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The "Red Line"

Updated: Mar 1, 2021

On angling pressure, water temperatures, monitoring, and stewardship.

2020 was a tumultuous year, for a variety of reasons notwithstanding a global pandemic. But within the context of the Upper Madison river, recreation management and the often-contentious, years long debate on how to proceed finally ended (for now) with the state publication of new rules (which begin to take effect in 2022). Those new rules can be found HERE. Prompting this discussion was an overall rise in popularity of river recreation (even prior to the surge of 2020) in the face of changing global climatic conditions (for the worse) and the concern that the combination of these two events could have on a widely cherished and robust fisheries resource currently boasted by the Upper Madison river and the experience of users.

The resulting rules will have marginal influence on the overall surge in recreational use pressure, as they completely omit addressing the burgeoning public use sector (over 85% of annual use) and instead solely restrict commercial use (less than 15% of annual use).

We heard throughout the debate about a feared “red line” with regards to a dreaded decline in fisheries health due to angling pressure. The thought being, though all indications are the fishery is robust and strong right now, we should start managing recreational use now before we notice declines in the health of the fishery. That, if we wait for signs of decline, by then it may be too late.

The assumption was, there has to be a point at which angling use impacts the fishery, even if it’s virtually all catch and release. But where is this red line, what does it look like, and how does is correlate to angling pressure? How does pressure affect fish? How much pressure is acceptable and unacceptable to the resource? I was disappointed to see the lack of science and these questions on angling pressure in a warming climate go largely unaddressed during the rules process.

Although this idea may seem simple (we like to catch fish, fish don’t like to be caught, and they sometimes respond poorly), there are a variety of dynamics that play a role in determining how fish respond. Some more obvious than others. In the context of a rapidly warming climate and a rising popularity in angling, however, there is one factor that seems very tangible and easily understood insofar as its role in how well fish respond to pressure: water quality and temperature. Water is everything to our fish and our sport. We have gauges on the Upper Madison for flows, stage, and water temperature, but we have nothing (that I’m aware of) in the vein of widely distributed or available data on water quality (e.g., nitrogen etc). We need this information desperately given the context of a rapidly changing climate. Instead of making assumptions one way or the other, data collection will help us make informed decisions. And certainly, we need to do better as a nation to reduce non-point source pollution and other behaviors that negatively influence water quality, quantity, and temperature. But let’s start with what we do have for data on the Upper Madison. Water temperature monitoring data.

Within the topic of water temperature and its importance to how resilient fish are to being angled, there are many complexities. For example, what are the lethal ranges of temperature for various species of salmonids? How does duration of lethal range of temperature impact mortality? Do cycling cooler temps help buffer the effect of the lethal range?

In response to changes in stream abiotic conditions as a function of climate change and high angler use during summer months, Montana Fish, Wildlife & Parks established a drought fishing closure policy (DFCP). The policy states angling closures are warranted for waters containing salmonids (excluding bull trout) when flows are at the 95% monthly exceedance level (1-in-20-year low flows); OR daily maximum water temperature reaches or exceeds 73°F for at least some period of time for three consecutive days. Closure options include time-of-day closures where angling is prohibited from 1400 until 2400 hours, and full closures where angling is prohibited at any time until reopening criteria have been met. Closed waters are considered for reopening when maximum daily water temperatures do not exceed 70°F for three consecutive days. The DFCP was designed to protect fisheries from the effects of angling during periods of high-water temperature and low discharge. The maximum water temperature threshold in the DFCP was based on biological opinion and a review of the effects of varying water temperature regimes on salmonids in a study by the USEPA in 1999 titled: “A review and synthesis of effects of alterations to the water temperature regime on freshwater life stages of salmonids, with special reference to Chinook salmon.

FWP also suggests that voluntary restrictions may be recommended before threshold levels are reached and that some waters will not reach the established threshold levels but may require action to protect the fisheries anyway. And lastly, other waters may reach threshold levels but may not warrant mandatory fishing closure because of site-specific conditions such as self-regulating angling pressure or success of voluntary restrictions. Indeed, some are already voluntarily restricting themselves like the Big Hole Lodge on the Big Hole River here in Montana.

While we have a substantial shortage of information currently available on how fish respond to angling pressure on the Upper Madison (virtually nothing) it turns out we do have surprisingly relevant data on the matter, at least regionally. A study in 2010 titled “Effects of Catch-and-Release Angling on Salmonids at Elevated Water Temperatures” (hereafter referred to as the “2010 study” found HERE) sheds important light onto the matter. Focusing on two proximate streams regionally to the Upper Madison (Smith River and Gallatin River), the study was co-authored by Montana FWP Region 3 Biologist Travis Horton. In the absence of Upper Madison river specific data on the topic of angling pressure, which we desperately need if we are to make meaningfully informed decisions on recreation management, this data is very useful and relevant when examining water temperature measurements on the Upper Madison and how those measurements look when viewed through the lens of lethal ranges for trout and potential risk as it relates to angling pressure.

As was discovered in the 2010 study on the Gallatin and Smith rivers, no mortality for any species due to pressure occurred in either river when daily maximum water temperatures were less than 68°F. That’s pretty incredible. The authors themselves were also surprised by that. When daily maximum temps rose above that magical number, mortality gradually began to occur.

Currently, on the Upper Madison (for this discussion, Hebgen Dam to Ennis Lake), we have 3 gauges which provide real time data on water temperature. The first is below Hebgen Dam itself. It can be found HERE. Obviously, being directly below a bottom release dam, the water temperature recordings here are consistently relatively cool. Roughly 17 miles downstream is the Kirby Gauge near the West Fork Madison. That gauge can be found HERE. It isn’t for another 40 miles downriver that we have our next permanently available water monitoring station in Ennis (temperature is not available at the Varney gauge). And, as we know, water temperatures generally increase in daily maximums as you lose elevation and especially as you get further from dam sources. The Ennis gauge is relatively new (started in 2017, with occasional offline absences in data), so there isn’t much historical data available. It’s operated by Northwest Energies in cooperation with Montana FWP. It can be found HERE. I like this gauge the best. One of the reasons is because it’s the lowest available gauge on the Upper Madison. Meaning, it provides insight to water temperature in the most likely reach of river where water temperatures will consistently be highest. That is, generally speaking water is warmer near Ennis than near Hebgen. It also shows that the Upper Madison near Ennis behaves more similarly to freestone streams than the tailwater that it technically is. Having a gauge here helps us understand maximum daily water temps on the Upper Madison more clearly. Good data! Now that we’re armed with data and relevant thresholds to keep in mind, let’s see what the 2010 study showed, then compare it to what we’re observing on the Upper Madison.

In the 2010 study, the primary objective was to measure the catch-and-release mortality of rainbow trout, brown trout, and mountain whitefish in three water temperature regimes, specifically, when daily maximum water temperatures were cool (<68°F), warm (71.6–73.2°F), and hot (73.4°F). I won’t go into the methods used here, but if you’re curious the study design is pretty interesting. There are also many other variables considered in the study worth reading about for a fuller understanding of the context.

As it turns out, each of the three common species of fish caught on the Upper Madison (rainbow trout, brown trout, and mountain whitefish) exhibit different thermal tolerances. And thus, exhibit different sensitivities to being stressed (i.e., caught). Most sensitive are mountain whitefish, least sensitive are brown trout, and in the middle are rainbow trout, according to this and other studies.

Five hundred and twenty-one fish were angled in the Gallatin River during 16 angling days, and 687 fish were angled in the Smith River during 14 angling days. Mortality of rainbow trout differed significantly among water-temperature treatments in the Gallatin River and Smith River. Mortality of rainbow trout was greater in the hot (16%) than in the cool treatment (0%) in the Gallatin River. In the Smith River, mortality was greater in the hot (9%) and warm (8%) treatments than in the cool treatment (0%). Mortality differed significantly among water temperature treatments for brown trout in the Smith River. Mortality of brown trout angled in the hot treatment (4%) was greater than in the cool treatment (0%). Mountain whitefish mortality differed significantly in the Smith River. Mortality of mountain whitefish angled in the hot (28%) and warm treatments (20%) was greater than in the cool treatment (0%). The majority (>76%) of rainbow trout, brown trout, and mountain whitefish mortality occurred within 48 h in both rivers.

As mentioned earlier, zero mortality was observed among all three species in the cool treatment when caught by anglers (<68°F). Furthermore, although water temperature peaked near 80°F in the hot treatments, mean water temperature was near 68°F implying they were also exposed to longer periods of cooler water temperatures. Longer durations in cooler water temperatures allow fish to “repair” physiological damage, thus potentially reducing catch-and-release angling mortality. So, while it’s important to watch maximum daily water temperatures, it’s also important to keep an eye on how cool water temps get for how long. For relatively high-altitude streams like the Upper Madison, which sees overnight air temperature lows swing dramatically even in summer, this could be a significant protector against reaching lethal range water temperatures for long durations. However, with the predicted increase in summer temperatures associated with global climate change it is reasonable to expect that the duration of daily cool temperature periods will decrease. The decrease in time suitable for recovery will certainly influence all salmonids.

Let’s take a look at 2020 data at the Ennis gauge on the warmest recorded water temperature day of the year – July 27th. July 27 began with a water temp of 66.1°F at midnight. By 0730 hrs it had reached its low point for the day at 61.6°F with the typical lagging response to overnight low air temperatures. It peaked at 73.4°F at 1700 hrs and ended the day at 66.6°F at midnight that evening. Using the information from the 2010 study, and the 68°F threshold for 0% mortality, the Ennis gauge on the warmest water temperature day of the season showed readings above this threshold for nearly 9 hours from 1300 hrs to 2145 hrs.

Here’s the graph:

On that same day, let’s look at the Kirby gauge. Here’s the graph:

You can see the effect of elevation and closer proximity to the dam have, among other variables, on reducing the impact of warm weather on water temperatures. Water temperatures here only exceeded 70°F for a few hours before plummeting back down to under 57°F on July 28th!

Lastly, what was water like coming out of Hebgen Dam on the warmest water temperature day of the season in 2020? Here’s the graph:

Coming out of the bottom of Hebgen, water temperatures reached a high of 61.3°F on July 27. By the time that water reaches Ennis 50 something miles later it warms nearly 12 degrees. Is this a lot compared to other streams? A cursory glance at similar distances on the Yellowstone suggest that it is, at least compared to that stream– a much deeper and volumous river. So, is a wide shallow river like the Upper Madison predisposed to higher risk of lethal water temperatures for salmonids? I don’t know, but it’s an interesting question.

And let’s take a look at the entire summer of 2020 (July 1-September 1) at the Ennis gauge where maximum daily water temperatures are always higher than the other gauges.

Here’s the graph:

According to the data there were 17 days in 2020 where the maximum daily water temperature exceeded 70°F. Is that a lot? Not many? Is that number trending in either direction compared to previous years? We don’t know, as 2020 was the first year of complete data at the Ennis gauge since its launch in 2017. However, criteria were not met for the Montana FWP closure policy (73°F for at least some period of time for three consecutive days). In fact, the water temperatures at the Ennis gauge hit the critical 73°F mark only once in 2020, for 9 hours. Most every one of those 17 days where maximum daily temperatures rose above 70°F, the temp hit the 70°F by 2 PM. But interestingly, even on each of those 17 days, overnight lows in water temperature recovered dramatically, in several cases to under 60°F. If clients were encouraged to be on the water by 6 AM, there’s plenty of daylight time to get a full day in prior that critical temperature threshold. In the context of an entire season, 17 days of paying attention to water temperatures seems pretty easy.

I say all of this only to point out that we do have readily available to us very granular data in at least a few locations to make informed decisions in real time (or close to it) with the simple bookmarking of gauge sites on our phones. In fact, many of us already do this. And also, to point out how critical the role of monitoring plays in management of resources. If we’re not paying close attention to the data, we can’t make progress and adjust our behaviors. It also highlights the importance of funding for gauges like the one in Ennis. It sure would be nice to have continuous data at this gauge. Though it’s been up and running since 2017, if you go look, there are wide gaps in the summer where the gauge was down for unknown reasons. We need this monitoring desperately, as climatic conditions continue to warm, and pressure continues to rise. We had 17 days above 70°F in 2020, but we have no idea how many we had in years prior leaving us blind to any trends at the moment.

As an outfitter on the Upper Madison, and despite my feelings about the efficacy or scrupulousness of the recently published rules for commercial use on the Upper Madison, I am very keen to my impact on the fishery as someone who takes people angling for a living. My job could very well have a negative impact on the fishery, if I’m insensitive or too casual about how I approach each day and each fish. I’m well aware that my job is to help people hook fish. And, as it turns out, hooking fish is not purely advantageous to the survivability for that fish. If too many times those hooking events leads to mortality, well you get the picture. My goal once a fish is hooked, is to return it to the water healthy. The more information I have at my disposal to accomplish this, the better. I’m determined to do better.

There are many things I as an outfitter and a fisherman can do to limit the effects of angling on each fish caught. Because I’m a small, mostly single boat outfitter unaffiliated with a shop or a lodge, most of these practices aren’t necessarily focused on how many boats I have on the water every day, because most days it’s just me. Rather, they include remembering to crimp barbs, limiting fighting time and handling time by gently encouraging clients to, you know, hurry up and get that thing in already, and minimally exposing fish to air after being landed, etc. This can be more challenging than some might think, especially when you have a first timer catch their first trout and they NEED a photo of that 12” rainbow trout. For larger outfitters, reflections such as how many boats to put on the water a day may be a consideration. One of the more difficult considerations is when to not fish at all based on water temperatures. Afterall, people pay me to help them catch and release trout. And, if the mere action of catching a trout prevents me from safely releasing that trout to live another day, well then the whole thing seems a bit senseless right? Bad business. Keeping fish alive is sort of advantageous to my bottom line, for lack of a better word.

Monitoring water temperatures and altering my outfitting behaviors accordingly is an easy way for me to reduce my impact on the fishery, as a catch and release small outfitter. By being more cognizant of when, where, and what the water temps are before and during fishing, especially in the middle of the summer, and adapting my trips accordingly, I can have a lesser impact on hooking mortality and in doing so, contribute to the long-term sustainability of the fishery. I mean, most days the topic of “what is the water temperature?” comes up anyway. Instead of stumbling an answer that it’s probably somewhere in the 60s, it’s more helpful if to explain exactly what it is (I now leave a thermometer hanging under the boat), and why it’s important.

And by the way, explaining this to clients and educating them is another aspect of the role we play as outfitters. What we shouldn’t do is meet them at 10 AM on an August afternoon and suddenly around 2 PM spring it on them that “hey look at that, the water temp is 70°F right now, time to bag this thing and head to the takeout pronto!” Maybe the day before the trip, we explain to them that it’s mid-August, gonna be hot, maybe we head out early in the morning to avoid the hot portion of the day and that, look, in order to avoid actually killing fish, if the water temp does hit 68-70 while we’re out there, we’re going to call it a day.

Lastly, a look forward. We as outfitters and guides are on the water virtually every day from say April to November. We need to be thinking of ways to collaborate with scientists and biologists on how to conserve our resource for future generations. And let’s be honest, the climate publicly right now for fishing outfitters on the Upper Madison is one in which we’re not viewed very kindly, deserving or not, and we could use the PR. One of the ways in which we could be instrumental, is to possibly literally operate instruments. As a former research scientist, myself, I think of all of us guides on the water as potential data points. Are there ways in which we could contribute to water quality and temperature monitoring? Mark and recapture via pit tagging trout? What if our nets had pit tag scanners on them, as a former research supervisor of mine has suggested? Sampling macroinvertebrates? Many of these tasks are quick and painless. The world needs data to manage resources, and we represent the only people who interact with that resource every single day. Collaboration is key. It’s time to think outside the box. Similarly, state agencies like FWP should be more willing to share data gathering responsibilities and be more flexible. There are many NGOs and user groups like us in the outfitting industry who stand ready to do our part in the hands-on work and in the wallet.

Aldo Leopold’s sage advice still seems relevant and analogous to rivers: “Our job is to sharpen our tools and make them cut the right way. The sole measure of our success is the effect which they have on the forest.” While I can’t directly control how cool our river is, there are many things I can control which will reduce my footprint on our resource. None of us can do everything, but all of us can do something.


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