Painting by Diane Michelin

Painting by Diane Michelin

We are pleased to feature this guest blog post from Lenny Tamule.  Lenny is a recent graduate of UMASS Amherst where he majored in Natural Resources Conservation with a concentration in fish ecology.  Lenny also just finished up a season as a guide at Las Pampas Lodge in Argentine Patagonia.  Prior to heading to Patagonia, he had an opportunity to review a recent paper on landing nets, as well as offer a personal reflection on his past use of nets.  


The author Lenny Tamule admiring a stout #keepemwet fish.

The author Lenny Tamule admiring a stout #keepemwet fish.


It was a calm and cloudy October afternoon and that means brown trout. Within minutes, I was heading to the river. I arrived with my best bud Sully and we got right to it. We made our way down the bank in a spot that had no path. As we approached the river I saw a shadow that isn’t usually there; it was a rather large brown trout. After countless heart racing drifts, my leader stopped, and I was connected. There was a lengthy battle in a heavy rifle and fish was in the nylon net. A combination of being a broke student and new to fly fishing, a cheap, $15 net was all we could really afford at the time. The fish was too big for the small net, and its head almost stuck out. I took a quick photo (regrettably out of water) and put the fish back, but the fish wasn’t swimming and had lost the ability to keep itself upright. I nursed it and tried everything I could to get water passing through its gills but they remained shut. After some time the fish finally swam off. I was relieved. Thirty minutes later we went downstream to fish the next pool. It was then that I saw a sight that made my heart sink deep into my stomach; an upside-down mass on the bottom of the river bed. As someone who prides himself on using best practices for handling fish and getting them back to the river as soon as possible, this was devastating. 


I’ve never shared this story with anyone, perhaps due to embarrassment, but I hope this story will encourage all those who read it to be as smart and kind as possible to the fish they catch (because that day I certainly wasn’t). I don’t know what caused that fish to die — was it the net not supporting it properly, or causing spinal injury, or just myself poorly handling the fish. Whatever the reason, I hope this particular study on nets as well as other catch-and-release studies can help all of us use the best release methods so that no one has to see and experience what I did that day. 


Given the vast number of people who partake in catch-and-release angling, we still do not have as much science on the practice as we would like. This is especially true when it comes net types and how they impact fish health. Many people are under the impression that if the fish swims away it is healthy and ‘okay’. The reality is that we can’t always say for sure once they go back to their world and leave ours. In a study conducted by Teah Lizee and seven other scientists, they assessed the effects of various net mesh types on brook trout in, Quebec, Canada. 


Here is the skinny on the gear and methods used: 

The Gear

  •  Lightweight spinning rods.

  •  Barbed treble hooks on size 2 spinners.

    • Angling took place from boat, and 5 proficient anglers were constantly rotating to avoid any potential bias in data.

  • Compared large rubber mesh nets, knotless nylon mesh nets, knotted polypropylene mesh nets, rubber coated nylon mesh nets, and bare, wet hands.

    • Bare, wet hands were used to serve as a comparison tool for the 4 net mesh types.

From the above linked and mentioned study by Teah Lizee

From the above linked and mentioned study by Teah Lizee

The Methods

  • The anglers would fish and land 5 fish with each net type and then rotate to the next net type to avoid any potential bias.

  • Brook trout were dehooked in the boat with pliers (when necessary) and placed in a holding tank to observe any injury sustained from using the nets.

  • They measured mucus (slime) loss, scale loss, fin fraying, handling time, and dehooking time for each net type.

  • All brook trout were held in the tank for at least 1 hour for observation.

WHAT DID THEY FIND? Ranking of best to worst net types:

1. Large Rubber Mesh

  • Had the lowest amount of scale and mucus loss of any net type.

  • Caused some fin fraying (due to large mesh size that allows fins to protrude through the net). 

2. Rubber Coated Nylon Mesh

  • Caused some mucus and scale loss. 

  • Caused little fin fraying 


3. Knotless Nylon Mesh

  • Caused the highest proportion of scale loss.

  • Caused the highest proportion of mucus loss. 

  • Caused almost no fin fraying 

  • Dehooking and handling times were very long because the hook frequently got caught in the mesh of the net. This is the main reason we ranked it lower than the rubber coated nylon mesh.  


4. Knotted Polypropylene Mesh

  • Was the only mesh type found to cause significant fin fraying (5.2 times more than bare hands).

  • Caused little scale loss, but relatively high amounts of slime loss.

  • This net, the rubber coated nylon mesh net, and the large rubber mesh net all had very similar times for dehooking and handling.   


5. Bare, Wet Hands

  • Showed high proportion of scale and slimes loss (similar to the rubber coated nylon).

  • Caused very little fin fraying.

  • Brook trout were dropped much more frequently with bare, wet hands than any net mesh type.

  • Dehooking and handling times were the shortest for bare, wet hands.




  • Based on these results, large, rubber mesh nets are the least harmful to brook trout health, and the best available net type.

  • Knotted polypropylene mesh was the most harmful net type to brook trout health.

  • Although this study focused on brook trout, it also serves as a starting point for assessing net mesh type impacts on other salmonids as well as other species.

  • This study begs the question, who will manufacture a better net for fish?



Some Fresh Air on Air Exposure

By definition, fish live in water and with few exceptions (e.g., lungfish, arapaima) can only extract oxygen from water. As such, it should be no surprise that air exposure is not a “good” thing for fish. Of course, a little air exposure is not going to kill a fish. But what defines “a little”? The answer varies based on many factors. For example, some fish species are simply more tolerant to air exposure than others. Species like common carp and bullhead catfish are able to live in water with very little oxygen and therefore tend to also be fairly tolerant of air exposure — as much as 10 minutes of air exposure or more. And others (such as bluefin tuna, bonefish, and salmonids) are extremely sensitive to low levels of oxygen whether they are exposure to air or exposed to waters with little oxygen.

Sensitivity to oxygen can also vary for a variety of reasons for a given species. For example, water temperature influences how much air exposure a fish can withstand. For any given species, fish tend to be able to handle longer periods of air exposure at cooler temperatures than at warmer temperatures. Take bluegill sunfish for example — for a given duration of air exposure, the extent of impact to the fish is always lower for the cooler temperatures than it is for warmer temperatures, and the extent of that difference increases with longer periods of air exposure. Water temperature is SO important for fish that it is referred to as the “master factor” (See Finsights 14), and it affects all biological processes and is also the reason why some fisheries close when water temperatures exceed a given threshold. The closer the fish are to the upper end of their thermal tolerance range, the more important it is to minimize stress from air exposure. Sensitivity to air exposure can also vary depending on life stage. For example, Pacific salmon are quite sensitive to air exposure during early phases of their upriver migration yet when the approach spawning grounds (literally about to spawn), they become quite resilient to air exposure.

The idea that the context matters makes it very difficult to identify a single duration of air exposure to guide anglers in how to handle fish. The default should be “as little as possible”. We are unaware of a biological explanation nor a single scientific study showing that air exposure is good for fish. So, what is a “little”? If we are looking for a single number to apply across the board, the 10 second limit proposed in a synthesis of available data remains the most useful value. The Keepemwet Fishing mantra is about minimizing air exposure and keeping fish wet. Even we scientists love to admire fish and capture the moment just like anyone else. In fact, that was the entire premise for the #keepemwet movement — how fish can be admired in a way that also ensures that they are released in a state where there are likely to survive and thrive.

A couple of recent studies have been critical of the existing literature that suggests air exposure is bad for fish. Indeed, some of the older work was done in the laboratory for experimental purposes and some of those studies use absurdly long air exposure durations. Nonetheless, the patterns that emerged from those studies stand — and the patterns are clear — more air exposure is worse than less air exposure. There are some studies that have failed to demonstrate a negative effect of air exposure. For example, a recent press release from a study by researchers at the University of Idaho used the headline “brief air exposure not a threat to fish survival”. The air exposure durations used in that study were 30 and 60 seconds and involved adult cutthroat trout as they approached spawning grounds. The researchers revealed that there was no difference in survival or reproductive success for control fish (no air exposure) and those exposed to air. However, this study, just as many that have come before it, has its own limitations (e.g. they held the fish in tanks before simulating angling, which we know to be stressful,) and is very context dependent (e.g. survival is a whole different ball game when there are predators around). This context was absent from the press release and we are concerned that anglers and the angling media are left with the impression that “fish are tougher than we give them credit for” when in reality the message is that the impacts of C&R are varied and depend highly on species, location, how a study is performed. “Spinning” such findings to get media headlines does nothing to help improve how fish are handled by anglers. In fact, it does the opposite — it creates confusion. We greatly encourage all anglers to be careful and not take press releases such as this at face value.

We await a study that provides evidence that air exposure is good for fish — that it benefits them in a biologically meaningful way. There are many ways in which anglers can interact with fish and capture the moment forever without extending air exposure beyond 10 seconds. Let’s #keepemwet.

Happy Fishing! 
Dr. Steve Cooke, Dr. Andy Danylchuk, and Sascha Clark Danylchuk
 Keepemwet Fishing Science Ambassadors



The Nuances of Best Practices in Recreational Fishing

The Nuances of Best Practices in Recreational Fishing

by Dr. Shannon Bower

IMG_2089 (2).jpg

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.

Screen Shot 2018-12-06 at 8.49.27 AM.png

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.

Raja PK photo.

Shannon Bower 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

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

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%).


• 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.



ORVIS Fly Fishing Podcast with Sascha Clark Danylchuk

Featured this week on the ORVIS Fly Fishing Poscast is our very own Sascha Clark Danylchuk, Science and Operations Manager for KeepEmWet Fishing. Sascha is an angler and a scientist who has studied the effects of various catch-and-release techniques and has also kept up with the scientific literature on the subject. There is a lot of false and misleading information on the Interwebs regarding catch-and-release, and she sets us straight on a number of topics. I thought I was well-versed on this subject, but I learned a lot, and will modify my own practices in the future, based on our talk.



Keepemwet Fishing, Fisheries Research


At Keepemwet Fishing we believe that communication and knowledge sharing between the fisheries science and recreational angling communities is a two way street.   For example, anglers can learn more about fisheries science, and scientist can learn about the issues that are important to anglers and this can help inform their research.  We need this type of dialogue and interaction to make sure that catch-and-release is effective.   Scientists communicate and share their work and ideas through the publication of peer-reviewed articles in scientific journals, and so, here is our first contribution on Keepemwet Fishing to science literature.

"There is a growing body of catch-and-release (C&R) science showing that adjusting the way fish are caught, handled, and released can reduce impacts on individuals and populations. However, a major caveat is that C&R will be a more effective conservation tool if best practice guidelines stemming from the science are understood, embraced, and adopted by recreational anglers. In recognition of this, Keepemwet Fishing (KWF) has emerged as a nonpartisan movement to provide simple, clear, and accurate C&R guidelines that transcend species and subcultures within the recreational angling community". Full report here.



Bulkley Steelhead Catch-and-Release Project

Will Twardek photo

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.  



What Did They Say? Translating Presentations From the BTT Symposium Part 3

What happens to bonefish when there are sharks around?

Presentation by Robert J. Lennox
Carleton University


My happy place is wading a tropical flat for bonefish.  The subtle complexity of flats ecosystems fascinates me and the diversity of catchable species means that there could be another fish just beyond my sight line.  The predators that are often found on flats also keep things lively, but makes fishing and practicing catch-and-release a much more dangerous game for the fish.  

While there have been several studies examining the rate of mortality/predation of bonefish in the Atlantic, this is the first study to look at post-release predation in the Pacific on Albula glassodonta.  It’s also the first study to look at post-release predation in an area that is very sharky (why yes, that’s a technical term).  The small atoll in French Polynesia where this study was conducted has a huge abundance of blacktip reef sharks.  They follow anglers on the flats like puppies and it’s not uncommon to see over a dozen sharks on a single flat.  Understanding how bonefish fare in this type of situation is essential for our understanding of the impacts of catch-and-release.  

What did they do?

  • Study 1: caught bonefish and air exposed them for either 0, 10, or 30 seconds.  Released the fish with a small visual tracking bobber similar to those used in FINSIGHTS 5.  
  • Study 2: caught bonefish and either released them right away or placed them a recovery bag (originally developed for Atlantic salmon, and tested on bonefish in the Atlantic) for 30 minutes to let them rest after angling and see if they could reduce post-release predation rates.

What did they find?

  • Study 1: bonefish with no (0 seconds) of air exposure were much less likely to be attacked by sharks than those with 10 or 30 seconds of air exposure.  Bonefish (regardless of air exposure duration) were vulnerable to sharks for at least 20 minutes after release.  
  • Study 2:  Recovery bags did not help reduce the chance of post-release predation for bonefish.  
  • The authors hypothesize that the recovery bags were not effective because, despite the fact that the bonefish inside them were able to rest and be protected after angling, the sharks were still able to “smell” the bonefish and were attracted to the area.  Previous studies have shown that angled bonefish excrete stress hormones and that sharks are attracted these hormones.  

Why is this study important?

  • This is the first study to show that even 10 seconds of air exposure can significantly impact the post-release predation rates of bonefish.  
  • Despite the lack of effectiveness of the recovery bags used in this study, the idea of finding a way to help fish recover from angling, especially in areas with a lot of predators is definitely worth pursuing and could lead to the development of new techniques for the best practices for catch-and-release.   


A special thanks to Ed Anderson who donated the artwork accompanying these summaries. Thank you to the presenters and their collaborators for the work that contributed to these presentations, and for allowing us to represent them in these summaries.  Thank you as well to Natasha Viadero, Alora Myers, and Jordan Massie who provided assistance during the symposium.




What Did They Say? Translating Presentations From the BTT Symposium Part 2

Keepemwet Fishing and Bonefish & Tarpon Trust have teamed up to make the science that was presented at the BTT Symposium last November accessible to a wider audience.  A selection of presentations have been summarized and “translated” into non-technical language that is easily understood by non-scientists.  Several of the translations are below and more are available in the latest issue of the BTT journal.

What is in an angler’s control? Best practices for the catch-and-release of bonefish, tarpon, and permit

Presentation by Dr. Andy J. Danylchuk
UMass Amherst

Catch-and-release is commonly used a conservation tool for fisheries.  Whether it’s mandated or voluntary, it doesn’t take a rocket scientist to know that putting fish back in the water means that there will be more fish to catch tomorrow.  However, catch-and-release is only effective if most fish survive and are left with no permanent impacts.  Using best practices can help anglers achieve this goal.  

Keepemwet Tarpon by Ed Anderson

Keepemwet Tarpon by Ed Anderson

Best practices are actions that are often simple, and you have probably heard of many of them already, but together they have the potential to create better outcomes for fish that are caught-and-released.   You can think of best practices as catch-and-release version 2.0.  

Often when fisheries scientists study catch-and-release they look at the varying aspects of an angling event and how each contributes to the overall impacts of catch-and-release on an individual fish or a population.   Many parts of an angling event are in the control of an angler (e.g. hook type, duration of air exposure, how a fish is handled), while others anglers have less control over (e.g. water temperature, size of the fish).  The science on catch-and-release has not been conducted for all species and all aspects of angling, so while we can sometimes apply general best practices across species, it’s also important to acknowledge that species specific and location specific difference do occur.  

What do we know and what do we need to know?

While there are over a dozen studies conducted on bonefish (nearly all on Albula vulpes) catch-and-release, there has only ever been one study on tarpon and none conducted on permit catch-and-release.  

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Table of the studies that have been conducted on catch-and-release (Sci) for bonefish, tarpon, and permit, elements of the angling event, and their priority for future research (P).  Darker shades represent a higher priority.  Some studies covered multiple elements of the angling event.  De-predation refers to fish being attacked/eaten while on the line during the fight. 

From these studies we are able to form some specific best practice guidelines for bonefish such as:

  • Bonefish that roll or nose dive (called loss of equilibrium) are six times more likely be killed   by sharks or barracuda after release.  Air exposure is the main cause of loss of equilibrium.
  • Air exposure is more detrimental to bigger bonefish and at higher water temperatures.
  • Multiple studies on bonefish have shown that longer handling times increase stress levels in fish and can lead to poorer outcomes after release.  
  • Fish barbless hooks.  If a bonefish is deeply hooked cut the line instead of trying to remove the hook.  
  • Don’t use lip grippers on bonefish.  A study found that they can cause significant damage.

Until more science can be done on tarpon and permit, it behooves us to use some of what we know from bonefish and other species when fishing for tarpon and permit, such as:

  •  Reduce/eliminate air exposure
  •  Minimize handling
  •  Rethink the “Hero Shot”

Eventually, filling in the gaps in our understanding about how tarpon and permit respond to catch-and-release will enable us to create best practices for all flats fish. 


A special thanks to Ed Anderson who donated the artwork accompanying these summaries. Thank you to the presenters and their collaborators for the work that contributed to these presentations, and for allowing us to represent them in these summaries.  Thank you as well to Natasha Viadero, Alora Myers, and Jordan Massie who provided assistance during the symposium.



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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

Concept diagram Reflexes.jpg

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.



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Bonefish Restoration Research Project Induces Spawning in Wild Bonefish

January 8, 2018

Contact: Nick Roberts

Director of Marketing & Communications

Managing Editor, Bonefish & Tarpon Trust Journal 

Bonefish & Tarpon Trust

Coral Gables, FL— The Bonefish Restoration Research Project (BRRP), a major initiative sponsored by Bonefish & Tarpon Trust, has successfully induced spawning of wild bonefish and hatched the fertilized eggs into larvae. This is a first for this species, and a major step in the organization’s efforts to spawn and raise bonefish in captivity. 

The project, which is based at Florida Atlantic University’s Harbor Branch Oceanographic Institute, achieved this milestone during field experiments earlier this month in the Bahamas. A team led by Dr. Jon Shenker of the Florida Institute of Technology and Dr. Paul Wills of FAU-HBOI successfully used reproductive hormone injections to induce final mature eggs in a female that had been captured from the wild in a pre-spawning state of development. The female was stripped spawn and the eggs fertilized by a stripped spawned male, which resulted approximately 24 hours later in live bonefish larvae.

“We now know that we can indeed get bonefish to spawn in captivity,” said Dr. Shenker. “This success will help us optimize methods to induce spawning of fish brought in from the natural habitat, and to spawn fish maintained for a long time in a controlled aquaculture facility. Our newly-hatched larvae will also enable us to start learning how to culture these very unusual leptocephalus (“slender head”) larvae.”

“Observations of development and behavior of bonefish larvae will also indicate critical habitat and larval drift characteristics needed for refining oceanic models of larval dispersal that other Bonefish & Tarpon Trust research has developed,” added Dr. Paul Wills. “We are gaining a wealth of information about the biology of this species from this one successful spawn and future spawns will only yield more.”

Through BRRP, Bonefish & Tarpon Trust, in collaboration with the National Fish and Wildlife Foundation (NFWF) and Florida Atlantic University’s (FAU) Harbor Branch Oceanographic Institute, is seeking to pioneer the methods of spawning and rearing bonefish in captivity as a means of providing fish to replenish the Florida Keys bonefish population as part of the broader restoration strategy. The primary goals of the five-year-long program, which began in mid-2016, are to learn how to spawn bonefish in aquaculture systems, rear the resulting larvae and juvenile fish, and ultimately help target habitat restoration efforts in the Keys ecosystem.

Bonefish are integral to Florida’s travel and tourism industry. It is estimated that bonefish, tarpon and other species in the ‘flats fishery’ contribute more than $465 million to the economy in the Florida Keys. 

“This is a great step forward in our research and development of methods to rear bonefish in captivity,” said BTT President Jim McDuffie. “Our team was able to produce eggs and larvae from wild bonefish that had not gone through the species’ usual spawning behaviors in the wild. Ultimately, success in this project will give us another tool in our toolbox as we work to restore the bonefish population in the Florida Keys.”




FINSIGHTS #14 Brian O'Keefe photo

FINSIGHTS #14 Brian O'Keefe photo

Finsights #14 – Why is water temperature so important?

by Sascha Clark Danylchuk

It’s been a particularly warm autumn here in New England. Usually we would be at peak fall foliage about now, but I still see mostly green out my window. As someone who would take heat over cold any day you won’t catch me complaining about our delayed progression towards winter, but it has gotten me thinking about temperature and, in particular, the importance of water temperature for fish.  

Google fish and water temperature and you’ll find a plethora of pieces on the optimal water temperature for different species of fish. There are graphs, tables, and lengthy articles written on the subject. Many anglers are aware that high water temperatures are not good for fish (think of hoot owl restrictions, daily closures between 2pm and midnight, and fish kills in the summer) and it’s all related to the role water temperature plays on fish biology.  

Almost all fish are cold blooded, with rare exceptions such as tuna and opah. They are ectotherms, which means that their body temperature is a direct result of the temperature of the environment (water), and poikilotherms meaning that water temperature varies and thus so does their body temperature. Each species of fish has an optimal water temperature (an ideal temperature for living and proper functioning) as well as a critical thermal maximum and minimum (temperature beyond which vital bodily functions break down and that can lead to death).  

Finsights #14 v3mr.jpg

Being poikilothermic ectotherms means that many of a fish’s body systems are influenced by water temperature. In fact, water temperature is often referred to as the “master factor” when it come to fish. The rate of metabolism, the chemical process that converts food to energy, is highly dependent on temperature. In general, for every 10 degrees Celsius that water temperature increases, a fish’s metabolic rate doubles. This means that at warmer water temperatures, fish have a faster metabolism and need more food. It also means that at warmer water temperatures fish need more oxygen, a critical component of the metabolic process. However, all else being equal, warmer water holds less oxygen than colder water.  

A number of studies have demonstrated that water temperature impacts the survival and recovery of fish from angling, but most of the time those studies didn’t directly consider water temperature. This study specifically examines the effect of water temperature on angled fish.

What did they do?
    •    They used bluegill in this study because they were easy to catch and typically live in water with dramatic temperature variations.
    •    Fished at three different water temperatures (low = 18.3°C/64.9F, medium = 22.8°C/73F, high = 27.4°C/81.3F)
    •    At each temperature, after angling they air exposed fish for different durations from 0 seconds to 16 minutes (yes, 16 minutes is a very long time and not very realistic, but most of the times were less than 2 minutes and they wanted to see what happened at an extreme).  
    •    Time to recover, immediate and delayed mortality (up to 48 hours after angling) was measured for each fish.

What they found:
    •    Time to recover increased significantly as water temperature increased.
    •    Almost no immediate mortality at any temperature.
    •    Delayed mortality was highest (nearly 40% of fish died) for the high water temperature. Also, more fish died and died faster with more air exposure at the high water temperature.  
    •    No fish died at any water temperature with 0 seconds of air exposure.  

Why is this study important for anglers?
    •    This study underscores that stressors to fish (caused by angling or otherwise) are interactive and/or cumulative, especially when it comes to water temperature.
    •    At higher water temperatures remember that fish need more oxygen (but the water might actually contain less oxygen) and fish take longer to recover from angling.
    •    Food for thought, how might climate change affect fish and fishing? Will fish be able to adapt to warmer water temperatures? Will we see more fishing closures as summers get hotter? Are you already starting to see climate change impacts on your home water?  

Happy fishing!
Sascha Clark Danylchuk





Finsights #13    Can you revive fish?

by Sascha Clark Danylchuk


FINSIGHTS #13 Can You Revive Fish?

FINSIGHTS #13 Can You Revive Fish?

I would guess that most anglers have heard of, if not performed, revival techniques for fish. If you haven’t, it’s the practice of holding fish into the current or moving them in the water before letting them go to help them get more oxygen and recover from the exhaustion of angling. When I first heard about this I was encouraged to move fish forward and backward in the water. This technique was soon replaced with an “only forward” or “figure-eight” method. But why and how have these techniques become part of our catch-and-release tool kit?

Just like us fish need oxygen, but unlike us they get it from water. On each side of the back of their throat most fish have four gill arches, which are curved, bony structures. Attached to each gill arch are two rows of filaments. Each filament has thousands of lamellae, which are like tiny plates and provide the surface for gas exchange. While water flows one way past the lamellae, blood flows in the opposite direction and this countercurrent exchange allows fish to absorb oxygen and expel carbon dioxide.  

The important part of this to remember is that water needs to flow in one direction for fish to respire effectively: water goes in the mouth, over the gills, and out the operculum (gill cover).  


Copyright © 2009 Pearson Education

Copyright © 2009 Pearson Education

If my description and the diagram still leave you confused check out this video:

Based on this explanation of gill function, it seems completely logical that you could revive a fish after angling and help it get more oxygen by increasing the amount of water that flows over the gills, right? You wouldn’t be alone if you said yes; many websites, guides, anglers, and fishing organizations encourage anglers to revive fish like this prior to release.

But, how well do these techniques actually work?  A couple of scientific studies give us insights into the effectiveness (or lack thereof) of such revival techniques.  

Salmon in Rivers:
The first study was performed in a lab, but because labs aren’t always realistic enough the scientists also did a similar study in a natural setting, and it’s the latter study that I’m going to focus on here. Using Fraser River sockeye salmon caught with a seine net (a large, soft net that is commonly used as a non-angling way to capture fish) and via angling, the scientist examined whether assisted ventilation (facing fish into the current for one minute) after air exposure had any effect on the survival, movement, and ability of the fish to reach natal spawning grounds.  

The scientists found no benefit of reviving fish when looking at movement and survival following release.

Bass and Trout in Lakes:
Here’s a pair of good sciencey words: lentic refers to still, fresh water such as a lake or pond. Whereas lotic refers to moving, fresh water as in a stream or river.

The third study examined largemouth bass and brook trout in lentic systems. The scientists compared three groups of angled and air exposed fish: group 1 fish were immediately released, group 2 fish were moved back and forth in the water for revival, and group 3 fish were moved in a circular or figure-eight motion for revival.  

Jake Brownscombe photo.

Jake Brownscombe photo.


As with the previous studies in lotic systems, the scientist found no benefit of either methods of revival for fish in lentic systems; neither form of assisted ventilation led to faster revival for largemouth bass and brook trout.  

Why can’t you revive fish using these methods?
Despite the intuitiveness of revival techniques, these studies showed that they didn’t help fish. Why not? Here are a couple educated guesses from the authors and other experts:
    •    Holding fish causes them some stress regardless of what you are doing to them. Therefore, holding fish longer by trying to revive them counteracts any benefits they might receive.
    •    Most species of fish, including sockeye salmon, largemouth bass, and brook trout, can respire on their own by opening and closing their mouth and opercula. After angling, they typically do this and are already maximizing oxygen uptake. Anything we as anglers try to do to help them get more oxygen doesn’t actually make enough of a difference.

Why is this important for anglers?
Despite our best intentions, letting fish go as soon as possible is probably the best thing we can do for them. Any fish that can swim away should be released and doesn’t need to be revived. We probably are not harming fish by trying to revive them (none of the studies showed any detriment to fish that were revived), but we likely aren’t doing them any favors either.  

Of course as with any rule of thumb, there could be a few caveats to this recommendation depending on the species of fish, situation, and location. For example, if a fish cannot swim away, reviving it could be beneficial. Similarly, in an area with predators it is possible that holding fish longer and reviving them gives them a better chance of escaping post-release predation attempts. But, more studies need to be done to assess these situations.

For now, the research suggests that there is no benefit to reviving fish, that we shouldn’t hold fish longer than necessary, and that letting them go when they are ready to go is ideal.

Happy Fishing!
Sascha Clark Danylchuk




Keepemwet Fishing Science Advisor Dr. Andy Danylchuk.

Keepemwet Fishing Science Advisor Dr. Andy Danylchuk.

Via American Fisheries Society

Tampa, FL) August 23, 2017 – Dr. Andy J. Danylchuk, an Associate Professor of Fish Conservation at the University of Massachusetts, Amherst, received the award for Excellence in Public Outreach today at the 2017 American Fisheries Society (AFS) Annual Meeting in Tampa, Florida. AFS President Joe Margraf presented the award at the meeting’s plenary session. The award for Excellence in Public Outreach is presented to an AFS member who goes the "extra mile" in sharing the value of fisheries science/research with the general public through the popular media and other communication channels.

“We applaud the distinguished contributions of Dr. Danylchuk and thank him for his continuous efforts to share the value of fisheries science and research,” said AFS President Joe Margraf.

Dr. Danylchuk is the Scientific Advisor for the KeepEmWet Fishing initiative (, where he has been working with vast networks of recreational anglers, as well as industry and media partners, to effectively communicate best practice guidelines for catch-and-release.  He is also the co-chair of the science and policy committee of the American Fly Fishing Trade Association.

Dr. Danylchuk has made three documentary films that have all been finalists in the prestigious BLUE Ocean Film Festival. Some of his films have also been distributed on PBS, and are available on various platforms for educators and the general public. His second film, Raising Shrimp, had its Canadian Premiere at the 2015 AFS annual meeting in Quebec City.

Dr. Danylchuk frequently writes articles for conventional popular media outlets and blog posts that are widely shared, especially within the recreational fisheries community. He is also an ambassador for several recreational fishing companies, including Patagonia.

About AFS: Founded in 1870, the American Fisheries Society (AFS) is the world’s oldest and largest fisheries science society. The mission of AFS is to improve the conservation and sustainability of fishery resources and aquatic ecosystems by advancing fisheries and aquatic science and promoting the development of fisheries professionals. With five journals and numerous books and conferences, AFS is the leading source of fisheries science and management information in North America and around the world.




Finsights #12- An interview with Sascha Clark Danylchuck

No better way to start a day than with coffee and a rod on your home water. Andy Danylchuk photo. 

No better way to start a day than with coffee and a rod on your home water. Andy Danylchuk photo. 

KWF- Give us a brief bio, background including why you are focused on fish, fish habitat and conservation.
SCD- I grew up in a family where my parents were in constant disagreement about the ideal vacation spot – one preferred the mountains, the other the beach.  We were lucky enough to spend time in each setting and it was mostly through those experiences that water, and nature in general, became deeply ingrained in my identity.  

I didn’t really start fishing until after college when I moved to the Turks and Caicos Islands to work as a research assistant at a marine science field station.  My brother built me a fly rod, and I taught myself to cast with flies I tied myself.  Needless to say it was many months before I caught anything, but wading flats gave me a whole new perspective and appreciation for the ocean, and I was smitten.  

While I knew that I wanted to pursue a career focused around science and water early on, my focus has shifted within those boundaries over the years.  I’ve come to realize that a multidisciplinary, multipronged approach is necessary to make a significant difference when it comes to helping recreational fishing become more sustainable.  

KWF- What's your favorite fishing memory?
SCD- Watching my daughter out-fish her older brother, my husband, and myself on the Madison.  She claims it was due to her “good luck shorts” (which have fish on them), but she’s developing into a badass little angler.   

KWF- How about your bucket list trip or fish species to catch?
SCD- Arctic grayling.  I recently spent time in a remote corner of Argentine Patagonia and it renewed my excitement about salmonids.  I’d love to head to the other end of the Americas to fish for grayling.  

Sascha and kiddos in Argentina on their recent Fish Mission. Andy Danylchuk photo.

Sascha and kiddos in Argentina on their recent Fish Mission. Andy Danylchuk photo.

KWF- Tell us about your most recent fishing trip.
SCD- I just returned from seven months of traveling.  My husband had a sabbatical so we pulled our kids out of school and took off on a three-part Fish Mission.  We started in Argentina living in a 400 square foot cabin for two months.  We spent time hanging out with the phenomenal crew from Las Pampas Lodge and fished some of the most beautiful water I’ve ever seen.  I landed my personal best rainbow, a 24-inch beauty, on a day so windy that downwind was the only direction I could cast (not that I’ve ever been skilled at casting into the wind).  

Next we were in the Florida Keys for a couple months.  I lived there almost 10 years ago and it was fun to visit old haunts and see friends.  I still, however, have yet to land a permit…

The final part of our Fish Mission was a three-month camping trip from Florida to Massachusetts the long way – first heading west to CA, then north to British Columbia, and finally east back to New England).  I designed and my husband and I built a trailer that had a kitchen, but we tented it the whole time – even in 19oF thundersnow (yes, it exists) at the Grand Canyon, which is not an experience I feel the need to repeat anytime soon!  We had planned to do a lot of fishing along the way, but the huge snowpack in the west last winter meant that many of the rivers were still too high to fish well.  Getting to spend so much time outdoors, however, made up for the fishing we missed.   

Sascha fishing in the Bahamas. Andy Danylchuk photo.

Sascha fishing in the Bahamas. Andy Danylchuk photo.

KWF- Why volunteer with KWF? Hopes for the future of the movement?
SCD- There is a fracture between science and conservation in recreational angling, especially when it comes to best practices.  I believe that anglers want to do the right thing, but I don’t think that they always get a clear message from scientists about what exactly the right thing is.  KeepEmWet is the much-needed link that can engage anglers and scientists directly, create information flow in both directions, and move all of us towards being better stewards of our finned natural resources.  

KWF- If you were a fish, what species would you be and where would you live?
A bonefish on the flats, of course.  My happy place is wading a tropical flat, it makes no difference whether it’s in the Caribbean or the Pacific –  it’s always where I would rather be.  





Finsights #11– 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.

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.

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.




Finsights #10 Lip gripping devices and your catch. Tiger fish. Dave McCoy photo.

Finsights #10 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.

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




Finsights #9– How do you handle fish? Paul Moinester/Keepemwet Fishing photo.

Finsights #9– 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.

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