Is Facebook Killing Trout?

In a case of "do as I say, not as I do," here I am taking a photo of a memorable-sized brown trout. Notably, that bucket is full of water, though.

We’re all guilty. Maybe you’ve just caught a huge fish, are fishing a new spot and catching a cool new species, or perhaps your son or daughter just caught the first fish of their life.  Regardless the occasion, what’s one of the first things a lot of us do?  We reach into our wader pockets and grab our phones to document the occasion with a few well-staged photos and share them to Facebook, Twitter, etc.
It seems innocent enough. Afterall, you probably used the best barbless tackle, took all the proper handling precautions, and snapped the photo as fast as possible. And, you watched as the fish swam off. No harm done, right?

Actually, you might be surprised to learn that a recent study found that up to a 1/3 of all fish photographed by anglers died within the next day.

I personally found that number a little startling but, let’s take a deep breath before we jump to conclusions. We have to recognize that the mortality rate is obviously going to depend a lot on angling method, photography method, time of year, etc. So, let me set the stage a little. The researchers were targeting a lake-dwelling population of bull trout, where water temperatures were about 56°F. So, not overly warm, and surely not as thermally stressful as a lot of trout streams we fish in summer. Tackle included barbless hooks, and fish were landed as soon as possible. In other words, the angling conditions were basically ideal.

On one day all fish that were caught and were of “memorable” size were photographed twice, measured for length, and then photographed twice again (more on what I mean by “memorable” below). This behavior sounds a bit bizarre, but other studies have shown it’s typical angler behavior after catching a big fish- they call their buddy over to snap a photo, measure the fish’s length, and then usually take photos of the fish being held by their fishing partner. All in all, the time from the fish being caught to released was less than two minutes. Two minutes sounds like a long time but, again, studies have shown that it’s generally about the length of time most people hold a fish before its released, and I guarantee you the clock ticks a little faster with your adrenaline rushing. And, if you really want to argue, other studies have shown negative effects of air exposure after only 10 seconds. Good luck fumbling to get your $800 phone in the middle of the stream in less than 10 seconds.

So, that was day one.  On day two the researchers did the same procedure. Only this time any memorable-sized fish were immediately released. Importantly, in both instances fish were released into a holding pen. Then, 24 hours later, the number of dead fish in each pen was counted. 

The result? In the group of photographed fish 10 of 30 (33%) died. In the fish that were immediately released, 3 of 20 (15%) died. What this tells us is that, even for the most experienced anglers working in some of the best fishing conditions, there is mortality associated with catch-and-release fishing. This is important because we assume that catch-and-release protects a fishery, and it does to a large extent. But, there is a category of mortality, known as cryptic mortality, that is difficult to account for and includes things like death from injury, illegal harvest, and prolonged handling. While mortality from harvest and injury is near 100%, it’s not a common outcome for most fish. However, many fish experience prolonged air exposure and, though mortality from air exposure is not 100%, it adds up to eventually account for a significant proportion of deaths in a fishery. And, access to more portable cameras (i.e., smartphones) and increased social medial influence may increase the likelihood that fish are exposed to air for longer durations.

Of course, we have to consider these numbers with a bit of caution. Fish weren’t released back into the lake, but rather into confined pens. This could have increased stress, and thus artificially increased mortality rates. But, the researchers noted that most deaths occurred almost immediately upon release. And, the pens had pretty nice accommodations. If anything the physiological responses to prolonged air exposure (reduced swimming ability, increased thermal stress, etc.) may actually have less effect for fish that are released into a protective pen, in which case the study may underestimate mortality associated with photography. In fact, after the study was over, the researchers released the fish back into the lake and found that two fish that were technically alive sat next to the pen for over four hours, appearing to be weak and near death. So, arguably, you could say that 40% of photographed fish died during this study.
Another important point is that this study was conducted on a fairly remote lake, and so the fish had only been caught the one time. In reality, fish that survive one landing are likely to be repetitively caught in a catch-and-release fishery. Every time that fish is caught and handled there, the probability of it later dying is going to increase. And, potentially, the effect of previous handling could make a fish more susceptible to prolonged air exposure in a later catch.

Now, I want to return to the fact that this study also focused only on memorable-sized fish. In fisheries science, “memorable” is a technical definition that means exactly what you would think- a fish that is large enough to be remembered. But, for the purposes of this study, memorable also means a fish that is larger than you would normally catch, and so the chances of dropping the fish or awkwardly handling it are higher. Subsequent review of the photographs showed that most fish were covered in mud, indicating they were either dropped in the process of taking the photo or there was increased struggle trying to land the fish. The focus on large fish may seem a bit biased but, think about it, do you bother taking a photo of many of the smaller fish you catch?  Probably not. Plus, understanding delayed mortality of larger fish is potentially more important as the larger fish are likely those that will produce the most offspring, may have different movement behavior than smaller individuals, or may have unique genetic diversity.

So, how do we possibly prevent photograph-induced mortality. Some states, such as Washington, have made it illegal to totally remove some species from the water if you are going to release it back into the stream/lake. So, basically, the only way to take a photograph with a salmon, steelhead, or bull trout in Washington is if you are also taking it home to fry.  Is this a reasonable practice?  Maybe, but it’s difficult to enforce. Ultimately the best way to decrease mortality from prolonged air exposure is by influencing individual angler conduct. In other words, we need to self-enforce best angling practices that minimize fish air exposure. This is particularly critical in summer, and in streams/rivers with flow, as these conditions are going to maximize post-release mortality.

So, maybe think twice before you click the “Like” button on a picture of your friend standing on a boat or streamside with their prized catch. 

This post was inspired by recent research published by Brian Joubert and colleagues. I would encourage all to read the original manuscript found here. 

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