What fish want

What do fish want? I thought I would try to focus on a seasonally-appropriate question, but also one that I spend a lot of time these days pondering. You might think that it would be simple to figure out what motivates a fish—after all, they probably aren’t influenced by the complex emotions that drive people. But unfortunately, we can’t just ask them (I have often wished for just one hour as a fish—I would learn… and publish… so much!).

In general, animal behavior is driven by a balance between the drive to maintain/gain energy stores, survive, and ultimately reproduce. So when asking why a fish chooses to inhabit a particular area of the river, we start by looking at the environmental factors (such as water temperature and shelter from potential predators) that might be influencing its behavior. In my research, I’m interested in what environmental factors are influencing juvenile steelhead behavior surrounding coolwater refugia (areas that are cooler than the main river, often because of an incoming cold creek). What causes fish to use coolwater refuges? And when the river is really hot, what causes fish to leave the refuge? In asking these questions, I’m hoping to gain an understanding of when these refugia areas are most important to fish.

Juvenile steelhead being measured

A heat image of a coolwater refugia area on the Klamath River (Image from U.S. Bureau of Rec)

Taking a step back… many rivers are getting hotter, both because of climate change (influence of higher air temperatures), and land use practices such as logging and agriculture. Logging the riparian area next to a stream reduces shading,  causing the water to heat up. Irrigation can lead to hotter water temperatures if water is diverted into shallow, slow-flowing irrigation ditches, then returned to the river. The Klamath River in northern California, where I do my research, can reach 80°F in the summer, which feels like bathwater. On cool mornings I would sometimes even get into the water to warm up.

Salmon are a coldwater fish, and prefer a temperature range of about 10-18°C (50-65°F). This means that during the summer, when the river temperatures reach 80°F, they are under serious thermal stress—the high temperatures increase their metabolism, so they struggle to maintain weight. As a result, fish will seek out areas in the river that are cooler, such as areas where tributaries flow into the river (i.e. thermal refugia). You can sometimes see hundreds of juvenile salmon packed into small coolwater refuges. However, fish sometimes leave the coolwater areas, even when the river is hot. Why? This question forms the root of my research.

Juvenile steelhead in a coolwater refugia area

I’m hypothesizing that it’s a trade-off between water temperature and the need to find sufficient food. While the fish gain a thermal benefit by hanging out in the cooler water, the high densities of fish suggest that there may be competition for food, forcing fish to leave for brief periods in search of prey.

To put this dilemma in a human perspective, imagine that it's 120°F outside, and you are in a nice air-conditioned house… with no food. You have the choice to go out and pick some food from the garden, or just stay inside and feel hungry. It’s a trade-off! At what point do you decide to leave? Now imagine that your body temperature changes to that of the outside temperature—so as soon as you walk out the door, your temperature begins to rise. This is what happens for fish, since they are poikilotherms—cold-blooded animals that do not stay in a temperature-constant environment, so their internal temperature varies over a wide range. While they are adapted to function over a certain range of temperatures, water temperatures may be rising more quickly than fish can adapt, leaving them with a shrinking amount of available habitat.

In order to understand when and where coolwater refugia are most important, we need to figure out what specific environmental factors are driving fish’s decisions to enter and leave refugia. To do this, I conducted behavioral field studies on juvenile steelhead at coolwater refugia sites on the Klamath River for the past 3 summers. I put radio tags into steelhead (see video below), and was able to track their movement and body temperature (pretty cool!) over time. So far, I’ve found some interesting effects of water temperature dynamics on the likelihood of fish using thermal refugia… stay tuned! (And to learn more about how I’m researching this, visit my website!)

Put in a larger (non-fishy) context, refugia habitats such as this will become increasingly important as the climate continues to change. Whether it’s a range shift upwards onto mountaintops for a high altitude terrestrial species, or a fish seeking out cooler water, understanding how animals use refugia and when they are crucial to their survival will be an important aspect of preserving some species.

And now, if you’ve made it this far, enjoy the holidays! I, for one, will be enjoying a taste of the fruits of my labor.

The problem of truth

I read an interesting (and rather infuriating) opinion piece on salmon in the Gridley Herald a few weeks ago, claiming that salmon populations on the Klamath River in northern California are doing just fine. Gridley is a small town in the Central Valley south of Chico. The author, James Finses, based his claim on one good year of salmon returns, as well as bashing the groups he disagrees with (more details below). While making me writhe internally, this piece also got me thinking once again about denial, and how we shape truth.

The problem is that people have different versions of the truth. Scientists version of truth takes the form of testable hypotheses that are “proved” (or fail to be rejected, if you'd prefer), or quantitative models, but that’s not how people work. People, in general, are most likely to believe what they see (first-hand data), and this is tempered by what they want to see (which is where denial comes in). Since I happen to be watching football right now (don’t be too shocked…I was coaxed to the bar by my husband), the analogy that comes to mind is if a team does well the three times in a row you happen to watch them, you’re more likely to believe that they’re good rather than the long-term statistics that tell you they’re terrible. In short, we’re more inclined to believe what we see right in front of us (and especially when we like what we see), rather than trying to put things in the larger context… especially when it’s inconvenient or displeasing to do so. Thus, we can easily create a convenient reality, when so inclined.

This problem of truth extends to opinions surrounding salmon fisheries management. There’s lots of data and scientific papers showing that our salmon populations have crashed in the past century, but there is also tremendous economic, cultural, and social pressure to keep fishing. This creates a situation where there are a lot of people with different opinions and goals searching for a slippery truth (i.e. how do we best restore/maintain salmon populations).

Restoring salmon populations is not an easy or straightforward task, and can demand innovative and sometimes unpopular (with some) approaches, such as dam removal, fishing restrictions, or expensive fish ladders, all of which can inspire heated controversy. This is the case on the Klamath River in northern California where I do my research, and where there are 4 dam removals planned for 2020 in order to help restore fish populations (including ESA-listed Coho). On the Klamath, there are many interest groups who care about both fish and water flows, including fishermen, native tribes, rafting companies, farmers, and fiery locals.

Returning Chinook salmon on the Klamath River

And so when record numbers (~380,000) of Chinook salmon were projected to return to the Klamath River this year — a run size close to historical returns for fall Chinook — it is no surprise that there were people, including James Finses of Gridley CA, eager to jump at the opportunity to claim that salmon populations are doing just fine. In his opinion piece, Finses is quick to point out that the fish are returning despite the fact that we still have dams, and that “the dirty, unscientific data brought forth by the tribes, enviros and other whacko groups was wrong all the time.” The problem with Finses’ argument that one good year of salmon returns means that salmon populations are fine is that salmon populations are incredibly variable year to year, and the success of a particular cohort depends on numerous conditions including favorable river temperatures and ocean conditions (abundant plankton and low predator numbers). In the end, he states that “the salmon are back in record numbers with all the dams to help them.” I find this last sentence particularly interesting, since it reflects the desire to not just disprove undesirable truths, but to use this small piece of evidence (one year of good salmon returns) to reshape the truth (i.e. dams must be helping the fish). Whether Finses actually believes this statement or not, the fact remains that humans are susceptible to incredible willful short-sightedness when it suits us. So in questions relating to fisheries management, the truth very quickly becomes a slippery shadow, swathed in politics and emotion, often taking different forms for different people.

Fish ladder on John Day River dam

My husband came across another example of this truth-shaping during his research on dam removal, when talking to a local about fish ladders. Fish ladders are structures built into some dams that allow for anadromous fish migration – they are usually a series of small steps and pools with sufficient flow to attract fish to them. While having fish ladders is better than providing no fish passage at all, they are only somewhat successful; some problems include increased predation (predators, such as bass or birds, can sit at the end of the fish ladder, picking off a tasty meal as the salmon funnel through), and possible delay and additional energy demand on the fish (especially as they pool up at the bottom, awaiting their turn in the limited space). However, having a fish ladder is somewhat of a band-aid fix, and can make it seem like the fish are doing fine, especially since it often causes the fish to pool up, so that visually it appears that there are a lot of fish. As the local remarked to my husband, ‘the fish are just hanging out below the dam, “taking their time.”’

So will one good year of salmon returns make us forget those that have come before? As scientists, the answer is no. But as humans, we are susceptible to our emotions and personal biases.

Ecological Restoration: Are we in denial?

“I think that if it weren't for denial, I wouldn't be a comedian because to be a comedian you have to go on stage those first few years and bomb. And then walk off stage and think, that went great. Because otherwise you'd never get on stage the next night. You would just think, human beings don't like me. But sometimes denial can kill you.” –Comedian Mike Birbiglia 

Are we in denial about climate change and the state of our earth? Certainly some of this country is... although luckily, on Nov. 6^th the country voted to support the environment (as well as many other important things). But even for those of us who do believe in climate change, and even try to change our day to day actions to help alleviate the problem, a question that haunts me is, “is this enough?” Is biking to work every day and eating organic and buying carbon offsets for travel (and generally acting like we are in Portlandia) really enough? And are current ecological restoration projects and conservation efforts sufficient?

As I was mulling over how to frame this question into a constructive blog post—since it is so easy to debate round in circles on this question, to no avail—I came across a recent paper by one of my advisors that addressed an interesting angle on this question. The paper, “Ecological restoration and enabling behavior: a new metaphorical lens?” by KD Moore & JW Moore, examines how we currently view ecological restoration, and how that perspective might be shaping both our behavior and the way we go about restoration. When we discuss ecological restoration, we usually assume that we are talking about something inherently positive. The paper makes the point that the language of ecological restoration is that of “healing and repairing,” which carries a positive connotation. Who wouldn’t you want to help the environment by restoring it (given unlimited money)?

However, as this paper discusses, there are certain problems with our current approach to restoration. Many restoration projects are not followed by sufficient monitoring (the case with many dam removals), so we are left to wonder how effective the restoration actually was. In addition, Moore & Moore cite several examples where post-restoration monitoring has shown that “restoration effectiveness is questionable.” (This is not to say all projects are ineffective, but rather that we should not assume the effectiveness of our restoration projects).

But besides the problem of monitoring, there is the question of whether we are enabling our energy-hungry habits by convincing ourselves that our restoration projects will take care of the problem. The paper draws an interesting metaphor for this scenario using the co-dependency of addicts (for instance, an alcoholic) and their enablers (e.g. someone who keeps paying the alcoholic’s bills). In this case, Americans are addicted to cheap, abundant energy (which comes at the cost of environmental degradation), and the enablers are the environmental restorationists, who make us feel like we are healing the environment, and who are secured a job in the wake of the destruction. Perhaps this view is too cynical—surely restoration specialists are not voting for Romney or buying SUVs just to ensure their own job security.

But, as the authors explain, we can draw an interesting lesson from this perspective; we can use this “metaphoric lens” to think about whether restoration activities have “opportunity costs”—in other words, are we using funds for restoration that could be better put towards getting rid of the cause of the degradation? We can also use this lens to examine whether these restoration activities “conceal the truth” from ourselves—we want to believe that we can destroy a habitat, extract what we need, and then restore it back to its starting state. But this is rarely the case. Yet we often move forward with restoration projects as if this were true.

 

I am not arguing, by any means, that we should discontinue ecological restoration. Rather, it should be a stepping stone to whatever is next. However, we know from basic physics that systems in motion have momentum, and the momentum to keep going in the direction of motion can be very strong, not to mention easier than applying force to the system to change (yes, I love physics… I even minored in it in college). In other words, we need to work to change our current habits, and along the way, we need to continually evaluate our actions. We do not want to be the ostrich, head stuck in the sand, patting ourselves on the back at all our good environmental work, and meanwhile drowning in the rising ocean.

As the comedian Mike Birbiglia says, “sometimes denial can kill you.” Or, in this case, probably our grandchildren.

So we need to rid ourselves of denial, and ask, does despair begin when denial ends? Or is that when true hope and action are born, out of the “power of outrage and… the wisdom of grief”*?

*Moore & Moore

Bass and salmon: who’s for dinner?

I went to an interesting lecture this week at the University of Washington Fisheries department on the potential effects of climate change on the interactions between Chinook salmon and smallmouth bass. 

Smallmouth bass

Juvenile Chinook salmon

Smallmouth bass are native to the Northeast and upper Midwest, but like many other fish species, they were spread across the United States by avid fishermen during the 20^th century. One method of spreading bass was to put them in large milk containers on trans-continental trains, and then stop and dump fish in every body of water they passed along the way. By the second half of the 20^th century, stocking fish became even easier, with the invention of planes.

Fish being released from a plane to stock a lake for fishing

As with many of the things we did to nature in the 1900s, we are now beginning to understand the consequences of planting bass. In western rivers, one major impact of non-native bass on Pacific salmon is predation. Bass eat juvenile salmon, and in rivers where they co-occur, they form a predatory gauntlet for the juvenile salmon migrating out to the ocean each year. As one fishing website declares, “smallmouth bass are aggressive freshwater fish that will readily engulf nearly anything that they can fit in their mouths.” And juvenile Chinook certainly fit that description.

The fact that Pacific salmon populations have crashed over the past half century as a result of climate change (hotter river temperatures), freshwater habitat loss (dams etc.), and overfishing, is well-known. There are lots of studies showing that rising river temperatures negatively affect salmon, but what I found really interesting about this lecture was the discussion of how climate change (in the form of hotter rivers) could affect the interaction between bass and juvenile Chinook salmon. Salmon are cold-water fish and can only tolerate water up to about 75F, so as rivers warm, juvenile salmon are forced higher up into watersheds to find suitably cold water to rear in. At the same time, small-mouth bass are limited in the opposite direction – if the water is too cold, they can’t spawn. So as rivers warm, they are able to move further and further up watersheds. In the John Day River in Oregon, smallmouth bass and juvenile Chinook rearing habitat now overlap. This range shift and overlapping habitat lead to new questions: will bass presence negatively affect juvenile salmon in other ways than direct predation? It’s no longer just a predatory gauntlet, a one-time-only deal that the juvenile Chinook have to face as they out-migrate. Now their daily interactions and behavior, and possibly their growth potential, could change as a result of the encroaching bass. On a much larger scale, it is these kind of unforeseen effects of climate change that make it so hard to predict.