Now that I’m not in the field these updates are getting a little harder to write. I officially have a “desk job,” and there isn’t much exciting about it on a week-to-week basis. For those of you who are wondering, the introgression manuscript continues to make progress. I’m starting to be a little less stingy with some of the results now that the analysis is complete and I’m confident that the numbers are correct. But, I’m not putting anything into writing until the manuscript has been vetted against all the important people that are above me in the academic food chain.
Last week, I did get a chance to get out from behind my computer. But, instead of hitting the streams of Loyalsock, I traded my office chair for a seat in a kindergarten classroom. My advisor, Ty, asked me to help him put on a short demonstration for the kindergarteners at the local elementary school. Having really minimal experience with kids, and a lot of uncertainties about our ability to keep the fish alive and well for a few hours, there was a lot of doubt on how this was going to go off.
But, it was a lot of fun. Kindergarteners make the best amateur fish biologists. They still find slimy things cool, aren’t afraid to touch everything, and ask some of the best questions.
“Do fish have bones?”
“Will it eat my finger?”
“What do fish drink?”
“Why does it have spines?”
“Why is he puffing his cheeks out?”
“Why are those lobsters fighting each other?”
Okay, so maybe we didn’t explain the ID for crayfish all that well. But, these endless questions reminded me of why I got into science in the first place. I can ask a question about this thing I don’t know much about, and someone will have the answer. And, if they don’t have the answer, I can go find it out for myself.
Obviously science gets much complex than kindergarten queries. And, science is down right hard sometimes. Long hours, lots of confusion, lots of times you feel stupid and wrong. But, those hardships only become true burdens when you start asking questions that don’t excite you. It’s easy to hate science when you study something that you, deep down, don’t care to know the answer about. It doesn’t help that the scientific process is sometimes riddled with extraneous steps that can keep you from pursuing your curiosities.
So, deep breath. Step back.
I’m just out here, trying to ask and answer questions that get me excited. To that end, I’m making a new rule. When my face stops looking like that of the girl’s above- sheer excitement, curiosity, and wonder, I’m quitting.
(If you’ve seen me net a large trout, you know I’m nowhere close to quitting.)
We’re so close to submitting our introgression manuscript! This is always one of the most exciting, but also one of the most torturous stages of manuscript preparation. You’re so close to being done (at least until reviews come back), and at this point so tired of working on this one project. But, there are so many tiny little things you have to do before you hit submit- check, recheck, and triple check all your statistics, make sure the format is correct (every journal has their own requirements for what should be bolded, italicized, word counts, etc.), confirm the address of your coauthors, etc. The exciting science is basically over, and now it’s more administrational tasks.
This is part of science and graduate school that I never knew about until I started down this path. I still have my fair share of days spent getting my hands wet, holding fish, analyzing data, and being generally confused. You know, all the things I knew science and research entailed. But, there are some jobs, and some parts of jobs, that I never really knew would be part of my career at this stage.
So, for all those out there feverously preparing their graduate school applications, or just wondering what it’s like to be an early career fish biologists, here’s the top five things I never knew I’d be doing at this phase of my career.
Warning: Sappy post ahead
Yes, I disappeared again. I’ve been traveling the Rockies- a trip that was initiated by the Wild Trout Symposium in Yellowstone, and then quickly got out of hand when I decided to tack on a few vacation days after realizing how close all of the national parks are. I obviously use the term “close” loosely here, and my bright ideas received further encouragement by my inability to look at the scale bar on a map. But, after nearly 3,000 miles, three national parks (Badlands, Yellowstone, and Grand Tetons), a national memorial (Mount Rushmore), a national monument (Craters of the Moon), and eight states, I am officially working my way back towards home. Very slowly I might add- I’m currently overlooking the sunset over Great Salt Lake from Antelope Island State Park (state park #2, for those counting) before catching the red eye back east.
It goes without saying- this was a trip of a lifetime. But, maybe for reasons that aren’t so obvious. Yes, the parks were gorgeous. I’m already planning my trip back. You can’t help but be amazed by the geological and biological wonders of this region. And, I got close enough to pet a bison on multiple occasions (I didn’t…my advisor warned me it would not end well).
But, I kind of expected most of that to happen. What I wasn’t expecting was to walk away from the conference so inspired. The Wild Trout Symposium gave new breath at just the time when a PhD student needs it most. Don’t get me wrong, I love my research. I cannot possibly imagine a better project, and there are very few days where I don’t love coming to the office. But, sometimes you get caught in the weeds, especially as you’re trying to string together the analyses, appease reviewers, write papers, and run the rat race of academia.
And, while I also enjoy larger meetings (like the American Fisheries Society meeting I attended in August, which always has attendance in the thousands), there is something special about speaking to “your people.” The people who love trout, study trout, and work harder then you to protect and conserve trout. It was interesting to hear about the research advances and conservation challenges that others are facing around the world and across all trout species. It really helped put everything into perspective about the more global significance of the work that is happening in my little corner of the trout world.
At the meeting, I also realized more than ever that I’ve grown. A lot. Science education happens very slowly, and there are very few benchmarks for measuring success. You can take tests and get degrees, but those don’t necessarily measure your ability to practice sound science. Soon I’ll be trying to convince my defense committee that I’m worthy of a degree, and the thought of it is panicking- do I really know enough science to deserve a doctorate? Hard to say, and I think the more degrees you get the more you recognize that you’ll always wish you knew more.
But, I was reminded this week that while I still have (and will always have) a long way to go, I’ve also come a long way. At the meeting, I was honored to win the Marty Seldon Scholarship. The person presenting the award was a member of my Master’s committee, and was almost certainly in attendance the first time I presented at a fish conference. He said the traditional mumbo jumbo- my degree, my school, my project, but then went off script to express how proud he was of the scientist I had become. It meant a lot, and reminded me of the knowledge base (or lack thereof) I had when I first started working in fisheries about 10 years ago. I’d sit in the audience at conferences, having no idea what people were talking about and praying no one asked me questions about my own project. Today, I’m winning awards and serving as a source of advice and knowledge. Crazy. I still, and will forever, have a lot to learn. But, I’ve grown. I’m getting better. Something I’m doing is working.
Part of that growth is being able to recognize the significance of a research project. And, there was some great research presented at this meeting. Unfortunately, many of the presentations painted the same dark picture we all know have come to associate with native trout conservation. Habitat is tanking, temperatures are rising, diseases are becoming more common, harvest regulations are inadequate, and hybridization could mean the end to entire species. It would normally be enough to make a trout lover walk away extremely disheartened and hopeless.
But, I didn’t. I walked away more confident about the future of trout populations that I had been before because I realized that there are some amazing people in this field. It’s a group of biologist that work tirelessly and are making some great advances in the ecology of wild trout management. We’re moving away from the emphasis on stocking and towards a more holistic approach to conservation. Everything from genetics to metapopulations, habitat improvements to angler satisfaction. It all needs to considered to get the harmonious balance needed to have a chance of conserving wild trout. And, the group gets that.
The next hard step that many people identified was now getting all of that science into the hands of managers, anglers, and citizen scientists. We can’t keep managing our resources in ways that we know defy science, but we also can’t change our management when the science is unknown or untrusted. So, my only criticism of that meeting was that I wish you, the angler group that I think comprises the majority of my readership, could have bene there. I think one of the missing pieces of the puzzle at this meeting, but also in general management, is the union between scientists and the public. We’re living in separate bubbles to a large extent, and until we close those gaps we’ll continue to struggle to find the happy balance. Nothing is new on that front, but it’s more justification for why things like this blog and other outreach initiatives are so vital.
Even in a perfect world, I don’t expect the fight for native trout to ever get easy. I think one of the lines that echo in my mind was from a presentation from the Yellowstone National Park Superintendent. He talked about their efforts to restore populations of Yellowstone cutthroat trout, which are declining due to habitat loss and invasion by nonnative fishes. At the end, he mentioned some of the hurdles associated with Yellowstone cutthroat trout conservation, and overwhelmingly he noted that he never dreamed that the fight for wild trout conservation would be met with so much resistance. If Yellowstone struggles to restore wild trout, how will all the tiny streams with brook trout possibly fair? I’m not sure, but I have no doubt that we’ll keep putting up a good fight.
Exhaustion has set in, and I’m now sitting in terminal A of the Salt Lake City Airport awaiting my midnight boarding call. I’m tired, I’m behind on work, but my head is clear and drive is restored.
Wild Trout XII was a success.
Sorry, folks. I'm copping out this week. I'm on the heels of another conference, and the there's a tornado of activity as I try to wrap up loose ends at the office before embarking on an eight-state, 12-day tour of the mid-west. Badlands, Rushmore, Bozeman...quick conference in Yellowstone....Jackson Hole, Salt Lake. I live the silver spoon grad school life.
In all seriousness, my advisor is more than generous with his allocation of resources and supports me making these trips. Not all advisors give their students the freedom to attend expensive conferences. But, I also help my cause and do some of my own fundraising. A few days ago I was honored to be named a recipient of the 2017 Marty Seldon Scholarship to offset some travel costs to the Wild Trout Symposium in Yellowstone. The application was fairly straightforward- an essay describing my research, involvement in professional fisheries organizations, and what I feel are the most pressing issues in trout conservation.
Below is my submission. For many of you seasoned readers, you already know the spiel. For some of you newer readers- sit back, learn a little about me, my research, and what I'm fighting for.
Conservation of wild trout populations is met with a myriad of challenges with none more pervasive than climate change. Look no further than the northern-receding margins of the eastern brook trout’s range, collapse of cutthroat trout populations in the Rockies, and declines of European brown trout to find evidence that climate change is threatening salmonids worldwide.
Managing coldwater fisheries under climate change is a complex problem of scale. Large-scale changes to stream temperature, flow regimes, and habitat availability transcend watershed and political boundaries, often making management logistically and financially unfeasible. Yet, there are also small-scale changes to species interactions, population vital rates, and individual fish physiologies that are not only difficult to manage, but also remain poorly understood. Together, the effect that climate change has on trout populations within and across scales produces unanticipated, nonlinear patterns and dynamics that reduce our ability to predict future outcomes of habitat loss and effectively manage trout populations.
The efficacy of present-day management objectives, which largely focus on increasing population sizes and habitat availability, will only continue to decline as climate change outpaces restoration efforts. Accordingly, management must become more forward thinking and include conservation of the fine-scale properties that naturally increase population resistance and resilience to habitat loss. To accomplish this goal, a better understanding of individual variation is needed to answer questions such as: why are some populations and individuals more fit than others, are there specific genes that lead to higher thermal tolerance, why do fish behave differently from one another, and is individual variation important for population survival?
These are just some of the questions I am addressing in my dissertation research at Pennsylvania State University in the lab of Dr. Tyler Wagner. Specifically, I am merging the fields of genetics, behavior, and population ecology in a series of field and laboratory studies to investigate the adaptive significance of intraspecific variation in native brook trout populations in Pennsylvania.
At a molecular level, I am studying population genetic structure to identify spatial patterns in genetic diversity. While previous studies suggest that brook trout populations readily isolate at small spatial scales, my research suggests that genetic connectivity and diversity remain high near mainstem river corridors as compared to headwater populations. This suggests that the processes that maintain metapopulation dynamics differ across the species’ range. Further, because genetic diversity is correlated to adaptive capacity and resiliency, the location of a population within a stream network could predict evolutionary potential and extinction risk.
I am also completing one of the first studies of gene expression in wild trout populations to quantify expression patterns of heat shock protein 47 (HSP47), a common indicator of thermal stress in fishes. In total, I evaluated gene expression for nearly 700 fish using non-lethal gill and blood samples collected every 1-3 months for over a year. Preliminary results suggest that HSP47 expression is highest in early spring, and nearly absent in summer when stream temperature is warmest. This suggests that brook trout begin expressing heat shock proteins in response to mild increases in stream temperature, and that there is a limit to how much HSP47 can be produced before gene expression stops. Ultimately, these results could indicate a limited scope for adaptation and plasticity in stress protein production.
To determine how intraspecific genetic and behavioral variation influence population structure and survival, I completed a multi-season telemetry study on 180 wild brook trout distributed across four tributaries to Loyalsock Creek, Pennsylvania. From this work, I documented significant individual variation in behavior, including some fish that completed large-scale, post-spawn movements to overwinter in mainstem Loyalsock Creek; a system largely considered unsuitable for brook trout prior to my study. Taken together, the observed zero-centered leptokurtic distribution in movement and patterns in population genetics describe above suggest there may be multiple life history strategies in some brook trout populations, including some highly migratory individuals that disproportionately increase genetic connectivity among populations. In the future, I will complete a genome-wide association study to identify specific genes that correlate to different movement patterns.
In the lab, I am completing several studies to determine whether inter-individual differences in behavior can be explained by fish personality. While it is understood that personality can modulate growth, reproduction, and mortality, the ecological and evolutionary significance of personality has not been rigorously explored in any taxa. I determined that boldness, the most studied personality trait in fish, reduces spatial learning ability. This finding suggests that phenotype influences learning and memory processes, and could explain differences in habitat use and movement among individual trout. I am currently conducting another lab study to determine how boldness influences the ability of fish to compete for resources at different stream temperatures. I hypothesize that the higher metabolic demand of bold fish will decrease their success at defending resources at higher temperatures.
Though I hope to increase the efficacy of trout management with novel research objectives, I am equally passionate about improving conservation through communication. I am the first author of seven peer-reviewed manuscripts ranging in topics from long-term stream habitat management to social learning in trout. I have also given over 20 presentations at state and national conferences, many of which receiving best paper awards.
In addition to professional communication, I continually seek opportunities to interact with the public through outreach and education. I am particularly passionate about introducing prospective biologists to stream ecology within the framework of professional service. For example, my election to President (Virginia Tech Chapter), Membership Chair (Virginia Chapter), and Social Media Coordinator (National Chapter) of AFS has afforded me the opportunity to lead educational programs and workshops for students and professionals and increase AFS participation at all levels. I also served as the Southern Division AFS Newsletter Editor that represents 15 states and am currently a member of the Virginia AFS Outreach Committee. My leadership in AFS has been recognized with several state and national awards.
Having realized my passion for science communication, I extended my outreach efforts beyond AFS programs and founded www.thetroutlook.com, a website specifically devoted to improving public access and understanding to information related to coldwater stream and trout ecology. Through weekly updates, I provide information about my research and introduce the readership to topical issues in fisheries conservation. This website has been viewed over 70,000 (side note- this number is getting closer to 100,000 now) times by an international audience, is regularly used as a teaching tool in K-12 schools, and has attracted attention from community groups and universities. Because of this media presence, within the last year I was invited to give nearly 20 seminars to several universities and to the Pennsylvania Council and local chapters of Trout Unlimited.
My passions for research, outreach, and education underlie my desire to pursue a career in academia. I believe that the persistence of natural resources will depend on inspired, well-trained scientists who can think creatively and critically to solve some of the world’s most pressing problems. I want to enable the next generation of problem solvers by fostering in them a life-long curiosity for ecological research. This is a goal I have already started realizing as the lead advisor for seven undergraduate students at Penn State and Susquehanna universities completing independent research projects or internships.
I may be too stubborn to stop wearing shorts, but there’s no question that summer has ended in Pennsylvania. Tomorrow I’ll be headed to Loyalsock for my first day of fall sampling, and the third-to-last sampling event of my PhD (crazy). It’s been one wild ride, and the last day I drive out of Loyalsock is going to be a bittersweet exit. But, I have a few months before I need to think about that.
What’s on my mind today is the feedback that I’ve gotten from my post last week on stocking. Great discussions, great questions, and hopefully a few people that thought twice about their positions on trout stocking. Generally speaking, the vibe I get from most people is that they do support stocking programs, just not in Class-A wild trout streams. Some even go as far as to advocate for the end of stocking in all streams that support wild trout, regardless of abundance.
There’s nothing wrong with these views. In fact, my own opinions are casted with shades of this logic. They present a compromise- potentially a stocking protocol that could allow for increased recreational opportunities while still protecting wild trout.
Notice I say “potentially”? In ecology, everything is connected. And, when we do one thing to one stream, we can’t be certain that it will or won’t impact the streams around it. That’s what makes natural resource management a game of knowledge and know-how, but sometimes also a lot of luck. Mother Nature can be finicky. We can do math, study the science, and prescribe a certain management protocol and get the same result 99 times. And then the 100th time it fails. Hopefully it’s a contained failure with minimal loss, but other times the damage cascades throughout the ecosystem causing damage at levels. Not often, but sometimes.
So, we can limit stocking. We can even put a moratorium on stocking Class-A streams, or any other stream that holds a special designation. But, how much damage control does that really do? Seriously, I’m asking- I don’t know the answer.
The uncertainty comes from the fact that fish move. A lot. Particularly large, stocked fish that are spooked by their new surroundings when they are plopped down into a stream for the first time. In our dataset, we found evidence of hatchery introgression and fish straight off the hatchery truck at sites that are several miles from the closest stocking location. And, we routinely find a pulse of very large fish moving into smaller tributaries in June- the same time when water temperatures in larger waters get too warm. I can’t say that these are definitely hatchery fish, but I would bet money on it (and on a grad student salary, that says a lot).
So, my post today is just a cautionary tale. To protect and conserve waters, we can’t keep thinking of streams as individual units. Effective restoration of one stream often requires action to be taken on surrounding streams and on the landscape. Likewise, the effects of stocking will extend beyond the streams that fish are put in. Not stocking Class-A streams would be a great success for native trout conservation. But, if there is a stocking location in the next adjacent tributary, then the successes could still be minimal.
As long as we are stocking trout somewhere, there will still be some chance for negative effects to native populations. That isn’t meant to be a rally call for the end to hatcheries. It’s meant to be a warning that the solution isn’t quite as easy as “stock here, not there.” How far hatchery fish can spread is not certain, and it is going to vary depending on a lot of factors. When determining stocking locations, we need to think beyond the immediate radius of the release location. We need to consider what streams are within a few hundreds yards, to maybe even as far as a few miles. Could those stream be influenced by hatchery trout?
This brings up a bigger point, and that is nature is too variable for a “one size fits all” approach to management. It’s probably not advisable to advocate for a single management strategy to be deployed across an state. We need more emphasis on adaptive management- on adjusting management protocols in response to changing demands from humans, shifts in climate, and loss or gain of habitat. We need to use all the data available to us and make decisions. If we suspect that a certain management action is threatening trout populations, then it needs to be looked at a little closer and sooner rather than later.
It’s a daunting task, and certainly easier said than done. But, aren’t our natural resources worth it?
I’m back! And, boy was my absence untimely. While I enjoyed soaking up the rays attending the annual meeting of the American Fisheries Society in Florida, I unfortunately missed the Pennsylvania Wild Trout Summit. The PA Fish and Boat Commission was quick to post presentations online, so I’ve been able to catch a few talks (including the one below by my advisor, Ty). But, I’ve also been reading some feedback from a few attendees and my takeaway is that the best talk wasn’t by a platform presenter- it was among members in the audience. One of the reasons I love studying trout is the passionate anglers and citizen scientists that are invested and devoted to wild trout conservation and restoration. There is no other angler base that is as informative and fun to interact with as you all, and I was sad to miss the opportunity.
My other observation is that there was some disappointment in what wasn’t discussed. Most notably, it seems a lot of people in attendance wanted to discuss the state’s trout stocking plans. I’m not surprised. Stocking is controversial and there will probably never be a stocking plan that makes everyone happy. But, I’m also encouraged. The public is trying to voice their opinions on this really complex problem, and, from what I’ve seen, seem to largely understand the delicate balance between the science of native fish conservation and the social dynamics of recreational fishing. It’s not an easy line to walk.
I’m also encouraged because it means there is interest in our current research beyond the scientific community. Our manuscript on native and hatchery fish interbreeding is nearing completion, and the results are getting closer to being released. Until then, I’ve been spending most of my days pouring over manuscripts published over the last 20+ years from other studies of hatchery-wild interbreeding and trying to summarize their findings. From this, I’ve already summarized the pros and cons to hatchery stocking, but I’ve left you in limbo the last two weeks. Overall, do hatcheries have more of a positive or negative effect on wild trout populations?
Before I answer that question, there are two caveats. First, I’m only discussing recreational stocking- or stocking done to temporarily increase population sizes to allow for increased angling opportunities. The potential pros and cons to conservation stocking are a bit different. Second, I am only focusing on the hard science. I’m not going to attempt to compare the social benefits of stocking with the impacts to native fish diversity. But, you should. Everyone should weigh the pros and cons and make their own informed decisions about stocking. It’s not my place to make the decision for you, but it is my job to present the science so that you can be informed. We know that stocking increases recreational opportunities and can be an economically profitable business, both of which valuable. Taking that into consideration, I have drawn a line in my mind where I think stocking is worthwhile and where it’s not. You need to find that line without someone telling you where they think you should put it.
So, after 20+ years of study, what do we know about the effect of hatchery stocking on wild trout populations?
So, where does that leave us? With a lot of uncertainty. Hatcheries can have negative effects on wild populations. But, not always. And, hatchery interbreeding can be high in stocked populations. But, not always. And, we know that there are long-term negative consequences of interbreeding. But, yet again, not always. We just don’t know.
Perhaps a more important question- where does that leave you in your thoughts on stocking?
Picking up where we left off last week, this week I’m going to flip the switch and talk about the potential negative consequences of stocking. I highly recommend that those who missed, or maybe just don’t remember, last week’s post start there before continuing. Some lingo and concepts may be a little fuzzy without the background information.
You didn’t press the back button, did you? (I don’t blame you, I wouldn’t either). So, here’s a quick refresher: wild trout populations have genes that are locally adapted to their native environments. This means that trout have genes that make them successful at life in their home stream, but their genes may not be great for surviving in another stream. However, not all fish in a stream can be identical clones of one another. There needs to be some level of genetic diversity in order for populations to survive disturbance and be able to adapt to future conditions. I call this the “eggs in many baskets” insurance policy. The genes that are best this year may not be the genes that are best next year, and so there needs to be high diversity so that at least some fish can survive and reproduce if conditions change in the future (if you’re a financial guru, this concept is very similar to having a diversified stock portfolio).
Easy, right? Well, here’s some of the ways that hatcheries can disrupt this balance. I’m focusing specifically on recreational stocking programs because conservation stocking programs have taken more precautions to avoid these potential pitfalls (though, they do sometimes still happen).
Ask and you shall receive! My recent posts have focused on the potential influence hatchery fish can have on wild populations, particularly if they starting reproducing with one another. With stocking a common, but often contentious, practice, I knew many people would be interested in our pending data analysis and results. But, I never thought it would get as much interest as it has. Even better, I’m getting some really great questions from many of you trying to wrap your head around the pros and cons of hatchery stocking.
Unfortunately, the manuscript I am in the process of writing will do very little to help clarify those questions. Heterozygosity, allelic richness, Hardy-Weinberg equilibrium, FST, genetic distance, bottlenecks …do these words mean much to you? No? That’s okay- they all refer to genetic measures that scientists look at to determine how an event (like stocking) is influencing a population. We know that certain events cause some of those numbers to go down, and other events will cause those numbers to go up. Describing how those genetic statistics have changed (or not) as a result of stocking is largely what I’ll be talking about in my manuscript. Not very reader friendly.
But, those statistics are the nitty gritty. Just like you don’t need to know how an engine works to drive a car, you don’t really need to know the exact genetic details to understand the pros and cons of stocking. But, understanding some basic genetics concepts and a little lingo will go a long way in helping tease apart why the potential effects of stocking on native populations aren’t so cut and dry. It’s also helpful to have this background knowledge when deciding whether you feel the risks of stocking are worth the rewards. So, for the next three weeks I’m going to flesh out the possible pros (this week) and cons (next week), and then round out the mini-series by summarizing the consensus among biologists as to how much stocking is affecting fish populations worldwide.
Where to start. Let’s first talk a little about why we have to think about genetics when assessing the effects of stocking. The brook trout of today are the product of millions of years of natural selection- genes that produce healthier fish and the most offspring are more likely to get passed on to the next generation, whereas genes that are associated with lower survival and reproduction eventually get removed from the population. Making things more complicated, the best genes for one population are unlikely to be the best genes for another population. This is called local adaptation- millions of years of natural selection have left fish from a given stream with genes that give them the best chance of survival in that stream (highlighted for extra emphasis). Local adaptation makes fish successful at living in one environment, but potentially not very successful if they are transferred into another environment.
Following that line of thought, it seems like fish should stay in their home stream to fine-tune local adaptation and increase survival. But, it’s not that simple (for starters, fish don’t choose to adapt, but that’s a story for another day). Streams are highly variable environments, and local conditions change faster than fish can adapt. So, stream fish populations need to put their eggs in more than one basket- they need some fish that have genes that are successful under certain conditions and other fish that are successful in other conditions. In other words, populations need a lot of genetic diversity. With increased genetic diversity there is increased survival and resiliency to changing conditions, but also increased potential for populations to be able to adapt to future stressors (like climate change).
A lot of things influence genetic diversity, but some of the biggest contributors are population size and population connectivity. Big populations that have a lot of fish moving into and out of them tend to have high genetic diversity. Historically, this is probably how many brook trout populations existed. But, times have changed. Population sizes have declined following natural disaster, disease, habitat loss, etc. And, many populations are now isolated by waterfalls, road crossings, and thermally unsuitable habitat. When populations get too low and too isolated, genetic diversity quickly erodes as fish start inbreeding and other genes get randomly removed from the population (a process known as genetic drift). For all of these reasons, one of the biggest priorities fisheries conservation managers have is to restore genetic diversity by increasing population size and connectivity.
Did you follow all that? No? That’s okay. Big picture- fish become genetically specialized to the local environment (local adaptation), which increases their survival. But, the population can’t become too specialized because it needs high genetic diversity in order to be withstand disturbance and have the potential to adapt to future conditions.
Okay, so where does stocking come into play?
First off, there are two basic forms of fish stocking. It’s important to keep them separated as we discuss the pros and cons of stocking because they are very different from one another and have their own benefits and drawbacks. The less common form is conservation stocking, where the goal is to increase population sizes and genetic diversity of critically threatened or endangered fish or reintroduce a species to its native habitat after restoration. In conservation stocking, the fish populations are generally not harvested, and stocking is used to prevent future population declines and extinction.
Conservation stocking is very tricky business. The genetics of every individual used for reproduction are carefully considered so that the stocked population is locally adapted to the wild environment, thus giving fish the best chance of surviving and reproducing. This also helps avoid outbreeding depression - when a native, locally adapted fish spawns with stocked fish that is not locally adapted and the offspring have lower survival and reproduction. Outbreeding depression has the potential to cause rapid population declines as each generation continues to have lower and lower survival and reproduction. To avoid potential effects of outbreeding depression, fish used in conservation stocking are often brought in directly from the wild and only kept in captivity for a few generations, thus minimizing genetic differences between wild and stocked populations.
Now, contrast that with recreational stocking. Recreational stocking, especially for trout, is by far the most common. The goal here is to stock as many large fish as possible in order to increase angler satisfaction. Genetics are considered, but mostly as a means to grow bigger fish, faster. In other words, fish used for recreational stocking have been artificially selected. As opposed to natural selection (where the environment picks the best genes), in artificial selection humans are the ones deciding which genes are best. It takes many years for humans to artificially select the genes that will make a population grow large and fast. But, once that goal is achieved, wild fish are no longer brought into the hatchery because wild fish will not grow as large and as fast as their artificially selected counterparts. In fact, it’s been over 100 years since the last wild fish has been introduced into many hatcheries used for recreational stocking. Because of this, fish used in recreationally stocking are genetically incompatible with the wild environment, and have lower survival and reproduction once released.
So, what are the pros of stocking?
So, yes, stocking can have positive influences on native populations. But, I’ve already hinted a few times that most stocking and hatchery practices are unable to realize some of these potential benefits. But, tune in next week for a more detailed discussion about the possible negative consequences of stocking.
I wrote last week of the two types of grad student vacations, conferences and field work. But, there’s another holiday that’s even rarer (at least for me) and merits even more celebration. I’m talking about your advisor’s vacation week, otherwise known as Grad Student Independence Week.
Truth be told, my advisor’s whereabouts don’t really influence my work ethic. For the time being, I’m working at my own self-defined pace (cross my fingers I can keep it that way). But, the closer we get to the beginning of the semester, the more sparse the office gets. With no one to pester during the day, why bother going in?
So, I didn’t. I slept in a little later (which for me is 6am), enjoyed coffee on my patio, and had one main goal: start working on the hatchery-wild hybridization manuscript. Data analysis is still on going, but at this point I know what the results are going to say. There’s no need to wait for the final numbers to crunch to start the long process of preparing the work for publication.
When I was an undergrad, I always thought that scientific publications were the works of brilliant scientists who wrote the equivalent of Shakespearian prose. I never thought I’d be smart enough to accomplish a similar feat. I actually still think that, except I’ve somehow been let into that elite crowd of published scientists seven times now. It still hard to believe I’ve reached the point in my career where I am the authority on a topic- someone out there is reading my manuscript and thinking I am the brilliant scientist. Crazy.
One thing I have learned along the way is that regardless of how smart you are, how great your research is, or how well you write, all manuscripts start in the same place. With a blank Word document that just stares at you. For me, it’s probably the single most intimidating and frustrating part of the publication process. Literally anything I put down “on paper” would represent an improvement over the blank page, but I just sit there for hours- staring, erasing, and getting more frustrated.
There’s all sorts of advice out there about how to be the best, most efficient writer- outline your ideas, write 30 minutes every day, discuss your paper beforehand, etc.- and I defy every single recommendation. That long, frustrating, fight with the blank page is just part of my process, and I need to work through before I can write something worth saving. And, the fight needs to be long and uninterrupted. Not a great task for tackling at the office where distractions are imminent, but a perfect job for celebrating my Grad Student Independence Week at home.
I actually only got one full day at home, but it was enough to win the battle and get a solid start on the manuscript. Time to save it, back it up, and not look at it for at least a few days. In the meantime, I go back to square one- read published manuscripts that I know are important for my study and that I will cite in my own publication to support why our study was needed and to add credibility to the results we found.
As I’ve said before, there aren’t a lot of studies on hatchery-wild interbreeding in brook trout. But, I did find one by Andrew Harbicht and colleagues (see below for a link to the manuscript) that looked at how the probability that hatchery trout will breed with wild trout changes depending on the environment. I’m still not releasing the result of our analysis, but studies like this are important regardless of what we find. Whether we find a high degree of interbreeding or not much at all, we need to know WHY we are getting that result. And, it makes sense that environmental conditions influence how much hatchery trout breed with their wild counterparts.
The study was conducted on several lakes in Algonquin Provincial Park in Ontario, Canada, of which some were never stocked with hatchery brook trout, and others had historic stocking that had been stopped 10+ years prior to their study. Immediately, you’ll notice there are some differences between their study and ours: we work on streams, and in areas that are currently being stocked with high densities of fish. Nevertheless, their results are important to keep in mind as we move forward. Most importantly, they found:
So, why is this study important for us? For starters, streams often support lower populations of brook trout than lakes, making us nervous that interbreeding may be more prevalent in streams than lakes- particularly, again, because stocking in our systems is frequent and on going. Our streams also have a wide range accessibility, pH, and other environmental variables (e.g., gradient and temperature) that influence population sizes and competition. Big picture, this study just shows us that introgression isn’t an all or nothing phenomena. Location matters a whole lot, and our results can’t be taken as the definitive response of trout to stocking.
But, all of this presumes that we are finding interbreeding. Which I’m not saying we are. I’m also not saying we aren’t. You’ll just have to stay tuned.
*Note: Content in this post is my own and may not reflect the opinion of the manuscripts' authors or the agencies they represent. I encourage you to read the manuscript, found here, so you can contribute to the discussion.
In grad school there are two types of “vacations.” There are conferences, which you hope are in desirable cities that you can explore at night after you’ve turned your brain to mush hearing about cool research and talking to collaborators all day. And then there’s volunteer field work, where you are probably working harder than you would had you not gone on “vacation,” but are just happy to be seeing a different system and learning about a different project for a little bit.
Right now, I’m on the later form of vacation. I traveled six hours south to my alma mater in Ashland, Virginia to help put another year of Mechumps Creek post-restoration monitoring into the books. Some of you may recall Mechumps Creek from my post last year, where I described the need to rebuild this urban stream to restore and protect habitat from stormwater runoff. And, no, there are no trout in central Virginia. But, had it not been for a class on stream restoration featuring this tiny creek, I would have never pursued a career in fisheries. So, Mechumps Creek will always hold a special place in my heart and I’ll gladly “vacation” here anytime (but ask me again when vacation loses those quotation marks).
But, this year’s sampling was a bit different than past. Per the usual, we picked the hottest day of the year for fieldwork. With heat indices once again soaring to 110°F, I swear the Farmer’s Almanac could start using us for their long-term forecasts. And, there was no lack of poison ivy, dense thorns, and interesting animals. As it turns out, beavers don’t much appreciate 250 volts rolling through bodies.
The difference this year was that we got to do twice the work. Lucky us! Normally, our sampling is focused on one section of stream that was restored in 2010 and is now being monitored to determine the long-term response of fish populations (among other things) to restoration. Though there are still a few years left in monitoring, restoration of the first section went so well that a grant was recently received to restore the next reach located just downstream. Woohoo! But, before restoration can start, there needs to be baseline measurements of what the stream and fish community look like now so that later they can determine if restoration was successful. So, after sampling the post-restoration section, we headed downstream to complete the pre-restoration assessment of the fish community.
I was part of pre-restoration sampling of the original section seven years ago, but I’ve long forgotten what fish we caught way back then. So, it was interesting to see, back-to-back, the difference in habitat and fish diversity between pre- and post-restoration sites. Post-restoration, the stream is, on average, only a couple feet wide with maybe five pools in the entire 1,200-foot section, the deepest of which about three feet. Compare that to the pre-restoration reach, which was much wider, much siltier, and was pool after pool, with some too deep to wade through.
On the surface, the shift from many deep pools to mostly small riffles with restoration may seem a little undesirable, especially for all you trout enthusiasts out there. After all, big fish need big pools. But, not all streams are created equal, and management goals are not the same for all streams. While we may want to increase pool size and depth in a coldwater trout stream, Mechumps Creek is a tiny, warmwater system. We don’t necessarily care about the size structure of fish because no one is hoping to catch a citation sunfish out of Mechumps Creek. But, in order to preserve the integrity of large creeks and rivers downstream, we do care how well the ecosystem is functioning in Mechumps Creek. And, from a fish perspective, an indication of ecosystem function is how many different species are present (species richness) and how abundant each species is (species evenness). In short, we not only want to see many different species, we also want to see that individuals of each species are equally common throughout the stream as opposed to only one or two species dominating.
How do you increase both richness and evenness? By increasing habitat complexity and diversity- in this case reducing the number of deep pools and increasing the number of riffles and runs to provide habitat for many species that prefer many different types of habitat. This is one of the main goals of stream restoration that is best accomplished by reshaping the existing channel and reducing future streambank erosion (how this is accomplished is feat of skilled engineering, of which I won’t get into the details here).
So far, it seems past restoration efforts at Mechumps Creek have accomplished this goal. This year, while there were many species in the downstream, pre-restoration site (i.e., moderate richness), many of them were fairly rare (low evenness). Most of the fish we caught in the pre-restoration site this year were catfish, sunfish, and mudminnows, all species that we see most commonly in muddy backwaters with low oxygen(i.e,, the habitat that was most prevalent).
In the post-restoration site, we found many more species (higher richness) and improved evenness. There were fewer catfish and mudminnows, and far more darters, dace, and chubs, species that all prefer habitats with more moving water and less silt. So, we can tell from the difference between the fish communities that habitat restoration has long-term improvements to species richness and ecosystem function of Mechumps Creek. Hence the reason for moving on to phase two!
This year wasn’t just special because of the ability to do pre- and post-restoration comparisons. Because we’ve focused all of our attention on the post-restoration reach the last few years, I hadn’t visited the pre-restoration reach in about ten years, back when I was a college freshman hoping to pursue a career in surgery. So much has changed since then, but walking through the stream was like rewinding the clock. Trees we used for survey benchmarks still stood strong, sandbars we had group meetings on had only grown larger, and our little foot paths through the dense brush still seemed completely intact. I can remember many cold, rainy afternoons spent roaming around that stream with my comrades, Sonni and Arba, naïve to the future to come (nor knowing what I even wanted the future to hold), but having the time of my life trying to learn about stream ecology.
Now, here I am, ten years later. I’m turning the corner on my Ph.D., still naïve, but still having fun learning stream ecology. Surveying Mechumps Creek this year, I’m reminded of the leap of faith I took in deciding to pursue a career in Ecology. I won’t lie, I sometimes wonder what might have happened if I didn’t ____ (fill in the blank with any of about 100 serendipitous decisions that got me where I am today) and I had pursued medicine. But, I think back to the experiences I’ve had over the last ten years, the utterly ridiculous things I still find interesting about fish, and the curiosity I still have for research, and there’s no doubt I made the right call.
I’m excited for this next phase of restoration- the restoration project I pitched to Ashland Town Council ten years ago and worked on tirelessly my entire first year of college is finally being realized. But, it’s also bittersweet. The little ecosystem that taught me a love for field ecology was practically unchanged. But, in just a few months, it will all get ripped out with a few swings from the backhoe. It’s a little like renovating your childhood home. I now it needs restoration, but some good memories and a lifetime worth of professional gratitude are tied up in those ugly, eroding banks.
So, I bid farewell to pre-restoration Mechumps Creek. But, the story doesn’t stop here. I’ll go back next year to visit the new and improved stream, meet the new tenants, and start the next chapter of Mechumps Creek.