Droughts, climate change, and dams: Reconciling a future for California’s native fishes

Dr. Peter Moyle lays out a statewide aquatic conservation strategy for saving California’s native fishes in the face of climate change

Dr. Peter Moyle is a professor of fish biology at UC Davis who has been working with freshwater fishes of California since 1969, and is affiliated with the UC Davis Center for Watershed Sciences and the Department of Wildlife, Fish and Conservation Biology. In this presentation recorded for the University of California Division Agricultural and Natural Resources’ video series, Insights: Water & Drought, Dr. Moyle discusses droughts, climate change, and dams, and how to reconcile a future for California’s native inland fishes.

“I want to start out talking about the drought and native fishes and why this is an issue, and then bring in climate change, because the drought today is doing what we expect climate change to do in the long run, and it is making it much more difficult for fish to survive,” Dr. Moyle began. “Being an optimistic person, I really want to talk about what we can do, describe a conservation strategy of sorts, and then put this in the context of something I’m very fond of these days, which is reconciliation ecology.”

The entire state is in a moderate to exceptional drought for the third year, and entering a fourth year of drought. “You may remember from 2013 to 2014, we went a whole year with virtually no rain, and this was all very hard on the fish as you might expect,” he said.

“What does this drought really mean for the fish in general of California?” he said. “There is less water below dams, and the water is below the dams is warmer as well. This is because there is less water to release. If you cut back on downstream demands for water, you will release less water from the dams, and generally from a fish perspective, what you want are the dams to be releasing water from as deep down in their pool as they can so the water is fairly cold.”

“It also means there’s habitat loss and fragmentation as small streams dry up and as they lose their connection to other streams,” he said.

“More recently, this present week I was up on Hunting and Davis Creeks in the upper part of the Putah Creek watershed, and here you see dry streams,” he said. “Hunting Creek has always been a creek I have loved going to because it had a nice diversity of native fishes in it and was quite accessible, and you see here, just a few little pools left, and they’ll be gone in a few weeks, I’m sure, so this is a creek that normally is a perennial stream, is now dry.”

“This of course means you have major die-offs of fish in many areas as the streams dry up and a great fragmentation of the population, so if you lose fish from a watershed and you want them back again, they have to be able to recolonize from somewhere else, there has to be a refuge for them,” Dr. Moyle said.

Another problem for native fish is alien fish invasions. “Basically we have 50 species of non-native fishes in California,” he said. “Many of them thrive in warm altered habitats such as reservoirs and ponds, and these are habitats that our native fishes don’t do well in, so droughts give alien fishes a new advantage in invading our systems.”

This happened during the 1987-1994 drought, he said. “It really wasn’t a drought as severe as this one, in many respects more a series of dry years, but because the outflows from the Delta got very low in the estuary, we had a series of invasions that changed the whole system,” he said. “The overbite clam, the Brazilian water weed, a bunch of copepods – some of these organisms were already present in the system, but it’s only when the system became saltier and more stressed did these critters get a chance to take off part of that is because the native populations were depressed.”

“It also coincided with increased diversions,” he said. “This is always a problem we have with drought situations. We’re manipulating our waterways very extensively even without drought, so these invaders were given an advantage not only by the drought, but by what we’re doing to the watersheds.”

There are a lot of reasons to be concerned about drought and its effects on native fishes, he said. “First off, the native fishes of California are California fishes,” he said. “79% are found only in the California region, that’s of 129 species. 60% are found in California alone, they are endemic to our state, and another 19% are found in Oregon or Nevada, but generally it’s very small populations on the limits of their range. So if we want our native fishes around, we have to protect them here in California. There are no refuges for them outside the state.”

“Even without drought, 80% of our native fishes are in decline, and 23% are already listed as threatened and endangered species,” he said. “What I’m telling you is not just my own opinion but it reflects a reality that the agencies have come to as well, and more and more species are being listed all the time.”

We know extinction happens; the thicktail chub, once one of the most abundant fish in the Delta, disappeared in the 1950s, and the bulltrout disappeared in the 1970s, he said.

“Even without the drought, the cause of the native fish declines is what I call the one-two punch,” he said. “The first is habitat loss and degradation. We remove a lot of the water from our streams. We dam up our streams, we dry them up, we send the water out in canals, and fish are generally are low priority in the way we manage our waterways.”

“Secondly, then we introduce the alien fishes, and they favor these altered habitats, so native fishes have a lot to contend with, even without drought, if they are going to survive.”

Native fishes are in fact drought adapted, he said. “We live in with the Mediterranean climate,” he said. “The typical year involves all of the precipitation coming down in the winter, and then long hot dry summers with very little rain, so there are natural annual droughts. We also had longer droughts in the past, and these fish show these adaptations to live under these conditions. They are long lived, they have high fecundity so when the good times come back, they can really produce a lot of young. They disperse very rapidly into formerly dry habitats, so they can colonize new areas very quickly.”

Even the salmon in California have multiple runs in year classes, Dr. Moyle pointed out. “They spend multiple years in freshwater or in salt water so they have lots of alternatives over a series of dry years,” he said. “These fish are also designed to take advantage of refuges. These refuges may be spring fed streams, the high upstream reaches that get snowmelt, the large rivers, pools in the some grass moss streams – there’s a whole bunch of places these fish can survive through periods of drought, even under extreme conditions.”

He then showed a picture of a small tributary stream in Lake County that he visited last week. “It’s up in a very hot dry canyon and it was 107 degrees out when we happened to visit,” he said. “The water seemed almost that warm; it’s just this series of little pools of water in this rocky canyon, and yet they contained this native fish called the California roach, which can live under these extreme conditions. Under normal circumstances, refuges like this, perhaps little bigger ones, would keep this fish going through the summer. Even in this area, the deepest pool here was about 1 meter deep, so it’s quite likely these fish will survive through the summer because this is like a bathtub and it’s fairly well shaded by the big rocks.”

From a native fish perspective, California is now in a perpetual severe drought, Dr. Moyle said. “When you have natural droughts, the good times come again and increasingly, we’re not allowing those good times to happen for our native fish,” he said. “Streams become dewatered semi-permanently or have a lot lower flows and they become warmer; access to refuges is denied because of dams and other aspects of the way we manage our rivers so the fish cannot get to the areas that might keep them going through a drought, and then we add competition from non-native species that really make it difficult for these fish to survive.”

That’s why we have to talk about the drought as an example of what’s going to happen as the climate changes, he said. “As I’m sure you know, climate change is already happening,” he said. “And the carbon dioxide has continued to rise in the atmosphere, and the human populations are continuing to grow, and this means that climate change is more of a reality, and this is not good for fish. Of course, it’s not good for people, either.”

“This is all if present trends continue,” he said. “We always have to emphasize that. It’s all about whether or not we really want to do something about these issues or not.”

The predicted effects of climate change on aquatic systems are changes in precipitation patterns in the way rain and snow falls, changes in streamflows, increases in water temperature in general because air temperatures are increased, and increases in the severity of droughts and floods; all of these things will be happening on a more frequent basis, he said.

As for precipitation, the climate change models vary a bit, but increasingly the conclusion seems to be that there will be less annual precipitation on average, he said. “We don’t know how much less, but the general configuration of these patterns is that droughts will become more severe and probably more frequent,” he said. “It’s figured that precipitation will become more variable … most precipitation will occur in the winter and spring. Increasingly this precipitation will occur as rain rather than snow. One of our biggest reservoirs in California is the snowpack in the Sierra Nevada. A lot of that’s going to be lost as water will come down quickly in the winter rather than be held as snow to melt slowly. This makes a huge difference to our streams.”

Stream flows are going to be affected, and this is where the major habitat for our native fishes is, Mr. Moyle said. “Streamflows become more variable, the peak flows in some years will become larger because of the snowmelt issues, and they all occur earlier in the year because it’s warmer,” he said. “The base flows, those are the late summer flows, will become longer and will become lower, so this is going to become a tough environment for fish to live in.”

He then presented a slide of a predicted flow pattern for the Salmon River in the Klamath Basin. “What you’ll notice is that the dotted line shows the altered flows versus the solid line which is historic flows and the altered flows are definitely show you the peaks being earlier, and if you go all the way to September, the flows being lower,” he said. “So hard for fish.”

“Temperatures will increase four to six degrees on average in the air temperature, and somewhere in that same neighborhood for increases in water temperatures, although this depends on stream elevation and size,” he said. “But it does mean that lethal temperatures will occur more often.”

“There will be a large loss of cold water, and by cold water I mean water that is less than 20 degrees centigrade in summer,” Mr. Moyle said. “These cold water habitats will have to shift northwards and then upward in the watersheds in order to have places for our native fishes to live. And the warmer streams in general will favor non-native species.”

These droughts then will show us what happens to our native fishes as climate changes, Dr. Moyle said. “We learn from today what’s going to happen tomorrow, essentially,” he said. “This is a paper a group of us just published last year on the climate change vulnerability of California fishes. We evaluated the vulnerability to extinction in the next hundred years for 121 native fishes and 43 non-native fishes. Basically what we found is about half of the native fishes are already rated as critically or highly vulnerable to extinction, even without climate change, but most non-native species were rated as low vulnerability to extinction without climate change; but when you add climate change to the equation, you find that the numbers jump up to 82% of the native fishes.”

He noted that the bars on the right hand side are the critically highly vulnerable species, and it shows that the native fishes are going to be doing very badly if present trends continue under climate change, whereas the aliens will do much better, and in fact, some alien species will actually benefit from these changes.

“This means most native fishes face severe decline or extinction in the next hundred years while alien fishes will become more abundant, things like carp and red shiners and largemouth bass. Again, I emphasize if present trends continue.”When faced with severe news, the question is what can we do? “It is grim, the future that we’re looking at for native fishes,” he said. “It’s grim because of the increased human use of water combined with the natural changes that will be taking place from the results of climate change.

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“To make this work, we have to develop a statewide strategy for aquatic conservation,” he said. “Right now our conservation is fragmented. We do a bit here and there, we look at individual streams, but when you’re faced with big issues like climate change, you have to deal with them in a big way, and this means developing statewide plans for conservation, especially aquatic conservation. So we have to protect examples of all major habitats; we need self-sustaining populations of all native fishes, and they need drought protections, so those are some of the goals we should be looking at for our statewide plan.”

He then presented a map of protected aquatic habitat in the state and noted that not much of it is protected. “The areas in green are protected habitats that are in wilderness areas, national parks, and things of this nature,” he said. “Most protected areas are in the high mountains where there aren’t many fish, or they are on deserts where there are virtually no fish. Where you have a lot of fish, you tend not to have protected areas, so fish and aquatic organisms in general are not protected by our present system of reserves.”

Dr. Moyle than reviewed the key components that a statewide conservation plan would need.

Native fish rescue facilities: “During droughts, we are going to have periods of time when some species of fish will need to be physically rescued if they are going to survive, and we need to have facilities that are dedicated to keeping some of these fish around,” he said. “There’s a proposed facility at Rio Vista for Delta fishes that includes the Delta smelt that now has a backup population in captivity. We need to repurpose trout hatcheries or build ponds at other facilities statewide that can be used for these purposes. In other words, have backup populations of these fish or places we can put fish if there’s an emergency extinction event going on.”

Statewide database: Maintaining a statewide database of fish is important, he said. “At UC Davis, we developed a statewide database of where fish are found today and where they’ve been found in the past. We’ve got a basic database going already and we’re continually improving it, but this is the information that can be the foundation for any statewide conservation strategy.

For example, you could generate a map like this that shows the conservation status of fish in 1975 versus 2010, and what you see in all the green is where the fish populations are in good condition, and the dark red is where theya re in the worst condition. There’s a lot of green in 1975 and not much green in 2010, and increasing amounts of red and brown through the decades and that’s only a 35 year period. That suggests our fish fauna is in rapid decline.”

Protect the best of what’s left: “Part of the strategy has to be to protect the best habitats that are left and there are still some that are out there,” Dr. Moyle said. “One of my favorites is Blue Creek, where I’ve been working with the Western Rivers Conservancy, who in turn have a partnership with the Yurok Tribe to make Blue Creek into the Yurok tribal salmon sanctuary. This is a tributary to the Klamath River, it supports all the major kinds of fish in the Klamath Basin, and its truly a beautiful spot.”

Restore areas: “Part of the strategy has to be to restore areas,” he said. “This is a project that our watershed center has with the Nature Conservancy to evaluate the restoration of Big Springs Creek, a tributary to Shasta River. Formerly it had been on private ranchland and cows actually grazed in the stream, which is very hard on the salmon. In March, this ranch was acquired by the Nature Conservancy in 2009, and almost immediately, once we fenced the stream and got the cows out, the vegetation started the recovery and the salmon started coming back. Today it is an important salmon stream once again. It still has some problem because of downstream issues, but … just fencing cows out of the stream, and you got this very rapid recovery.”

Improve environmental flows below dams: “Another thing that you have to do is improve environmental flows below dams,” he said. “Our rivers do dry up below dams as they get very low, or become so low it changes the habitat for the fish. We need to have flows below dams that support fish and fisheries. And this is a major issue because we have so many dams in California. There’s hardly a stream in the state that doesn’t have one or more dams on it.”

He then presented a slide from a study on the reoperation of dams. “This is an ongoing study, evaluating the 1400 large dams in the state, and it’s been narrowed down to about 200 candidate dams where flows could be improved for fish; we’re working on some case histories as well. It demonstrates that there’s a lot of opportunities in California for improving flows below dams to benefit fish. And we do have the legal tools to do this – these are widely ignored, but the fish actually have rights in California. Indeed, legally you’re supposed to maintain habitat for fish below dams at all times. These are some very old laws that are on the books, but very rarely enforced. And now increasingly we have to rely on the Endangered Species Act, which is a pretty draconian measure.”

Consider dam removal: “Dam removal is another thing that’s continually being looked at,” he said. “There are some obvious dams like Matilja Dam on the Ventura River to remove for steelhead, but dam removals have to be considered, because this map shows all the areas which are shown in red that are above dams that used to be accessible to salmon and steelhead and other migratory fishees that are now completely cutoff by the dams. And in the Central Valley, 70% of our anadromous salmon habitat is above the dams. One part of this conservation strategy is to figure out which dams can you remove in order to provide access to upstream areas for these fish, because none of these dams have ladders on them for fish to climb.”

Manage floodplains: “Another thing is to manage floodplains,” he said. “We’ve just begun to realize that our native fishes are really well adapted to floodplains … Salmon grow about two or three times as fast on the floodplains, and it’s just a matter of providing them access to it. They know how to get on and they know how to get off. One of the key floodplain areas that we’re currently studying and being looked at for management for native fish is the Yolo Bypass.”

“How do you do all of these things? How do you make a system work where you have such drastic things you need to do?,” he said. “I think you need to adopt a whole new approach to conservation called reconciliation ecology which recognizes that humans dominate all ecosystems. We’re in charge; we’re the dominant species on this planet and it doesn’t matter where you go, we’re there.”

“Most ecosystems are also novel ecosystems, which means they are mixtures of native and non-native species in altered habitats creating ecosystems that have never existed before. We’ve created new ecosystems and we have to understand how these systems work and how we can manage these systems so they benefit the species we want, in this case, native fishes,” he said.

“Drought and climate change are just increasing the need for this general approach of recognizing that we need to take charge and make the hard decisions about what species we want around in the future,” he said. “Our big question then becomes how do we incorporate conservation into human dominated ecosystems? Obviously, from what you’ve heard, this is not going to be easy.”

He then concluded with a case study of Lower Putah Creek, one of his favorite places. “This is a creek which is regulated by dams, and the reach that flows by campus is regulated by the Putah Creek Diversion Dam, which is basically a 30 kilometer long riparian shred that is a deeply incised creek that meanders through a highly agricultural landscape and is a major place for fish and wildlife in this region.”

It’s an incredibly novel ecosystem that is a mixture of native and non-native species, and it’s also a model for a reconciled aquatic and riparian ecosystem, he said. He presented a picture of the creek taken in February before the meager winter rains, and noted that there is still water in the creek. “This creek has been flowing steadily all through this drought period,” he said. “This is because it’s a managed stream and it’s managed to produce water under drought conditions.”

“This is not a natural habitat,” he said. “This is why it is a novel ecosystem, it is this narrow ribbon of habitat with dykes on both sides going through some of the best agricultural land in the world that’s very intensively farmed.”

He presented a chart of species found in Putah Creek and noted that it’s a wild mixture of native and non-native species from all over the world. “When you look at plants, the weeds, 61% are non-native species, 63% of the fish are non-native, and of the amphibians, one-third are non-native, so what you see is that this is a system that contains a lot of non-native species and it’s a mixture of both in this very altered environment.”

As a result of a lawsuit, the flow regime was changed to one that mimics natural flows, he said. “The natural flow regime was designed to enhance native fishes at a very low water cost, and what you see … is that before the high flows were instituted, we had a stream that was largely dominated by alien species. Once we created a flow regime that favors native fishes, that abruptly switched to about 80% natives in these areas. What’s interesting to me is that the alien species did not go away, they just became much less abundant.”

So if Putah Creek is to serve as an example for streams throughout California, what does it take to manage it as a reconciled ecosystem?

“It takes vision,” Dr. Moyle said. “You have to really look at this stream and say what do you want in the long term? This vision was expressed in the Putah Creek Accord which, in this case, which was the result of a lawsuit. It would be nice if we didn’t go through a lawsuit to get water in our streams. It takes water agency cooperation – the Solano County Water Agency is now a very proud cooperator in managing the stream. One of the best thing is there’s a streamkeeper, a full time employee now of the water agency, whose job is to look after Putah Creek, look at the conservation, raise money for restoration projects, work with landowners, do everything he can to make the stream as good a place for native fish and wildlife as he possibly can.”

“It takes community involvement,” he continued. “The towns along the creek are involved, and we have an environmental group, the Putah Creek Council, that is very deeply involved in restoration activities. It takes landowner cooperation, most of the land along the creek is privately owned, and it needs monitoring. Indeed, part of the Accord agreement was that this water agency would pay for monitoring of the fish and wildlife along the creek so we know what’s going on. And it’s working, that’s the bottom line. It’s not easy, but it’s working.”

“And obviously money is needed, and lots of it,” he said. “This is a matter of considering it to be an investment in the future. There’s so much to be gained if you can avoid getting fishes listed as endangered species, and there’s so much to be gained by having streams that flow through neighborhoods that people like to go down to. Putah Creek was a mess before the Accord; now it’s a place people like to go down to, see the fish, to recreate, to watch the otters, and whatever else. I recommend a blog that was written by Jay Lund et al of our watershed center on about how we’re giving away fish flows for free during droughts when we really should be paying for that water. Water that belongs to the fish really should be paid for.”

“So the conclusion then is that systematic actions are needed to save California’s endemic fishes,” he said. “We can do it. We need them in the short term – this drought is apparently going to get worse before it gets better and it may take some emergency action in the not to distant future. We need more places like Putah Creek which has right now a flow regime that acts as a refuge for native fishes. We know climate change is accelerating the rates of decline, and we can see extinctions on the horizon if we don’t really do something. And this 2012-14 drought is an example of what is to come.”

“But again, it’s only if we let present trends continue, and I can’t emphasize that too much,” he said. “If we’re going to think of ourselves as being reconciliation ecologists, we can really make our systems work, and work in ways that are good for people and good for the fish and our rivers.”