The Nuances of Best Practices in Recreational Fishing

The Nuances of Best Practices in Recreational Fishing

by Dr. Shannon Bower

Lately, I’ve been thinking about a conversation I had a while ago. Partly out of guilt, because I have been a Science Ambassador for Keepemwet for quite some time and have been a fairly silent contributor of late, and partly because the issue of responsible fishing is always on my mind.

When you work in this field for a while, you learn that you can’t be militant about responsible fishing practices. There is simply too much variation in recreational fisheries to know what genuinely good practice is in every single situation. We have some great guidance papers, like Elmer et al. 2017, Brownscombe et al. 2017, and Sims and Danylchuk 2017 (2017 was a good year for best practices research, apparently!) and each of these offers a different take as well as some similar advice. This is a good sign that denotes a lot of agreement among researchers on this issue.

An image from the Brownscombe et al. 2017 paper that shows the different choices that anglers can make and the items they can have handy throughout the process of catching and releasing (or deciding to keep) a fish.

One place where we have some challenges in the field is in the arena associated with individual species. There was a paper by Cooke and Suski in 2005 that asked the question of whether we needed species-specific research to better understand fishes’ responses to catch-and-release. The answer was an emphatic yes, and the authors explored a range of reasons why, including arguing that we see so much variation that it’s difficult to accurately predict how each species will respond in a particular set of circumstances. In terms of variation though, Cooke and Suski pointed out that individual fish respond differently to the same catch-and-release practices, in much the same way that you or I would perform differently if asked to blow bubbles in the water for a full minute, i.e., I would fail miserably and you would probably do fine. As scientists, we’re interested in how the average fish responds to catch-and-release practices like air exposure, but we’re also interested in the range of responses for the whole population that we sample. There are as many potential sources of variation as there are types of responses to catch-and-release, and because of this, Cooke and Suski recommended that we get to work at understanding this variety of responses at the species level.

I think the same can be said for understanding best practices at the scale of individual fisheries, which is where this conversation that I had a few years ago keeps popping into my head. I’d made a post on my Facebook page about using nets when fishing. I had noticed a lot of people using cheap lip gripping devices on fish species with soft mouths that had no teeth. I was seeing photos of anglers in my study area using these devices to hoist the fish vertically out of water, and I wondered just how much pressure these cheaply made devices were putting on the fish’s jaws. I’d turned to the research to see if anyone had asked the question about the effects of lip gripping devices on fish and found a few articles that did nothing to alleviate my concerns (for example, Danylchuk et al. 2008, which was discussed here in an earlier blog. I had suggested that these anglers use nets instead, and to keep those nets in the water while removing hooks and preparing to release the fish. My logic was that the fish would be spared potential damage to the jaw and the air exposure being evidenced by the use of lip grippers. The risk was big though: if you’re using nets, you need to use rubberized nets to avoid damage to the fish’s body. Thrashing in a net that is not rubberized can lead to all kind of badness: major loss of slime that protects fish from infection, and physical damage such as slices and bruising being the two most major that come to mind. So, while I was clear to suggest using rubberized nets, I was also aware that these were not common in the area where I work and that I could be suggesting anglers simply trade one form of potential damage for a form of known damage to fish.

Raja PK photo.

Shannon Bower photo.

This advice didn’t sit particularly well with me, despite being the one who’d given it. I sat staring at the screen, thinking about phrasing, and wondering if there was a better avenue of action to suggest, when the telltale ping came through on my phone. It was a friend from Australia, also a recreational fisheries scientist, who disagreed entirely with what I’d written. What was of interest to me though wasn’t the disagreement, it was the reasoning behind it. You see, in his area of Australia, fishing mainly in marine waters, many anglers have learned that using lip grippers can be a very good way of avoiding the use of damaging nets, provided the lip grippers are suitable for the species and used properly. Those two provisos are a big deal: these anglers were using good quality devices that were appropriate for local toothy species and they were trained in how to use them properly. By doing so, the use of lip grippers was actually a best practice in the area. Yet in the area where I worked, using lip grippers was decidedly NOT representing a best practice. Best practices are not always universal. Like the Cooke and Suski paper arguing for species-specific research, I spend a fair amount of time arguing for fishery-specific research. We have a good sense of what many best practices are, but we don’t know how these best practices play out in different fisheries, in different communities, in different cultures and countries around the world.

Dave McCoy photo

All of this means that we have our work cut out for us as scientists. Incidentally, this is also the reason I am such a big fan of Keepemwet and their work. Of all the best practices, arguably the only one that is one hundred percent universal is: keep the fish in the water. When it comes to building local and fishery-specific understanding of responsible fishing practices, that is a great place to start.

THE POINT OF HOOKS

The point of hooks

By Sascha Clark Danylchuk

Hooking damage is the the number one cause of mortality for fish that are caught-and-released. That’s not a surprising statement since hooks are the only commonality for all fish caught by recreational anglers. But what that statement doesn’t address is how and why fish die from hooking damage. If every fish that is landed has a hook wound, what is it that makes some fish die and others live? How much damage do hooks actually cause? Does it matter what type of hook you use? What other factors come in the play to determine if a fish lives or dies after being hooked?

This paper looks at hooks and specifically hooking mortality in many different studies. It’s called a meta-analysis, which is a statistical analysis that combines the results of multiple scientific studies. It’s also a great introduction to Dr. Robert Arlinghaus, our newest science ambassador. Robert’s work is often based a social-ecological systems approach, which means that he looks at fisheries issues through the lens of both fish ecology and social science. You can learn more about Robert here.

What did they do?

Looked at hooking mortality studies for fishes that are important in European freshwater recreational fisheries. All species in a genus were included, even if the species were not found in Europe. Studies conducted anywhere in the world were included in the study.

• 107 studies on 8 European species and an additional 10 species from the same genus.

• Extracted what caused mortality from each study:

Water temperature

Fish length

Hook type (singe vs. treble)

Existence of a barb (barbed vs. barbless)

Type of bait (natural vs. artificial)

What did they find?

Across all studies and species:

• Mean hooking mortality was 15.9%, with a range of 0 to 88.5%.

• Half of the studies reported hooking mortality of less than 10%. Only a few studies reported mortality levels over 50%.

• Factors that are important for hooking mortality:

1. Water temperature (higher water temperatures lead to higher mortality rates).

2. Bait type (average mortality for artificial baits was 11.4%, average mortality for natural bait was 25%)

3. Existence of a barb (average mortality for barbless hook was 8.2%, average mortality for barbed hooks was 14.6%).

For Salmonids:

• Results for trout and salmon species was similar to the overall results.

• Factors that were important for hooking mortality:

1. Water temperature (higher water temperatures lead to higher mortality rates).

2. Bait type (average mortality for artificial baits was 11.6%, average mortality for natural bait was 27%)

3. Existence of a barb (average mortality for barbless hook was 8.6%, average mortality for barbed hooks was 15.1%).

Takeaways:

• The good news is that most of the reported hooking mortality rates were very low (less than 10%).

• High mortality was most often due to deep hooking or when fish were caught at high water temps.

• There are several reasons why barbed hooks could lead to higher mortality rates than barbless hooks: barbed hooks have been known to cause more injury and bleeding, they also take longer to remove which often increases handling time and air exposure (both things known to lead to worse outcomes for fish), and either or both of these could increase stress levels in fish which also leads to poorer outcomes for fish after release.

• Despite the fact that in this study hook type (single vs. treble hooks) did not turn out to be significant, the authors think that hook type is a species specific issue and likely dependent on hook size as well as the mouth morphology of the fish, and the type of fishing. All these factors could not be teased out in the present study, but are likely important on a species by species basis.

Bulkley Steelhead Catch-and-Release Project

Will Twardek photo

Recreational fisheries for steelhead are primarily catch-and-release, including the famed run of the Bulkley River, BC. The success of catch-and-release as a conservation tool is based on the premise that released fish survive and do not suffer any negative consequences. Science has shown, however, that angler behaviour can have dramatic influences on the outcome of catch-and-release angling, and that research is needed that specifically focuses on wild steelhead to identify opportunities for refining handling practices to ensure the best outcome for fish.

Scientists on this project worked alongside volunteer anglers on the Bulkley River to study wild steelhead from Sept 2016 to April 2018.  During this time, 126 wild steelhead were caught and used in one of two studies on the impacts of catch-and-release.  Click here for a full summary of the project.  

Read the published studies here, here, here, and here

Fish reflex tests - a valuable tool for anglers

by Dr. Jake Brownscombe, PhD
Research Associate, Carleton University
Keepemwet Science Ambassador

“Have a seat, Jake” the doctor said as she pulled out a small rubber mallet and proceeded to thump me on the knee with it. My leg kicked outward involuntarily. “Your nervous system is in good condition” she assured me.

If you grew up on this planet, you know the doctor was checking my knee-jerk reflex. Perhaps lesser known, the speed and intensity of this reaction can indicate internal nerve damage or the presence of disease. It’s a simple external test that indicates what is going on inside of the human body.

Fish have reflexes too. And they can tell us a lot about their internal condition, such as their level of stress, ability swim or to perceive predators. This is particularly useful for anglers because fish cannot tell us how they are feeling. If you ask a fish “If I let you go, can you swim well enough to survive?” its response will be inconclusive. Trust me, I’ve tried… more times than I’d care to admit.

The idea behind catch-and-release fishing is that the fish will survive, grow bigger to be caught again, and continue to contribute to the population. Yet, we know this isn’t always the case. Fish sometimes suffer mortality after release due to stress or injuries associated with angling (but the odds of this can be minimized substantially by using best practices - see this paper for an overview). Whether or not a fish survives depends on its condition, which can be hard to assess as an angler without any fancy medical or veterinary tools.

That is, until recent research developed a set of reflex tests that can be applied to fish, by anglers, to assess their condition. These are the four most effective reflex tests, how to do them, and what they tell you:

1. Escape response

How to do it:  With the fish in the water in a net or livewell (scientific holding pen shown here), approach the fish from behind and grab at its tail. Observe if the fish attempts to escape.

What it means: If a fish doesn’t try to swim away it fails this test, has at least some level of impairment and could be at risk of mortality - other tests will provide further insights.

2. Righting response

How to do it: Flip the fish upside down (belly up) in the water and let go. Observe if the fish rights itself within 5 seconds.

What it means:  If a fish cannot right itself within five seconds it fails this test, and is in poor condition and at risk for mortality.

Pro tip: Count the amount of time until the fish rights itself and note whether it struggled to do so. If a fish rights itself quickly and with ease, it is in good condition to swim away immediately.

3. Regular ventilation

How to do it: Holding the fish in the water, observe for regular, consistent ventilation (opening and closing) of the operculum (gill plates).

What it means: If a fish isn’t ventilating at regular intervals, it fails this test, and is highly impaired and at high risk for mortality.

4. Eye tracking

How to do it: Holding the fish in water, roll the fish side-to-side, observing whether its eye(s) remain level (passes test), or roll with the body (fails test).

What it means: If a fish fails this test, it is highly impaired and at very high risk of mortality

While these aren’t true reflexes by strict definition, they are responses that are always present in fish unless impaired due to stress. The above tests are presented in order of operation, starting with escape response. If a fish fails this test, proceed with the righting response test, and so on. If a fish has no reflex impairment, the best course of action is to release the fish immediately to reduce handling time. However, if there is reflex impairment, particularly loss of righting response, anglers can hold fish in a net or livewell until its condition improves. Further, on any given fishing day, if captured fish are repeatedly in poor condition, anglers can consider altering their fishing practices (e.g., use different lures or fish in different locations) to minimize their impact on fish.

The Science:

The concept of using reflex tests as an indicator of fish condition was first developed and applied in the context of commercial and aboriginal seine net fisheries for Pacific salmon (see these two articles for reference) 1, 2. Based on the success of multiple studies in predicting salmon survival using reflex tests, scientists began apply these tests to recreational fisheries. This study found bonefish with impaired righting response are six times more likely to suffer predation post release (see Finsights #5). Another study later showed that reflex impairment indicates that bonefish have reduced swimming and decision-making capabilities post release, which is why they are more vulnerable to predators. Reflex tests are now used widely as measures of fish condition for diverse species such as sharks, great barracuda, largemouth bass, and fat snook. As science continues to develop the relationship between reflex tests, fish condition, and survival, these tools will become increasingly useful for anglers to assess the condition of their fish and make informed decisions about how to treat the fish prior to release.

When scientists get together to talk fish

When scientists get together to talk fish

A couple weeks ago I attended the 8th World Recreational Fishing Conference in Victoria, BC, Canada. This gathering of 380 people from 22 countries included fisheries scientists, managers, students, and other fishy folk. We spent three and a half days giving and listening to presentations on topics such as citizen science, monitoring and assessment of recreational fisheries, understanding angler behavior, use and challenges of catch-and-release, and engagement of fishers in the management process.

While there was a lot of talk of scientific methodology, statistics, and other topics that could put most anglers to sleep (and has even been known to put fellow scientists to sleep), there were also a number of issues discussed that are relevant and valuable for anglers, especially for those of us that strive to follow KeepEmWet Principles and stay informed about fisheries issues.

Rick Hansen (Man In Motion) gives an inspirational opening address at the 8th World Recreational Fishing Conference about the impacts of fishing on his life. Andy Danylchuk photo.

Catch-and-Release
There were 33 presentations given in a symposium squarely focused on the use and challenges of catch-and-release in recreational fisheries.  A few of the highlights are:
    •    Deep hooking is the single most important factor influencing the survival of fish. If a fish is deeply hooked, it’s better to cut the line than try to remove the hook.
    •    The type of net you use matters – size of the mesh as well as the material can influence slime and scale loss, and fin fraying, but there still isn’t a comprehensive review and comparison of net types across a wide range of species.  
    •    Landing steelhead using either a net or tail grab is fine
    •    Everything we do to fish is magnified at higher water temperatures.  For example, while 10 seconds of air exposure may not significantly impact fish when water temps are low, 10 seconds of air exposure at higher water temperatures may be enough to temporarily impair swimming ability.  

Angler Engagement and Involvement
Starting with the keynote speakers there was a lot of emphasis on finding ways to interact with and involve anglers in the science and management of recreational fisheries.  Ideas ranged from creating interactive apps that provide data to scientists to having anglers guide research needs and creating partnerships where anglers help manage fisheries.  

It was encouraging to hear so many different people echoing this sentiment. Stay tuned for the roll out of several new KeepEmWet Science Ambassadors in the coming weeks; scientists who also fish and understand the passion and importance of anglers in making fishing sustainable. With this in mind, our goal is for KeepEmWet Fishing to be a platform for anglers and scientists to connect more directly.  

Finally, KeepEmWet Fishing was mentioned in at least eight different presentations (only one of which was by yours truly).  It seems that even scientists are starting to pay attention to social media and recognize the value in the KeepEmWet movement ;)

Happy Fishing!
Sascha Clark Danylchuk

Understanding the Complexity of Catch-and-Release in Recreational Fishing

Understanding the Complexity of Catch-and-Release in
Recreational Fishing: An Integrative Synthesis of Global
Knowledge from Historical, Ethical, Social, and
Biological Perspectives

Most research on catch-and-release (C&R) in recreational fishing has been conducted
from a disciplinary angle focusing on the biological sciences and the study of hooking
mortality after release. This hampers understanding of the complex and multifaceted
nature of C&R. In the present synopsis, we develop an integrative perspective on C&R
by drawing on historical, philosophical, socio-psychological, biological, and managerial
insights and perspectives. Such a perspective is helpful for a variety of reasons,
such as 1) improving the science supporting successful fisheries management and conservation,
2) facilitating dialogue between managers, anglers, and other stakeholders,
3) minimizing conflict potentials, and 4) paving the path toward sustainable recreational
fisheries management. The present work highlights the array of cultural, institutional,
psychological, and biological factors and dimensions involved in C&R. Progress toward
successful treatment of C&R might be enhanced by acknowledging the complexity
inherent in C&R recreational fishing.

Read full report here.

Lip Grippers

Lip gripping devices and your catch. Tiger fish. Dave McCoy photo.

Sport Fishing Magazine recently published an article on A Guide to Lip Grippers. The very last paragraph of the article touches on how lip gripping devices can impact fish and the author states “Many of the lip-grip manufacturers interviewed independently stated that they believe their weight scales do not cause physical damage to fish or inhibit future feeding ability — when the fish is hung vertically”.  I decided to dig through the scientific literature to see if anyone had looked at this at this and found only three studies that focused on lip gripping devices, each on different species.

 
Bonefish The first study looked at if lip-gripping devices caused injury to bonefish.  They compared bonefish held vertically in the air with a lip gripper to those held horizontally in the water with a lip gripper, all compared against a ‘control group’ where bonefish were handled only with bare hands   Bonefish held with a lip-griping device either vertically or horizontally were prone to injury – 90% of fish had at least minor injuries (which included holes through the tissue of the lower jaw where the lip gripping device was placed) and 35% of fish had major injuries (including broken mandible and separated tongue).  Conversely, only one of the fish held by hand had a minor injury and none had major injuries.  All fish survived for 48 hours after being handled, but the authors did not monitor for long-term survival or feeding ability.  

Injuries sustained to bonefish using a mechanical lip-gripping device. Link to report.

Barramundi In 2009, a different group of scientists looked at how lip grippers compared to nets for holding barramundi (an Australian sportfish).  They compared barramundi held in a net with those held vertically by a lip gripper, as well as those held horizontally with a lip gripper and one hand supporting the midsection of the fish.  They found that all fish held vertically and 81% of fish held horizontally had holes in their lower jaws.  However, no fish had severe injuries as was seen with bonefish.  Furthermore, all fish resumed feeding within 3-5 days and all holes healed within three weeks.  The scientists also took x-rays of some of the barramundi to see if holding them with lip grippers had any effect on their vertebral alignment.  They found that holding barramundi vertically, and to a lesser extent holding them horizontally with the lip gripper causes vertebral separation.  None of the vertebrae separations recovered after three weeks. Being water dwellers where the water supports much of their body weight, holding fish in the air has the possibility of causing damage or separation to vertebrae.

Florida Largemouth Bass The most recent study on lip grippers was conducted on Florida largemouth bass and examined the differences between holding largemouth bass vertically with a lip gripper, by hand on the lower jaw using a tilted grip, and using a two-handed hold.  They found no difference in feeding behavior, survivorship, or rates of injury between any of the three methods of holding bass.  They did, however, find that largemouth bass that were held with the lip-gripping device took longer to recovery than other fish.

Why are these studies important to anglers?
    •    These three studies constitute a start to the much-needed research on lip-gripping devices, and given the diversity of these devises and the species they are used on, clearly there is more work to be done.
    •    What these studies do show is that there is a wide variation in how lip-gripping devices affect the incidence of injury on different fish species.
    •    What I could not find are any studies that examine repeated use of lip grippers, long-term affects on fish, or compare injuries from lip grippers to those caused by nets.  
    •    If tackle manufactures want to make claims that their lip grippers and other fish handling products do not harm fish, they should consider independent testing.

Happy Fishing!
Sascha Clark Danylchuk

Fish Slime

How do you handle fish? Paul Moinester/Keepemwet Fishing photo.

You’ve hooked up on a fish.  You fight it, reel it in, and get ready to land it.  Do you reach for a net? A lip gripping device? Or just stick your hands in the water?  And what do you do once you have ahold of the fish?  Does it stay in the water? Does it go in a boat or a livewell?  

How we choose to handle the fish we catch and release can have a huge impact on the health of those fish.  Some of the negative effects of handling on fish we can actually see (such as the loss of scales or equilibrium) but many we cannot, either because they are invisible to the naked eye, are internal, or occur after we release the fish.  

This study uses a clever way to examine some of the invisible injuries to fish and how different handling techniques impact the skin of fish. All fish are covered with an epithelial layer, which is on top of the scales and provides a barrier to pathogens, UV light, and desiccation (drying out). There is also mucus on fish, but the amount varies among species. Unlike with humans, the outer layer of cells on fish are living and a disruption to the epithelial layer creates a susceptibility to infection.

Fluorescein is a non-toxic dye that can be used to examine epithelial damage on fish (it is some of the same stuff used by detectives to look for blood at crime scenes). After being dipped in a solution containing fluorescein, areas on a fish with damaged epithelium with glow green under a UV light.   

What did they do?
    •    Used fluorescein dye to examine how different handling methods damage the epithelial layer on largemouth bass and northern pike.
    •    Handling techniques included different types of nets, a lip gripping device, and placing a fish on a variety of boat surfaces.
    •    Largemouth bass from a semi-professional live-release tournament were also measured for epithelial damage.
    •    After being subjected to the fluorescein dye, fish were photographed under a UV light and damaged area (seen as green on the photos) was measured using computer software.

A northern pike photographed under UV light after being exposed to fluorescein dye. The green areas indicated epithelial damage from handling. Image from linked report.

What did they find?
    •    Northern pike had more epithelial damage than largemouth bass across all handling methods
    •    Largemouth bass from the tournament had the most epithelial damage. This isn’t surprising as they were often subjected to multiple handling methods, where the experimental fish were only subjected to one handling method.  
    •    Rubber, non-knotted landing nets caused less damage than nylon, knotted nets for pike. For bass, there wasn’t a difference between net types.  
    •    All fish placed on a boat surface had epithelial damage and those placed on indoor/outdoor carpet had more damage than those placed on a bare metal surface.

Why is this study important to anglers?
This study shows that different species can have different reactions to the same type of handling. This is one of the reasons the science of catch-and-release is so interesting and can be confusing, and why ‘one size fits all’ rules may not apply. Nevertheless, here are two generalities that we can uphold because they are supported by this study (and others) and follow the precautionary principle – the idea behind “better safe than sorry”.  

    •    This study confirms what many anglers have thought for a long time; that softer, rubber, non-knotted nets are better for fish.  
    •    Likewise, contact with boat surfaces (carpet or smooth metal) causes damage to fish and rough surfaces cause the most damage. I would argue that placing fish on any hard surface (rocks, logs, boats) either wet or dry has the potential to cause epithelial and internal damage to fish. Whenever possible, fish should be held over water deep enough for them to swim in. But remember, we also need to #KeepEmWet.

See the complete study here.

Happy Fishing!
Sascha Clark Danylchuk

The Science of Catching more Fish

By Sascha Clark Danylchuk

Science to help you catch more fish. Bryan Huskey photo.

I want to introduce a new type of scientific paper, called a review paper.  So far, the literature I have used has been based on single studies.  Every once in a while, however, scientists will gather together much of the literature about a given topic, summarize it, and be able to draw new or stronger conclusions due to the support of multiple studies.  While review papers often lack the detail of papers based on individual studies, they are very helpful in advancing a discipline or subject area.  

Just a couple months ago there was a review paper published on what makes fish vulnerable to capture by hooks.  Because fishing is not a random process, some species or individuals within a species are more likely to be caught by anglers than others.  Likewise, at any given moment some fish may be in a vulnerable state while others are less vulnerable.  There are many, many factors that influence fish vulnerability and as anglers we know that what worked yesterday to catch a fish may not work today. The authors of the review paper have used a three-part framework to discuss the various aspects of vulnerability - represented by the yellow triangle in Figure 1.  There is also a video accompanying this paper.

"Vulnerability of fish conceptualized as a dynamic state-switching process in which fish transition into states of vulnerability as a function of the internal state, the encounter with the predator (i.e., fisher), and the selectivity of the gear. We also show how vulnerability is modified across axes of life history and environments and how it can be modulated by management actions such as fishing restrictions. Fish vulnerability is only observable insofar as the fish is captured, making it difficult to empirically quantify. Nevertheless, these concepts are the foundational mechanisms driving vulnerability."

Internal state
What is going on inside an individual fish and the factors that influence a fish to eat and strike comprise its internal state.  While the need to eat in fish is controlled by metabolism (just like in humans) there are many environmental factors that play into this, especially as fish are cold blooded.  The abiotic factors are those that are non-living such as physical (temperature, light, lunar phase) and chemical (dissolved oxygen, pH, salinity) properties of the environment.  The biotic environmental factors are the other living organisms including other fish of the same species, as well as predators and prey.  

Predatory encounter
When a fish is hungry or motivated to feed, you can think of it as a predator looking for prey.  The chance that the prey will be the hook on the end of your fishing line is the “predatory” encounter.  The probability of hooking a fish depends where a hungry fish is as well as where your fishing gear is – you will never catch a fish if there aren’t fish close to you to be caught.  Predatory encounter relates to the spatial components of vulnerability including fish and human movement patterns.  

Gear selectivity
The type of fishing gear we use, either by choice or regulation, ultimately determines whether you will catch a fish that is hungry and in the right place at the right time.  Fishing gear is selective, meaning it works better on certain (sized, shaped, or species of) fish.  Incorrectly selected gear (e.g. the wrong species of fly) can turn a vulnerable fish back to the invulnerable state.  Similarly, the ability of fish to learn in catch and release situations also influences gear selectivity.  

Why is this important for anglers?
As anglers, we talk and think about fish vulnerability constantly.  We talk about the bite being on or off, which flies or lures work, what moon phase is best for fishing, where the secret spots are, and on and on and on. There are books and magazines and blogs devoted to the topic.  Likewise, there are at least as many fishing theories out there as there are anglers.  While some of the factors that influence fish vulnerability are in an angler’s control, many are not.  Thinking systematically and using this mechanistic approach to vulnerability just might help you have more success the next time you are on the water.  

Read the entire review paper here.

Happy Fishing!
Sascha Clark Danylchuk

Fish vulnerability by Robert Lennox.

SCIENCE NOTES FROM JOHN MCMILLAN

Wild steelhead image from Keepemwet Science Ambassador John McMillan.

Fitness. I bet you have heard the term if you love #steelhead and #salmon, particularly if you pay attention to research on hatchery and wild fish. Studies that compare the performance of hatchery and wild steelhead often measure fitness. So what does it mean? Well, in this case it doesn’t exactly refer the physical fitness most of us think about on a day to day basis. It’s not about how far or fast we can run, nor about how strong or tough we are. In fact, it has very little to do with that concept because it really only considers physical aspects and does not incorporate a mental or learning aspect, nor does it account for luck or chance. Rather, fitness in evolutionary biology is the measure of an individual’s ability to survive and reproduce offspring. In studies of steelhead, and other salmonids, the measure of fitness is often described as an individual’s contribution to the next generation. It is a sum measure of survival at different life stages, such as from egg-to-fry, fry-to-parr, parr-to-smolt, and smolt-to-adult. Basically, individuals with higher fitness do a better job of producing offspring relative to other members of the population. Individuals with lower fitness do not do as well. While many studies have compared the fitness of wild and hatchery salmonids, the term is also important to understanding the value of diversity. If you recall, I have previously posted about the remarkable number of life histories that steelhead display. The diversity helps dampen annual fluctuations in populations relative to species with fewer life histories. Why? Because some life histories life histories perform better – aka., have higher fitness – in some years and places than others. Maybe the wild steelhead in this photo will be one of the few that passes along its genes to the next generation, and if so, it might have nothing to do with how fast or strong it is. It may come down to something like nest site selection, or maybe even chance. #fishing#flyfishing #wildsteelhead #biology #science#rivers  #spey #conservation#pnwwonderland #uwphoto #snorkel

“I saw the fish swim away so it must be fine” - Part 2

“I saw the fish swim away so it must be fine” - Part 2

Golden dorado pondering the outcome of it's next meal. Dave McCoy photo.

My last article aside, we assume that most of the fish that we catch and release actually live. But, does catching and releasing a fish have any impact on it?  Maybe.  Does an angler have any control over what these impacts are?  Sometimes.  

The slew of possible impacts of angling on fish are called sublethal effects. A lot of catch and release angling science has to do with minimizing or explaining the sublethal effects, so it’s important to understand what those can be and how different aspects of angling can have different sublethal effects.  

Fig. 1. from the linked paper. Conceptual diagram outlining the immediate and long-term effects of escape or release from commercial fishing gear and how it relates to each level of biological
organization. Question marks (?) denote areas for which no primary literature exists, and present future avenues of research.

For this post, I’m focusing on one figure from an article.  Don’t be put off by the fact that this article deals with commercial bycatch and not recreational angling – the issues for released fish are the same, and this paper is widely referenced in the recreational fisheries science literature (not to mention that several of the authors work on recreational fisheries too).  

So, here it is, a rundown of the potential sublethal effects of angling:

Immediate Sublethal Effects
This deals with the acute effects of angling on fish and are most obvious to fishers.  
    •    Physical Injury.  Hooking wounds are what usually come to mind, but don’t leave out blood loss, foul hooking injuries, and injury that occurs during handling and hook removal.
    •    Physiological responses.  Physiology deals with the functions of an organism or it’s systems/parts.  A physiological response occurs when an event (such as angling) causes an animal to function beyond its “normal” activity levels.   This is most often measured via a blood sample in fish (see Finsights #4 for more details).
    •    Reflex impairment.  This is most easily thought of in human terms – when you’ve had one too many and can’t walk a straight line, you have reflex impairment.  For fish, this could include the loss of equilibrium (see Finsights #5), or lack of coordinated movement between the mouth and gills.  

Testing the reflex impairment of golden dorado on the Rio Juramento, Argentina. Tyler Gagne photo.

Delayed Sublethal Effects
If the immediate sublethal effects are severe or last long enough a fish could end up with these.
    •    Behavioral impairment.  This could include anything from spawning to swimming behavior.  
    •    Altered foraging efficiency = altered ability to find, compete for, and capture food.
    •    Growth and wound healing.  Animals that must spend energy on wound healing can have decreased growth.
    •    Altered energy allocation has to do with how a fish apportions energy (e.g. energy derived from food) to the life traits of growth, reproduction, and survival.
    •    Immune function and disease development & offspring quality, performance, and survival & reproductive success.  All of these have to do with the point above; when more energy is needed for one of the three life traits, one or both of the others get less energy.  

All of the sublethal effects above only refer to what happens to an individual fish.  It’s possible that these individual level effects can also impact the entire population.  For example, if enough fish experience decreased reproductive success, this could lead to less fish in subsequent generations.  

It’s this step - moving beyond what happens to one fish to the population - that is particularly challenging for the field of catch and release science.  In part, this is because it’s a really hard thing to do - to show, definitively, that sublethal effects at the individual level can have cascading effects on an entire population or community.  In future posts, I will dig into some of the studies that have begun to chart this course.  

As anglers, the more we can do to decrease the sublethal impact of angling on individual fish, the less likely there are to be higher-level effects.

Happy Fishing!
Sascha Clark Danylchuk

“I saw the fish swim away so it must be fine” - Part 1

“I saw the fish swim away so it must be fine” - Part 1

The "grey ghost" Alex Filous photo.

I can’t tell you how many times I’ve heard an angler say, “I saw the fish swim away so it must be fine.”  And I’ve certainly hoped for the same on countless occasions; that when I release a fish that’s vigorous and darts out of my hands it will be fine.  The scientist in me, however, knows that this statement can be false for a number of reasons.  

Sometimes the fish we catch and release get injured or die.  There is no getting around that fact and there is only so much that is in an angler’s control.  However, by better understanding the processes that can lead to negative outcomes for fish, we anglers can adjust what is in our control to ensure that more fish live to be caught another day.  

This post is the beginning of a series addressing what can happen once we release a fish.  This particular post addresses post-release predation, and (in full disclosure) a paper authored by me.  Despite the fact that using this paper makes the introvert in me want to hide under the bed, I chose it because it is a fairly straightforward study with results that have a clear application to the catch and release best practices for bonefish.  

What did we do?
    •    Bonefish were caught using fly fishing.
    •    Measured angling time (hooking to landing), handling time (landing to release), air exposure time (cumulative), the presence/absence of blood from hooking, and total length of the fish.
    •    Also noted whether or not the bonefish was able to maintain equilibrium at the time of release.  Having equilibrium = fish that swim away. Lost equilibrium = fish that rolled over or nose-dived and couldn’t readily swim away.
    •    Before release, we attached a small float to the bonefish so that we could follow it (this tracking method was previously tested on bonefish and there was no impact of the float on fish movement and predation)

Post-release predation on bonefish by a shark, Robert Lennox photo.

What did we find?
    •    Bonefish that lost equilibrium were over 6 times more likely to suffer predation, either by sharks or barracuda
    •    Longer air exposure and handling times were the biggest contributors to loss of equilibrium
    •    Predators killed most of the bonefish within 20 minutes of release, but not necessarily close to or within easy viewing of the release location.

Why is this study important to anglers?
    •    Air exposure isn’t good for bonefish
    •    Lots of handling isn’t good for bonefish
    •    Catch and release angling in locations with predators (even if you don’t see the predators) can greatly decrease the chance of survival for fish.

Read the full study here.

Happy Fishing!
Sascha Clark Danylchuk

Fish Can get Stressed Too

Fish can get stressed too

By Sascha Clark Danylchuk

Rainbow trout darts back into it's Alaskan stream after release. Bryan Huskey photo via Bristol Bay Lodge.

Before we dive into the study (Meka & McCormick 2005), I wanted to start with a brief discussion of stress in fish.  Scientists measure stress in fish to determine how our interactions with fish (e.g. angling) affects their health and welfare. Just like in humans, too much stress in fish can lead to decreased performance, poor health, and even an increase in the likelihood of death.  There are a variety of indicators that can be used to quantify stress, each with advantages and disadvantages. Two of the more common indicators are cortisol and lactate.

Cortisol: a hormone found in all vertebrates and often called “the stress hormone”.  You could think of cortisol as a messenger, and an increase in cortisol can trigger a response in numerous parts of the body.  When scientists measure cortisol level in blood, we assume that a higher level of cortisol is indicative of a higher level of stress.  

Lactate: a byproduct of extreme muscle activity.  For the athletes out there, it’s related to lactic acid buildup in muscles due to anaerobic activity.  In the context of angling, higher levels of blood lactate indicate that a fish has been exercising more in response to being on the fishing line, and is more stressed.  

So, back to the study, this one examines the stress caused by angling for wild rainbow trout in Alaska.  

What did they do?
    •    Used real angling techniques (spin and fly fishing)
    •    Compared rapid capture fish (less than 2 minutes from hooking to hook removal) to extended capture fish (over 2 minutes from hooking to hook removal)
    •    Took blood samples after the hook was removed to measure cortisol and lactate (and a couple of other parameters, which I’m going to ignore for now)
    •    No air exposure to any fish

What did they find?
    •    Extended capture fish had higher levels of cortisol and lactate
    •    Larger fish took longer to land
    •    All else being equal, higher water temperatures can (but don’t always) correspond with higher levels of lactate and cortisol

Fly fishing the Alaskan backcountry. Bryan Huskey photo via Bristol Bay Lodge.

Why is this study important to anglers?
    •    Choosing tackle that reduces the amount of time a fish is on the line and the time it takes to handle the fish and remove the hook is important to reducing stress.  
    •    Bigger fish that fight longer are likely more stressed

See the full study: Physiological response of wild rainbow trout to angling: impact of
angling duration, fish size, body condition, and temperature
Julie M. Mekaa,∗, Stephen D. McCormickb

Happy Fishing!
Sascha Clark Danylchuk

A classic air exposure paper

A classic air exposure paper

by Sascha Clark Danylchuk

Rainbow trout resting before release. Bryan Huskey photo.

Please note that we have updated this post because the study discussed has been misinterpreted and taken out of context.   The importance of the Ferguson and Tufts 1992 study is that it was the first to demonstrate the potential magnitude of impact that air exposure can have on fish.  HOWEVER, the numbers from that study are NOT meant to be representative of what happens in real fishing situations!!!!  I cannot emphasize this point enough!

Happy Fishing!
Sascha Clark Danylchuk

For the first Finsights translation I wanted to start with a classic manuscript about air exposure and fish, and arguably, the paper that started it all.  The paper (linked here and at the bottom of this page) is titled “Physiological effects of brief air exposure in exhaustively exercised rainbow trout (Oncorhynchus mykiss): Implications for ‘catch and release’ fisheries” and was published in the Canadian Journal of Fisheries and Aquatic Sciences in 1992 by Ralph Ferguson and Bruce Tufts.

What did they do?
In this study, the scientists compared three groups of rainbow trout:
    •    Fish that were exercised
    •    Fish that were exercised and air exposed (for 60 seconds)
    •    A control group of fish that were neither exercised nor air exposed
Because this experiment was performed in a lab, chasing trout around the tank was used as a proxy for exercise, which is how scientists think of angling or fighting a fish.  

They then measured a bunch of different blood parameters that are used as indicators of stress.  I don’t want to go into the details of blood chemistry here – it can be confusing and I don’t think necessary to understanding the main points of this study – but I do want to point out that this is a very common way to look at the effects of angling on fish.  

Lastly, the scientists looked at the survival of fish in each of the three groups and also added another group that was exercised and air exposed for 30 seconds, but where no blood samples were taken.  

What did they find?
    •    Air exposure made a big difference!  
    •    Rainbow trout that were air exposed were more stressed and exhausted than any of the other fish.
    •    More fish that were air exposed died compared to those that were just exercised.

Why didn’t the air-exposed trout survive? The scientists argue that the trout that were air-exposed died because fish gills don’t work in air.  Gills consist of tiny, delicate structures, called lamellae, where oxygen exchange occurs.  Water flow across the lamellae is essential for proper functioning and for a fish to breathe (oxygen in, carbon dioxide out…just like us).  When fish are lifted out of the water, the lamellae collapse and stick together and the fish can’t get any oxygen.  

Imagine running a marathon and then being forced to hold your breath – your body (and likewise that of an angled fish) would be deprived of oxygen at the precise moment that you needed it the most.

Rainbow trout lifted slightly as it's released. Bryan Huskey photo.

Why is this study important to anglers?
The authors end this paper by making a very important point: Because this study was performed in a lab, with hatchery rainbow trout, and with exercise as a proxy for angling their results are not intended to be predictive of what would happen in an actual angling event. BUT, their results do clearly indicate that air exposure is important and can have a big impact on the well-being and survival of angled fish.

This paper got the scientific community to begin to start thinking about the different parts of an angling event (air exposure, hook type, fight time, etc), and how each might influence the stress and survival of fish.  Since this paper, the scientific community has done much more on stress related to angling, and with many more species, especially wild fish being angled in natural settings.

Lastly, I just listened to an excellent interview titled “Why should we believe in science?”  If you are still curious about the scientific process I enthusiastically recommend this eloquent interview with Naomi Oreskes, as well as her TED talk on the same subject.  

Happy fishing!
Sascha Clark Danylchuk

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 Click here to view "Physiological effects of brief air exposure in exhaustively exercised rainbow trout (Oncorhynchus mykiss): Implications for ‘catch and release’ fisheries”

Science Notes from John McMillan

Chrome steelhead via John McMillan Instagram @rainforest_steel.

One of the great aspects of Instagram is meeting a number of people who share a similar interest in #fish, #rivers, and #fisheries. I was fortunate to be raised with a father, who very early on, promoted best handling practices for catch and release of #wildsteelhead and other #salmon and #trout we released. We also promoted the wood shampoo for those fish we kept and ate. But as our fish populations decline and opportunities for #fishing for #steelhead and salmon also decrease, we are faced with increasing pressure in fewer fisheries. To effectively share the resource, anglers have largely shifted to releasing wild steelhead. And over the past decade there has been a dramatic increase in implementing best handling practices to try and minimize our impacts. We love to catch the fish, and that comes with some cost to the animal. Nonetheless, the way we treat the fish is important because it can reduce stress and improve chances that the fish recovers from the experience more quickly and with less physiological impact. This is one reason I completely support the @keepemwetfishing movement, and why I felt honored when Bryan Huskey asked if I was interested in being an Ambassador. I feel privileged to be included with such a strong group of anglers, photographers, advocates and scientists. I understand some anglers eschew #keepemwet, and I am not here to take offense. I am not above anyone, we are all anglers. Yet, I would also ask that all anglers consider their handling practices. Recent research on Atlantic salmon found that even short amounts of air exposure (< 10 seconds) had some negative effects on reproduction. It is but one study, but studies on other species have also found effects of air exposure on physiology and survival. Regardless, we don't exactly understand the full effects, perhaps they are less, perhaps more. More importantly, if we want these fish to not only survive, but recover quickly and hopefully in the case of steelhead -- return to spawn again -- I don't see a tremendous inconvenience in keeping most of the fish in the water. After all, it is us who will benefit. #flyfishing #spey #handlefishwell #speynation #flyfish

Coho salmon eyeballing a hatchery steelhead via John McMillan Instagram @rainforest_steel

What is wrong with a #hatcherysteelhead that came from two #wildsteelhead parents? A recent study addressed this question. Scientists from Oregon State University mated two wild #steelhead and reared the offspring in the hatchery. After only one year, 723 genes were differentially expressed in the hatchery steelhead. The differences were related to wound healing, immunity function and metabolism. This indicates that steelhead adapt rapidly to the conditions in hatcheries, and a potential cause is the high density of fish.

For example, changes in wound healing and immunity function could prove beneficial when tens of thousands of juveniles are crammed into a small raceway competing for food and space. It may help alleviate fungal infections and other issues caused by the constant nipping and biting that arises in such situations. The same goes for metabolism. Steelhead and other salmon with faster metabolisms are more aggressive. More aggressive fish do better in hatcheries because they obtain more food and grow faster than their cohorts with slower metabolisms. Larger smolts survive much better than smaller ones.

So, why would selecting for a faster metabolism be bad? It's not, if you live in a hatchery. But if you live in nature, it can be a detriment. Food is typically limited in nature, so those ultra-aggressive individuals may do well during the rare years when food is really abundant and competition is high, but they are likely to suffer increased mortality in most years when food supplies are normative – they may starve or be killed by predators because they have to take too many risks to meet their caloric requirements. Hard to focus on hiding in a log-jam when the belly is screaming, Feed Me! The worst part: we now know the genetic changes that helped them survive in the hatchery are passed to their offspring that will live in nature, and hence, this is one reason hatchery steelhead – even those from wild parents – survive poorly compared to wild fish. #science #ecology #biology #fishing #flyfishing #uwphoto #snorkel #underwaterphotography #spey #keepemwet

Involving recreational fisheries stakeholders in development ofresearch and conservation priorities for mahseer (Tor spp.) of Indiathrough collaborative workshops

The mahseer (Tor spp.) of India are a group of potamodromous cyprinids currently facing numerous challenges in their native ranges including overfishing, pollution, and hydropower development. As a result of such challenges, four of the seven Indian species of Tor have been listed as ‘Endangered’ on the IUCN Red List, including two of the most popular recreationally fished species, Tor khudree and Tor putitora.Stakeholders in the mahseer recreational fishery may serve as an ally for this group of iconic fishes, fostering aquatic stewardship and providing livelihood alternatives for poachers. Yet, information regardings pecies-specific responses to recreational fishing practices is lacking and a 2009 decree equating fishing with hunting in the Indian Wildlife Protection Act (1972) has since 2011 effectively banned angling within protected areas and rendered the future of mahseer recreational fisheries elsewhere uncertain. Read More.

Evaluating the consequences of catch-and-release recreationalangling on golden dorado (Salminus brasiliensis) in Salta, Argentina

Golden dorado (Salminus brasiliensis) is increasing in popularity as a target of recreational anglers practicing catch-and-release (C&R) in northern Argentina and bordering countries, however science-based best practices have yet to be developed for this iconic freshwater game fish. We assessed the consequences of C&R on golden dorado captured by anglers on the Juramento River, in Salta, Argentina. Read More.

Inserting the angler into catch-and-release angling science and practice

In August of 2015 recreational fisheries researchers, managers,and stakeholders assembled at the American Fisheries Society Annual Meeting in Portland, Oregon to discuss the current state of catch-and-release angling science and practice in the 21st century. Beyond providing a venue for participants to share the latest science on the topic, there was a strong emphasis on understanding how the science relates to or could inform practice. Read More.

Best practices for catch-and-release recreational fisheries – angling tools and tactics

Catch-and-release angling is an increasingly popular conservation strategy employed by anglers voluntarily or to comply with management regulations, but associated injuries, stress and behavioural impairment can cause post-release mortality or fitness impairments. Because the fate of released fish is primarily determined by angler behaviour, employing ‘best angling practices’ is critical for sustain-able recreational fisheries. While basic tenants of best practices are well established, anglers employ adiversity of tactics for a range of fish species, thus it is important to balance science-based best practices with the realities of dynamic angler behaviour. Here we describe how certain tools and tactics can be integrated into recreational fishing practices to marry best angling practices with the realities of angling. While the effects of angling practices vary considerably across contexts and conditions, we also outline available methods for assessing fish condition by examining physical injuries and reflexes, which enable recreational anglers to make educated real-time decisions related to angling practices, as well as when, where, and whether to release captured fish based on their probability of survival. In cases where fish are in poor condition, there are recovery tactics available that can improve survival, although this is among the most understudied aspects of angling practices. Read More.

Perceptions of recreational fisheries conservation within the fishingindustry: Knowledge gaps and learning opportunities identified ateast coast trade shows in the United States

"The recreational angling community is comprised of diverse stakeholders, including the trade sector responsible for the manufacturing, distribution, and sales of tackle, boats, and clothing, angler-based travel, revenue-generating popular media, and angling services. Through marketing and promotion, fishing companies compete for customers by convincing anglers as to what success means when they go fishing. If the angling trade can influence the social norms in the recreational angling community, then this could hold true for norms related to the conservation of recreationally targeted fishes and their habitats." Read More