more of a category for simplicity of bookkeeping. For example, bull trout used to extend into California, but they no longer do so. So you would say they are regionally extinct here in California, but are bull trout extinct in North America? No.”
Category 3: Native range extinction. Lineage is no longer present in its native range but has been introduced successfully outside of its natural range.
Category 4: Wild extinction. The lineage is no longer present in any natural environment but maintained as captive populations in hatcheries or artificial habitats.
Dr. Baumsteiger gave the black rhino as an example. “There are no native organisms in their range doing anything they are supposed to. They are handfed in a zoo, they are bred specifically. Would they choose the partners that they are bred with? No, so we’re eliminating all of those facts.”
Category 5: Visual extinction. No verified observation anywhere despite significant efforts. A waiting period based on generation time is observed.
“Now we don’t see any anywhere. Do we just call them extinct? No, we don’t think that’s really what you need to do. You need to have a waiting period.”
Dr. Baumsteiger said that determining waiting periods in years doesn’t really work, due to the wide variation in lives of organisms; such as pupfish versus sturgeons. “So we propose to do it by generation time. So if you have an organism that has a 0 to 5 year generation time, you would wait approximately 10 generations. If it has greater than 5 year generation time, then you would wait five generations. This allows for a conservative wait time but not such an exhaustive time as you’re waiting 50 or 100 years or something like that. It doesn’t really allow for good management practice in our opinion.”
Category 6: Global extinction. No verified observation anywhere, even after waiting period.
“What we hope is these simple categories with these designations make it easy for you to categorize which one and which level they have reached,” he said.
He then presented a flowchart for the proposed extinction process. “This is basically our diagram of how you would work yourself through which level your lineage has reached in terms of its extinction category,” he explained. “You start at the top, you ask yourself a series of questions, and work through a simple flow diagram. There’s a diversion that I want you to see right there at the beginning, where it asks whether or not you are going to apply direct effects or continue to apply indirect effects. If you’re going to apply indirect effects which means you’re not going to go in and specifically artificially select on that lineage, then you stay in the left hand category. It’s just really low numbers, they are dropping out. But if you start applying things and they still continue to drop out, then you would move into the category on the right.”
“Finally, you see it through the checkpoints,” he continued. “We believe there should be an assessment committee of a group of biologists who should get together and assess these things yearly and be able to categorize as these different lineages work themselves through these various categories that we’ve proposed.”
He then briefly reviewed the four checkpoints:
Checkpoint #1 –Initial information brought to committee. Committee makes recommendations concerning the underlying cause of decline/extinction, listing as vulnerable/endangered and potential to alleviate any indirect effects through system or habitat restoration.
Checkpoint #2 – Assessment of extinction –have all indirect methods been exhausted? Are direct methods the only way to continue the lineage? Are funds/management in place for program of conservation-reliance? Extinction categories assigned.
Dr. Baumsteiger said the issue of funding is important. “Once it becomes conservation-reliant, you are paying for it for all of existence,” he pointed out. “It’s completely dependent upon you forever. That’s a big commitment, so you should probably have something in mind if you’re going to go down that particular road.”
Checkpoint #3 – Reevaluation of extinction categories –should happen yearly for each species. If wild extinction status has been reached, monitoring programs should indicate no individuals are found anywhere. Intensive targeted sampling efforts should be employed to look for small populations. Set waiting period (based on generations) if no individuals found (visual extinction).
Checkpoint #4 – Final information collected and global extinction confirmed.
“This is a simplified process,” he said. “Obviously there’s much more that goes into this. We wanted to just give a simple way to assess extinction.”
So what is the conservation relevance of all of this? “Lineage specific efforts that we do are costly, often permanent, and they alter the evolution trajectory of the organism that we’re interested in,” he said. “Is that really the plan? Obviously in certain situations yes, we have to do that, but I think we need to recognize those situations where we can still put a natural organism in its natural habitat under natural selective pressures. If we can maintain that, then we really have saved the organism that we’re interested in.”
Dr. Baumsteiger said the focus should be on the indirect effects first. “Alleviate the indirect effects, because that’s a one-time effort, that’s not based on a single lineage, but protecting multiple lineages,” he said. “For those of you who are familiar with the Endangered Species Act, every single lineage is protected and everything has to be done for every single lineage individually once you reach that category, so if you have a system that’s in big trouble, instead of saving the system, you have to then fund every single lineage that’s becoming extinct independently, and that can get really costly.”
He said the guidelines are meant to bring to light the problem of artificial selection and how it changes things. “It might be absolutely necessary to avoid extinction, because we’re talking about the end of the end of things, so we’re not trying to condemn direct efforts, we’re just trying to minimize them as a last-ditch effort.”
Dr. Peter Moyle next gave some specific examples to show how this applies to California fish.
“Unfortunately, we’ve have experience with extinction in California and we are at the stage where we’re seeing a high percentage of our fishes with a trajectory towards extinction,” Dr. Moyle said. “You can believe me or not on these things, but the fact is that we have 30 species of fish that are currently listed by the state and federal endangered species acts, so it’s not just me imagining that there large numbers of fish out there that are not doing very well.”
Dr. Moyle then went through each of the proposed categories of extinction and discussed them in relation to California fish.
“The classic example of a mitigated extinction is winter-run Chinook salmon; it is a conservation-reliant species and it will go extinct without human help,” he said. “Their habitat is just below Shasta Dam (which is not their natural habitat), and they are totally reliant on spawning gravels that we provide, they are reliant on flows that come from the dams, and in really severe times like we’ve had the last few years with the mismanagement of the water and so forth, they’re totally reliant on a hatchery as well. So that’s a classic example of a species that would not exist without continuous human input, and most of the conservation proposals for this continue that process.”
Regional extinctions are species that are still extant, but are extirpated from part of their range. “The bull trout is an example; 1975 is the last time any of them were caught in the McCloud River. It’s a good example of regional extinction but it took a long time for us to figure out that they really were gone.”
On the Colorado River, the bonytail and the Colorado pike minnow are both gone from the Colorado River in California. “They are still barely hanging on the upper parts of the Colorado River basin, the Yampa River and places like that, but they are extirpated from California,” said Dr. Moyle. “We no longer have them as part of the California fish fauna.”
The Sacramento perch is an example of the species that is extinct in its native range. “You can go to Crowley Lake and catch them in large numbers, but they are absent in their native range which is the Central Valley in California, except in ponds where I have and others have planted them, but those populations are very ephemeral. This is a species which you can regard them of being essentially secure because they are outside of their native range, but the fact is those populations outside their native range are not protected and they are blinking out one at a time.”
Extinction in the wild is a species that’s entirely maintained by captive populations. “An interesting example of this is the Mojave tule chub, which is gone from the Mojave River, and is only present in a bunch of ponds,” he said. “A dietary study was few years ago and a high component of its diet was bread crumbs, which gives you an idea of how conservation-reliant they are.”
Visually extinct species are those that are apparently extinct but we don’t really know for sure, so we’re still looking for them. “I can’t find any good examples in California and maybe that’s a good thing, but the Delta smelt may be approaching that category, though,” Dr. Moyle said. “The IUCN comment is, a species is extinct when there’s no reasonable doubt the last individual has died, and that just leaves you with the problem of defining reasonable.”
Other California species that have gone extinct are the Clear Lake splittail; they used to be hugely abundant in the lake but the last ones were caught in the early 1970s. The last thicktail chubs were caught in the 1950s; they were one of the most abundant fish in California and Central California and an important food for the Indians, he said.
Dr. Moyle then reviewed the proposal for how to determine if a species is extinct. He pointed out that currently, there aren’t that many that are in the condition where they might disappear in the next few years, but with climate change and sea levels rising, this could be a very real problem in the future.
“First, your recovery measures have to fail, both ordinary and extraordinary,” he said. “For example, I think we’re at a point right now where we should be experimenting with these captive populations of smelt that we have. This is before the smelt disappears in the wild, assuming it does, we have this captive population that could be used for out planting in places. This is a photograph of our pens for raising salmon in the Yolo Bypass. I can certainly imagine having smelt reared in those pens for awhile, especially since we’ve discovered in recent years that the toe drain in the bypass and some of the permanent freshwaters in the North Delta actually support year round populations of smelt. So here’s an opportunity, we should be experimenting with these fish while we still have a chance. That is an example of the extraordinary measures that we need to be taking.”
“You have to determine their absence from routine surveys,” he said. “The smelt now is just about disappearing; it’s at the levels of detectability right now. The latest surveys for the juvenile fish, we had indices of 0.0. The next step in all of this is to conduct all these intensive surveys in all the likely and unlikely places. We’re already doing that to a certain extent with Delta smelt … maybe we should be looking in places like San Luis Reservoir, and trying to see if there are other places where these smelt might exist or could exist.”
“If you don’t find any under those circumstances, you go back to your routine surveys for a fixed number of years, based on generation time,” Dr. Moyle said. “In the case of Delta smelt, we would say you would look for them for another ten to twenty years before you declare them extinct, but you have to go back to your routine surveys because they would tell you whether or not they are present.”
For the final steps, a group is assembled that will determine the likelihood the species is still extant or extinct. “You present the findings to a multi-agency committee of all of the diverse people who might be interested in this; then the committee would make a recommendation to the Director of the Department of Fish and Wildlife, or the Fish and Game Commission. Then the highest politician in California should declare it extinct. You want somebody to take responsibility for this, and that’s why we say the announcement should be made by the Governor, or if it’s a federal case, by the president, no less.”
“Keep in mind, we’re facing climate change as an increasing probability,” Dr. Moyle reminded. “When you add climate change as a factor in predicting the likely extinction of species in California, you get up to 82% by the turn of the century.”
“So in summary, extinction is likely to become common in the future, and certainly the trends of all kinds of organisms that indicate this,” he said. “It comes in many flavors, it’s not easy to define exactly what we mean by extinction and we need to make sure we do know what we mean by extinction. Legal means to exist to delist extinct species, but we need good legal means to do that. The existing means are not very good. And formal processes are also needed for determination.”
At this point, the floor was then opened up for discussion.
Comment: “I think that the example of the pugs and the wolves, it’s a good example conceptually, but I think it’s a little misleading … in regards to the smelt, I’m involved in the genetic management of the Delta smelt. Yes, artificial selection is undoubtedly a problem, and we don’t want to be reliant on a hatchery for the Delta smelt to survive. However, that said, we are bringing wild fish into the population every single year, and so doing the best that we can under the circumstances with the limitations to maintain a population that we hope can be reintroduced into the Delta and survive.”
“That’s what happens when you can no longer collect enough from the wild to maintain those populations, and it’s already happening,” responded Dr. Moyle. “We’re almost at the point where Delta smelt are becoming pretty much a domesticated fish in the sense that they are entirely dependent on culture. It’s absolutely one of the best and most sophisticated culture operations that’s ever been done for a fish, so it’s pretty remarkable. But you still have that problem; any time you keep an animal in captivity for any kind of a length of time, it’s undergoing artificial selection and you almost can’t help it. That’s why we need to be .. now, which .. we need to be experimenting now with those fish, trying to see how can we reintroduce them into the wild, if it’s truly a backup population, or is it just going to be a fish we have in aquaria for people to look at and say, here’s an extinct species. But we need to experiment with them.”
Commenter: “I totally agree on that count.”
Next question: “Seems like people oftentimes don’t go into doing these direct things, such as a conservation hatchery for example or supplementing spawning substrate, thinking that it’s going to go on forever, so can you comment on the potential for these actions to be temporary? Then would you list something extinct under one of those six categories and potentially unextinct it later? I’m looking at how there can be some policy problems here … “
“That was the hardest thing,” said Dr. Baumsteiger. “Is it an opinion thing? Can Peter and I stand up here and say this is what you should do, this is what you shouldn’t do in these situations? That was kind of the hardest point. You can restore something, but you can never make it what it once was. It will become something new, because you’ve messed with it. Say you take it in and you artificial select for 20 years, 50 years. Does that change it? 5 years. Does that change it? That’s a hard thing. In my opinion, it was that it never gets past mitigated extinction. You always have to recognize that at one point, we had to come in on its behalf and save it or it wouldn’t exist at all. As soon as you had to apply direct effects to maintain it from going globally extinct, I think that it has reached that category that it will never go back to what it once was.”
“That’s why we suggest that the committee exists,” continued Dr. Baumsteiger. “A group of biologists with different interests so that no one interest is represented comes together each time and assesses where these things are and what level of extinction they have reached, and say ‘no, we think that this is still essentially the same species in its natural habitat, and that we had to do this very small effect, we don’t think that this really matters,’ and then have to write that up and justify it to the rest of us as to why they made that decision. But I don’t think any one person should do that, in the way that Peter and I can’t sit up here and say in every single case, you should do this or you should do that, I think that’s too subjective … “
Question: “For winter-run Chinook salmon, Peter used the term mitigated extinction. I think probably that’s a good concept for scientists to use, except but in reality, maybe it’s hard for some .. to use the term ‘extinction’. What do you think?”
“The question really is all about using the word extinction when you still have the fish in front of you,” responded Dr. Moyle. “We still have fish we are calling winter-run Chinook salmon out there, how can you give them some category of extinction. We started doing that in part to be provocative, but the reality is what do you mean by extinction? The winter run is not out in the natural population much anymore, even though it is migrating out to sea, it’s not really doing much in the system. It’s certainly not playing a role in the ecosystem to any great extent; it’s entirely dependent on our maintaining its population. If we defunded the winter-run Chinook salmon program, the hatchery, the gravel replacement, even the water releases from Shasta Dam, that species would be gone in a couple of generations. If a species is extinct except for the grace of humans, we’re allowing its existence to continue, and I think part of our idea is just let’s be honest about it and say that’s what’s really going on here. And I hope you don’t all agree with that.”
“What is it that defines a lineage as it is?,” added Dr. Baumsteiger. “Is it just it’s physical presence? It’s all the things that make it up, it’s the pre-zygotic barriers, the sexual selection, which ones mate with which ones, where do they live, why do they live there, how do they fit into the ecosystem – if we are artificially selecting, we’re taking those things that would naturally be occurring in that system and removing them. For example, if we put a fish in a hatchery, we’re removing pre-zygotic barriers; we put antibiotics in the water, we feed them, we put them all in one area, and remove all predators through a quarter of their life history. That’s a major, significant difference; we’re going to choose what fish we’re going to end up versus what we started with. And I think we need to recognize that we’ve made changes by doing that. That’s all we’re trying to propose. Those are different.”
Question: “Is the Delta as it exists today suitable for the Delta smelt?”
“No,” answered Dr. Moyle. “There are some patches of habitat apparently up in the north Delta, and one of the wonderful things about all this research we’ve been doing is the fact that we do know there are smelt that are spending their entire life-cycle in freshwater. We shouldn’t been surprised by that because some of the old data indicates that, and indeed the captive breeding program suggests they don’t need to migrate to brackish water, but if you focus just on the small pieces of habitat that are up in the north Delta – the Toe Drain and some of these areas, these resident populations can survive.”
“It gets back to this idea of having indirect conservation because for Delta smelt,” continued Dr. Moyle. “If we’re going to really recreate the migratory habitat for Delta smelt, the best hope is to work with the arc of habitat that goes from the Yolo Bypass down Cache and Lindsay Slough down to the Sacramento River and into Suisun Marsh, and to really focus conservation efforts there, including outflows form the river, as that’s where you have the greatest possibility of maintaining some kind of premium habitat for Delta smelt and other species, or recreating it, and that of course means forgetting about the south and central Delta, which to me are a lost cause from the smelt point of view. Right now for the Delta smelt, the problem is the habitat is not there.”
“One of the hardest things about this was we wanted to still make this relatively simplistic guidelines and categories,” said Dr. Baumsteiger. “Everybody is bringing up good points and that’s what this idea is designed to do, get us thinking about these things. But each individual case is going to be unique and there’s no way we can stand up here and define every single one because it would be a 40 page document. There’s actually some people who have attempted to define extinction like in every single case, and nobody wants to read it. It just got into a huge novel book and so it’s a simplistic idea so at least we’re starting to try and move forward on these ideas, to recognize these problems and to deal with them. To be honest about what they are and what we’re dealing with. … We need to at least start dealing with it because it’s a real thing, and it’s really coming, and it’s going to get worse, it’s not going to get better, and so the sooner we start doing it, the better. Maybe these ideas start on a path that maybe somebody comes up with a brilliant idea that no one’s ever thought of.”
Question: “What about the Delta smelt resiliency plan?”
“The Delta smelt is still present in the wild,” said Dr. Moyle. “We still have a small population subject to natural selection. I think as long as we have that small population out there, we should continue to try to figure out how to work with it. The reason that I think we should be able to use the culture population for experiments in the wild is the fact that the genetic studies have been so good and those fish are virtually identical to the wild fish, and I think that we could take a plot, a bunch of eggs and put them out in cages out in the Yolo Bypass and raise them up, so it gives us an opportunity to see if we can actually bring back some of that population at the right time.”
“At the same time, as the Delta smelt resiliency strategy suggests, we need to be figuring out how we can manipulate the environment in ways that benefit the smelt,” continued Dr. Moyle. “There are so many complex issues here, but one of the problems we have is right now we don’t even know what will benefit smelt because there are so few out there, we can’t see what kind of response they will have to environmental change, so that’s why I really push large scale management of the North Delta arc as a way to approach things. If the Delta smelt goes extinct, it’s probably going to be good for a lot of species that are out there, and maybe we can bring back habitat to a point where we’ll have a small window of time where those culture fish might be possible to use them to bring back the Delta smelt, if it’s gone extinct under present circumstances, assuming we bring back some habitat.”
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