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

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.  

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. 

Acknowledgements

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.

“I saw the fish swim away so it must be fine” - Part 3

“I saw the fish swim away so it must be fine” - Part 3

Robert Lennox Photo

My last two posts have been about the range of possible lethal and sublethal impacts of catch and release angling on fish, and I want to round out the discussion with one last post. When it comes to sublethal effects, it’s fairly easy to comprehend the direct consequences of angling on an individual fish. What can be more difficult to understand and discern scientifically is how angling could impact an entire population of fish.

One way to get at population level effects is to examine how angling impacts the fitness of fish. Keepemwet Science Ambassador John McMillan recently provided a nice explanation of what fitness means for fish - the ability of an individual to contribute viable offspring to the next generation.  So, a decrease in fitness would be a decrease in the number or the quality of offspring from a given fish.

Anglers landing an Atlantic salmon. Robert Lennox photo.

A scientist releasing a studied fish. Robert Lennox photo.

The research paper for this blog post specifically looked at whether catch and release angling impairs fitness. The scientists were able to take advantage of the unique geography of a small river in Quebec, Canada that also contained a fish ladder, which allowed for a complete inventory of Atlantic salmon that entered the river to spawn. Every fish that entered the river was sampled for their genetic makeup. Genetic samples of fish are most frequently obtained by cutting off or punching out a very small piece of fin (it doesn’t bleed and quickly grows back).  

Atlantic salmon in the river. Robert Lennox photo.

What did they do?
    •    All salmon entering the river at a fish ladder were genetically sampled and their length measured.
    •    All anglers on the river were asked to fill out a questionnaire and take a genetic sample of each fish they caught and released.
    •    The following year, fry (baby salmon) were sampled in the river to determine parentage.

What did they find?
    •    20% of the salmon in the river were angled and were the parents of 22% of the offspring. This means that the fish that were caught and released were able to spawn.
    •    Larger angled salmon produced significantly fewer offspring than non-angled salmon, however, there was no difference in number of offspring (in angled vs. non-angled fish) for smaller salmon.
    •    Air exposure decreased the fitness of salmon.  Depending on water temperature, the reproductive success was 2 to 3 times lower for angled salmon that were air exposed versus those that were not.  

Why is this study important to anglers?
    •    Once again, we see that air exposure is bad for fish. In this case, it’s bad for the next generation of fish.  
    •    All fish are not equal – larger fish can be more susceptible to the sublethal effects of angling. This is true when it comes to fitness, as well as when it comes to stress (link to Finsights #4). As anglers, we need to treat the larger fish that we pursue with the utmost care and respect.  Angling can impact large fish in more ways than it does smaller fish and therefore we have an extra duty to Keepemwet.

Link to full research paper.

Happy Fishing!
Sascha Clark Danylchuk

SCIENCE NOTES FROM JOHN MCMILLAN

Wild steelhead image from Keepemwet Science Ambassador John McMillan.

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

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

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

The "grey ghost" Alex Filous photo.

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

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

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

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

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

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

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

Read the full study here.

Happy Fishing!
Sascha Clark Danylchuk

Fish Can get Stressed Too

Fish can get stressed too

By Sascha Clark Danylchuk

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

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

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

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

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

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

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

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

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

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

Happy Fishing!
Sascha Clark Danylchuk

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.

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.