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Catch & Release

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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:

 

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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.

 

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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.

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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

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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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FINSIGHTS- TRANSLATING THE SCIENCE OF FISHERIES REPORTS #11

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.

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

 

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FINSIGHTS- TRANSLATING THE SCIENCE OF FISHERIES REPORTS #9

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

 

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Finsights- translating the science of fisheries reports #5

Finsights #5 – “I saw the fish swim away so it must be fine” - Part 1

The "grey ghost" Alex Filous photo.

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.

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 original report here.


Happy Fishing!
Sascha Clark Danylchuk

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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.

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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.

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Best practices for catch-and-release recreational fisheries – anglingtools 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.

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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

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April Vokey's "ANCHORED" Podcast featuring Andy Danylchuk

Join well known angler, April Vokey, as she interviews some of the most influential people involved in the fishing world today. Learn more about their careers, opinions, history, relationships, and life both on and off the water. Click to play podcast.

Dr. Andy Danylchuk is a professor at the University of Massachusetts Amherst, a passionate angler, and a fellow fly fishing ambassador for Patagonia clothing.  His work covers both marine and freshwater systems, with a primary focus on stress physiology, behavioural ecology, spatial ecology, predator-prey interactions, and adaptations in life history as a response to disturbance.  Andy has been at the forefront of revolutionary science in the Bahamas, and is now currently spearheading a program taking place in Northern BC.  I met with Andy during his time up north to see if I could learn about the project that had so many people around me abuzz.

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Influence of hook type and live bait on the hooking performance of inline spinners in the context of catch-and-release brook trout Salvelinus fontinalis fishing in lakes

The objective of catch-and-release angling is for the fish to survive with minimal fitness consequences. However, fish survival can be compromised by a number of factors, especially anatomical hooking location. To evaluate whether hook type or bait influence hooking outcomes, we tested different combinations of hook (treble or single siwash hooks) and bait (hook tipped with worm or no worm) while angling for brook trout (Salvelinus fontinalis) with inline spinner-style fishing lures. Read More.

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Characterizing information on best practice guidelines for catch-and-release in websites of angling-based non-government organizations in the United States

Recreational catch-and-release angling is an important tool for managing fish stocks. As recreational fishing is often a culturally or community-based activity, many anglers look to local grassroots and other non-government organizations (NGOs) as a source of information regarding their angling practices. Read More.

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