A.B. 2376: Opening the Door to Restructuring the Department of Fish and Game

In late September California governor Arnold Schwarzenegger signed A.B. 2376 into law. This bill was supported by numerous fishing groups, including California Trout, Trout Unlimited, and The Sportfishing Conservancy, and was motivated by the recently-released Treanor Report that suggested changes to how the California Department of Fish and Game (DFG) and the California Fish and Game Commission (FGC) are structured (Treanor Report available here). A.B. 2376 requires that the Secretary of Natural Resources convene a committee to "develop and submit to the Governor and Legislature, a strategic vision for the Department of Fish and Game (DFG) and the Fish and Game Commission". Specifically related to the management of fish and game, it requires the following:

"....that the strategic vision address specified matters relating to fish and game management, including but not limited to: biodiversity management and ecosystem functions; permitting and regulatory functions; recreational and commercial harvest; scientific capacity; relations with the public, landowners, nonprofits and other land management agencies; reforms necessary to address challenges of the 21st Century; use of technology and data systems; clarification of the roles of DFG and FGC; and strategies for identifying other stable funding options to reduce DFG's dependence on the General Fund."

That is a pretty broad statement so who knows what will come of it. But the DFG and the FGC both certainly need to be updated to better accomplish their respective missions. One change that would be high on my list of priorities is for the DFG to increase its scientific capacity and to use science (instead of political expediency) to resolve resource-related disputes. An increased capacity to conduct critical resource-related scientific studies would go a long way toward allowing the DFG to anticipate resource problems. This proactive position would provide for far better decision-making than the current DFG model which seems to be to ignore growing issues for as long as possible and then deal with them in crisis mode when forced to by outside pressure. As I've said many times before, science will not provide all of the answers to our resource issues but it can provide a solid foundation upon which rational solutions can be developed.

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Mitigating the Effects of Chytridiomycosis

For the last couple of years our research group has conducted several field experiments aimed at understanding the extent to which we can change the outcome of outbreaks of the amphibian chytrid fungus (Batrachochytrium dendrobatidis - "Bd") from frog population extinction to persistence. This summer and last we treated frogs at die-off sites with anti-fungal drugs, something I never in my wildest nightmares imagined that I'd ever be doing. My field crews and I put everything we had into those experiments but so far success remains elusive. 

Given our attempts at changing disease outcomes I was excited to attend a disease mitigation workshop last week in Zurich, Switzerland and learn what other researchers from around the world have been trying. Over a two day period we learned of each others myriad efforts to confront the Bd plague and were sobered to realize that all of the attempts at changing Bd disease outcomes attempted so far have failed. 

At a Bd-positive site in Mallorca (Spain) Jaime Bosch and his colleagues removed all of the amphibians, treated them in the laboratory with an anti-fungal drug until they were Bd-free, and then completely dried the pond. When winter rains refilled the pond the treated tadpoles were released back into the site. Much to everyone's surprise by spring the tadpoles were once again infected with Bd. Given that Bd apparently does not have a resistant stage that could survive dessication it remains a mystery how Bd survived at the site or reinvaded so quickly (additional details are provided here). 

A graduate student at the University of Zurich, Corina Geiger, recently conducted an experiment in which she established frog populations in large outdoor tanks which she subsequently infected with Bd. Once the frogs showed evidence of chytridiomycosis she treated the entire tanks with antifungal drugs. For six weeks following treatment frogs were uninfected, but then Bd reappeared and reinfected the frogs. These results mirror our own results to date in the Sierra Nevada. 

Other mitigation efforts are currently ongoing, including an experiment using frog skin bacteria that have strong anti-Bd properties (additional details provided here), and another in which amphibian densities are being temporarily reduced to assess the effect on disease dynamics.

The ineffectiveness of the anti-Bd treatments attempted to date is obviously disappointing and illustrates just how incomplete our understanding of Bd still is. If we do stumble across an effective mitigation strategy it seems it will be almost entirely a stroke of luck. And yet, with Bd spreading into new uninfected populations with every passing month, we don't have the luxury of waiting for better information.

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An Unnatural Quiet

This summer I returned again to one of the Sierra's most remote lake basins to resurvey the amphibian populations there. This basin holds a special place in my heart due to its spectacular beauty, isolation, and at one time, an incredible Sierra Nevada yellow-legged frog population. The first time I visited this basin was in 1997 when my assistants and I conducted our initial surveys of its frogs, fish, and invertebrates. Back then, the sheer number of frogs was overwhelming. 

I remember counting 10,000 tadpoles in a single lake. The frantic swimming of these tadpole masses at my approach turned the tranquil water surface to a muddy froth. Adult frogs seemed to occupy every possible bit of water; nearly every lake, pond, stream, and puddle was full of them. As I walked along one lake shore, a frog dove off of a damp ledge ten feet above my head and with legs splayed wide splashed into the water at my feet. The abundant bears in this basin seemed just as fond of the frogs as I was. In several spots where tadpoles aggregated by the thousands, I saw where bears had waded out into the water to catch them. One evening I watched a Clark's Nutcracker land at the waters edge and spear a tadpole. With the tadpole in its beak it flew to a nearby snag, snipped off the tadpole's tail, and fed the body to a begging fledgling. Transfixed, I sat down and watched the show repeat itself several more times. When the adult and fledgling had flown away I walked to the snag and saw that the branch the fledgling had been perched on was covered with 50 or more tadpole tails, some dry and shriveled, some still wet. What an incredible web of life these frogs were a part of!

Back then the world was unaware of the amphibian chytrid fungus (Batrachochytrium dendrobatidis - "Bd") and its devastating effects on amphibians around the globe. I took it for granted that given the paucity of trout in this basin the frogs would always be there, for the bears, for me. A few years later Bd arrived in the basin, causing the collapse of one frog population after another. Within five years the frog numbers had decreased by 95% but I still held out the hope that maybe a few would survive to repopulate the lakes. 

Our resurveys this summer showed that even that modest hope was too optimistic. Most water bodies were now entirely frogless. A few contained only a single adult frog. We found some tadpoles, but too few to give us much hope that the population would still be there the next time we did our resurveys. 

Sitting on a lakeside boulder eating my lunch in the summer sun, I couldn't help notice how quiet the basin had become. No more frothing masses of tadpoles. No frogs jumping into the water by the 10s and 100s in front of me as I walked along the shoreline. Bear sign, once so common, was far less in evidence, although I did see one set of bear tracks that went into the lake where a few tadpoles still basked in the warm shallows, but the paucity of animals would hardly have made a snack much less a meal. No Clark's Nutcrackers eating tadpoles. The mayflies, caddisflies, and beetles were still there, but the once-dominant frogs and the web of life they once supported were gone.

When I first happened upon this place it was defined by the frogs, frogs as predators, frogs as prey, frogs as inhabitants. Now it was different. In the span of less than a decade, a shangri la had become a place of ghosts.


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Back from a Summer in the Mountains

It has been months since I've added any posts. My only excuse is that I've been in the mountains almost continuously since mid-June conducting research. I've been impressed at the number of people who emailed me during my absence from the blogosphere to make sure I hadn't abandoned my practice of regular posts related to the mountain yellow-legged frog. Rest assured that I have not. Now that my field season is over I'll do my best to again provide updates on a more regular basis. 

Of the many frog-related happenings that occurred this summer, perhaps the most important was a decision on September 15 by the California Fish and Game Commission to designate the mountain yellow-legged frog (both Rana sierrae and Rana muscosa) as a "candidate" species under the California Endangered Species Act (CESA). This action was taken in response to a petition submitted earlier this year by the Center for Biological Diversity. The California Department of Fish and Game now has one year to develop a formal status review that will recommend whether or not the mountain yellow-legged frog should be listed. 


During the one-year review period, the CESA requires that candidate species be treated as if they were already listed. This is an important difference between the Federal and California Endangered Species Acts. Under the Federal ESA, a candidate species has no formal status until it is actually listed. Because of the potential for the new "candidate" status of the mountain yellow-legged frog to immediately impact a wide variety of ongoing activities the Commission adopted a series of "take" exemptions (i.e., exemptions for actions that could potentially result in harassment or mortality of mountain yellow-legged frogs). 

Exempted actions include those for the Department's ongoing fish stocking programs (no surprise there), timber harvest, reservoir operations, and scientific research. Although some have expressed their displeasure with these exemptions, I support them because they will provide individuals and agencies with some breathing room to continue already-permitted activities during the one-year review period. The negatively publicity that could result from an immediate shutting down of these existing projects (especially fish stocking) would likely have more long-lasting negative effects on frog conservation efforts than these projects would. 


So, by next October we'll get an up-or-down vote by the Commission on the listing status of the mountain yellow-legged frog. If the frog is listed under CESA I suspect that efforts to conserve and restore populations of this imperiled species will ramp up to a level not yet seen.


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Captive-bred Frogs Released into the Wild for the First Time

The southern mountain yellow-legged frog (Rana muscosa) inhabits lakes, ponds, and streams in the southern Sierra Nevada and southern California. The southern California Distinct Population Segment (DPS) was listed as "endangered" under the federal Endangered Species Act in 2002. This DPS currently contains fewer than 200 adult frogs and these remaining populations are at extreme risk of extinction due to a myriad of threats.

In response to the perilous status of this southern California DPS, scientists from the U.S. Geological Survey and San Diego Zoo have been working to develop an indoor captive breeding population the could eventually produce sufficient offspring for release into the wild. In an effort to stimulate frog breeding, this spring captive adult frogs were refrigerated for several weeks to simulate winter conditions. Once temperatures were increased frogs quickly began breeding, resulting in the production of numerous egg masses. 

In mid-April several of these egg masses were moved to a creek within the James San Jacinto Mountains Reserve, a reserve managed by the University of California. This is the first time that captive-bred mountain yellow-legged frogs have been released into the wild, and represents an important milestone in the recovery of frogs in this DPS. Time will tell how well the released animals survive. 

In addition to aiding the conservation of mountain yellow-legged frogs in southern California, these efforts have also produced a wealth of information regarding the breeding of these frogs in captivity. Whether we'll ever need these techniques for restoring mountain yellow-legged frogs in the Sierra Nevada remains to be seen but it is nice to have these methods already worked out. I continue to believe that one of the highest conservation priorities for Sierra Nevada frogs is to develop several outdoor captive populations of frogs in artificial ponds at an accessible location. Such populations are much less expensive to maintain than indoor captive populations (frogs don't need to be fed, water doesn't need to be changed, etc.) and would provide lots of offspring for use in research and conservation. All we need is a few ponds. Efforts to identify suitable ponds are ongoing.


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Two New Papers Detail Impact of Disease on Sierran Frogs

Two papers by our research group were published today in the journal, Proceedings of the National Academy of Sciences (PNAS). Both papers are open access and can be downloaded from the PNAS web site (Vredenburg et al. paper; Briggs et al. paper). These papers represent more than a decade of research by our group on the role of the amphibian chytrid fungus (Batrachochytrium dendrobatidis - Bd) in driving the decline of mountain yellow-legged frogs in the Sierra Nevada.

The first paper (by Vredenburg, Knapp, Tunstall, and Briggs) describes the frog-Bd dynamics in detail for the first time and provides a critical insight into how Bd outbreaks might be controlled. Bd was absent from the three study basins at the inception of the research but invaded the basins in 2004-2005. Following its initial arrival Bd spread through the basins at 0.6 km per year, eventually infecting all mountain yellow-legged frog populations. 

Within 1-2 years of its first detection in a frog population, the population began to show evidence of severe chytridiomycosis (the disease caused by Bd). Frog die-offs and population crashes occurred when infection intensities (amount of Bd on a frog's skin) reached a critical threshold. The fact that a disease threshold exists is important because it provides a target for intervention strategies, strategies designed to prevent infection intensities from surpassing this threshold. One strategy, clearing frogs of Bd using an anti-fungal drug, was tested in two of the study basins in 2009 and preliminary results are promising. We'll be conducting additional tests in 2010, one designed to investigate whether clearing frogs of Bd early in an epidemic can actually prevent the epidemic from occurring.


Although most frog populations are extirpated following Bd epidemics, a few persist despite ongoing chytridiomycosis. Scientists have suggested that this persistence could be a consequence of selection for reduced susceptibility of frogs or reduced virulence of Bd. In the Briggs et al. paper, we use a mathematical model to demonstrate that neither of these changes are necessary to explain the long-term persistence of infected frog populations in the presence of Bd. Instead, this outcome could be solely the result of density-dependent host-pathogen dynamics. Under this scenario, epidemics are the result of Bd invading naive frog populations existing at their naturally high densities. This allows the production of vast numbers of zoospores (the infective stage of Bd) that overwhelm any frog defenses and causes massive frog die-offs. Most populations are extirpated but frogs in a few populations survive by chance alone. In these populations, zoospore density is kept low by low frog numbers, and frogs are able to tolerate the resulting low Bd infection intensities. As a consequence frog populations persist at low densities with Bd over the long term. 


This model assumes no role for an adaptive immune response by frogs against Bd. Although this is consistent with our current knowledge of the frog-Bd interaction, a series of experiments we are currently conducting will provide clearer insights into the existence of any such response. 


For the first time in several years I feel like we are making substantial progress toward understanding and potentially controlling chytridiomycosis. Let's hope our advances haven't come too late.

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Impacts of Fish Stocking on Willow Flycatchers - Really?

As opening day for trout fishing season approaches, stories in the local papers often dwell on impending issues that might affect the number of fish stocked and stocking locations. Last year the stories focused primarily on issues surrounding the court order that mandated that the California Department of Fish and Game (DFG) prepare an environmental impact report detailing the effects of its fish stocking program. This year the stories have focused almost exclusively on the concern that the presence of willow flycatchers could preclude fish stocking. All of the media stories that I've read on this issue have failed to provide much context for this issue, focusing instead on how outside environmental groups are to blame for the current "crisis". The following is my attempt at clarifying how the willow flycatcher got wrapped up in the fish stocking issue and what the current DFG plans are related to this species. 

When I read the DFG fish stocking EIR-EIS I was quite surprised to see the willow flycatcher listed as a "decision species" ("decision species" were defined as those species potentially affected by hatchery and stocking programs). My surprise stemmed from the fact that there were no published studies suggesting such impacts on willow flycatchers. Furthermore, the interim court order that was developed jointly by the Center for Biological Diversity, Pacific Rivers Council, and the DFG (the intent of which was to prevent harm to sensitive species while the EIR-EIS was being written) focused only on fish and amphibians (13 and 11 species, respectively). So, how did the willow flycatcher end up in the EIR-EIS as a decision species? 

It turns out that it was the DFG that added the willow flycatcher to the decision species list, and without any prompting from environmental groups or the public at large. The rationale was basically that trout and willow flycatchers both depend on insect prey for a large proportion of their diets. Because the introduction of trout into mountain lakes dramatically reduces the biomass of aquatic insect larvae and the subsequent emergence of adult forms of these aquatic insects, the DFG reasoned that this reduction in adult aquatic insects could reduce prey availability for willow flycatchers. The willow flycatcher was on the DFG "radar screen" because it is listed as "endangered" under the California Endangered Species Act. 

The possibility that trout stocked into aquatic ecosystems could affect adjacent terrestrial ecosystems is a fascinating area of ecological study, and recent research in the Sierra Nevada shows that stocked trout have in fact altered the distribution and foraging habits of the Gray-crowned Rosy-Finch, one of the few species that nests in the alpine zone. This soon-to-be-published study provides evidence that trout-containing lakes had 98% fewer mayflies than did neighboring fishless lakes, and that Rosy-Finches were six times more abundant at fishless lakes than at fish-containing lakes as a result (mayflies make up a significant fraction of Rosy-Finch diets during the emergence period). However, it is a stretch to extend these Rosy-Finch findings to willow flycatchers, but that is exactly what the DFG did. 

In the EIR-EIS the DFG suggested that impacts of trout on willow flycatchers were possible, and proposed to mitigate these impacts by conducting a "pre-stocking evaluation" at each mountain lake that receives hatchery trout and that lies within the range of the willow flycatcher. As stated in the EIR-EIS (page 4-100), "Under the protocol, each stocking location shall be evaluated in a stepwise fashion to determine whether interactions between stocked trout and willow flycatchers may occur and to evaluate the potential for trout stocking to result in an (sic) substantial effect on willow flycatchers. If such an impact is determined likely, then DFG shall either cease stocking at that location or develop and implement, prior to stocking at that location, an ABMP". (ABMP = Aquatic Biodiversity Management Plan).

With the EIR-EIS finalized in January of this year, the upcoming opening of the trout fishing season is the first in which all fish stocking is required to meet the guidelines specified in the EIR-EIS. The range of the willow flycatcher includes the eastern Sierra Nevada so technically no lakes can be stocked in preparation for the season opener unless a pre-stocking evaluation for willow flycatchers has been conducted, and until a few weeks ago no such evaluations had been conducted for stocked waters anywhere in California. And how can evaluations be conducted when most mountain lakes are still surrounded by snow and it will be weeks before willow flycatchers arrive to breed? The DFG has been scrambling to figure this out and the ensuing confusion has generated a slew of rumors, including how the Center for Biological Diversity forced the DFG to include the willow flycatcher in the EIR-EIS and how the willow flycatcher is being used as an excuse by bureaucrats in Sacramento (including DFG bureaucrats, in some version of the rumors) to shut down the fish stocking program. That these rumors have little basis in fact has not stopped the local media from reporting and elaborating on the rumors and innuendo. 

So, here is my take on all of this. While I applaud the DFG for acknowledging that fish stocking impacts likely extend beyond the water's edge and can in some cases impact songbirds and other terrestrial predators, it is ill-advised to change fish stocking management without a scientific rationale. There are no data suggesting that willow flycatchers are negatively impacted by fish stocking. The current lack of evidence certainly does not indicate that no such impacts are occurring, but the lack of any scientific evidence makes designing effective mitigation essentially impossible. I would have much preferred a more cautious approach in which the DFG acknowledged the potential for impacts of fish stocking on willow flycatchers and committed to studying the issue over the next year. Subsequent management actions and mitigation could then have been designed based on the results of the accumulated evidence.


I never thought I would criticize the DFG for being overly aggressive in developing mitigation strategies to reduce impacts of fish stocking. Go figure.

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