Fish reflex tests - a valuable tool for anglers

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

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

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

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

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

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

1. Escape response

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

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

2. Righting response

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

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

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

3. Regular ventilation

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

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

4. Eye tracking

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

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

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

The Science:

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

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.

19 hours post fertilization - the embryo is wrapped around a transparent yolk sac, with bubbles of oil on top of the embryo (oil for floatation and energy) Photos courtesy of Dr. Jon Shenker

25 hours post fertilization - the embryo has developed to the point that the tail is now free from the tight circle where it was initially attached. Photos courtesy of Dr. Jon Shenker

0 hours post hatching (= 26 hours post fertilization) - the backbone and bands of muscle are evident along the body; the beginning of the eye is at the left. The oil droplets have coalesced into a single large droplet of oil by the belly of the larva. The transparent structure covering almost the entire bottom of the larva is filled with transparent yolk that will fuel growth until the larva develops its eyes, gut, mouth, etc. Photos courtesy of Dr. Jon Shenker

“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.”

THE IMPORTANCE OF WATER TEMPERATURE

Brian O'Keefe photo

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).  

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

CAN YOU REVIVE FISH?

Can you revive fish?

by Sascha Clark Danylchuk

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

If my description and the diagram still leave you confused check out this video:
https://www.youtube.com/watch?v=XEIRlw5rCUk

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.

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

DR. ANDY J. DANYLCHUK RECEIVES AWARD FOR EXCELLENCE

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 (https://www.keepemwet.org), 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.

An Interview with Sascha Clark Danylchuk

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.

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.

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.

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.  

When scientists get together to talk fish

When scientists get together to talk fish

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

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

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

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

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

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

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

Happy Fishing!
Sascha Clark Danylchuk

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

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

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

Read full report here.

Lip Grippers

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

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

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

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

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

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

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

Happy Fishing!
Sascha Clark Danylchuk

Fish Slime

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

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

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

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

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

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

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

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

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

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

See the complete study here.

Happy Fishing!
Sascha Clark Danylchuk

The Science of Catching more Fish

By Sascha Clark Danylchuk

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

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

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

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

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

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

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

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

Read the entire review paper here.

Happy Fishing!
Sascha Clark Danylchuk

Fish vulnerability by Robert Lennox.

“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 2

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

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

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

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

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

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

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

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

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

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

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

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

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

Happy Fishing!
Sascha Clark Danylchuk

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

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

The "grey ghost" Alex Filous photo.

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

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

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

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

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

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

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

Read the full study here.

Happy Fishing!
Sascha Clark Danylchuk

Fish Can get Stressed Too

Fish can get stressed too

By Sascha Clark Danylchuk

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

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

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

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

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

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

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

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

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

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

Happy Fishing!
Sascha Clark Danylchuk

A classic air exposure paper

A classic air exposure paper

by Sascha Clark Danylchuk

Rainbow trout resting before release. Bryan Huskey photo.

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

Happy Fishing!
Sascha Clark Danylchuk

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

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

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

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

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

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

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

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

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

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

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

Happy fishing!
Sascha Clark Danylchuk

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

Parts of a Scientific Paper

By Sascha Clark Danylchuk

Taking a non-lethal blood sample from a bluefin trevally in French Polynesia. Photo provided by author.

Read post #1 Introduction to Finsights here.

The writing style of scientific manuscripts makes many people cringe. The use of the passive voice (scientists rarely use “I” or “we”) and the density of the writing can make scientific papers difficult to follow. Similarly, discerning the important aspect of the study can be tricky because scientists go to extremes to avoid adjectives and subjectivity and almost everything written is given equal credence. I’ve put together a brief description of the major parts of a scientific manuscript and what to look for in each section for improved comprehension.

Abstract: brief summary of the study and its findings. This is the place to start to see if a paper might be relevant and interesting.

Introduction: background of pertinent previous studies, and goals and hypothesis for the present study. From the introduction you should understand the motivation for the study.  It’s also a great place to find references to other studies that might be of interest.

Methods: a description of the study process, with enough detail so that another person or research team could replicate it. This can be very dry, and it’s supposed to be that way.  

Results: a description of the findings and the results of statistical analyses. This can be confusing unless you have a good grasp of statistics. Look for terms like “statistically significant” to recognize what is important. The figures and tables (graphs, maps, and diagrams) will also highlight notable trends and findings, however there is a definite skill to figuring out what is scientifically meaningful.

Discussion: an objective interpretation of the results and statistics, and how the findings add to our understanding of the subject matter. A good discussion should key in on the results that are the most meaningful. The discussion also often covers the limitations of the study, which are important for understanding how broadly the findings can be applied (e.g. does this apply to all trout, only brook trout, or only brook trout in New York?).

Keepemwet Fishing Science Advisor Andy Danylchuk and field assistant Kim Ovitz doing work on Golden Dorado in Northern Argentina. Tyler Gagne photo.

When I read a manuscript, I usually spend most of my time on the abstract, introduction and discussion.  It’s these sections that get to the core of the subject matter and provide most of the type of information that an angler would find interesting.  

Lastly, it’s important to remember that each study and corresponding manuscript is an incremental step in addressing a large subject matter. Rarely can any one study tackle all questions, but put together, over time, scientists strive to find complete answers to complex problems.

Happy fishing!
Sascha Clark Danylchuk

Science Notes from John McMillan

Chrome steelhead via John McMillan Instagram @rainforest_steel.

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

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

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

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

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

Introduction to Finsights

By Sasha Clark Danlychuk

I have been seeking water for as long as I can remember. As a child, it was the beach or a mountain stream in which to play. Eventually, I began to search for the creatures living in the water and it was no great surprise that this led me to become a fisheries scientist. I still love to play in the water, and more often than not, that involves fly fishing.

The author Sascha Clark Danylchuk cradling perfection in the form of a bonefish.

More and more, however, I find the intersection between my work as a fisheries scientist and my passion as a recreational angler to be messy and convoluted. I admire that innate conservation ethic exhibited by many anglers, but find the lack of scientific backing to their practices frustrating. Likewise, I appreciate my colleagues’ quests to solve issues and find sustainable solutions, but I am aggravated that their ideas rarely make it past esoteric scientific publications.

In my quest to clarify fisheries science to recreational anglers, and to encourage scientists to make their work accessible to a wider audience I have teamed up with Keepemwet Fishing for a blog series I am calling Finsights in which I will “translate” some of the most important scientific studies on recreational angling so that they can be understood by more people.

But, let’s begin with the scientific publications process and why scientists write in such a complex, dense, and let’s face it, dull style. Scientific publications were developed as a means for scientists to make their work known and judged objectively. The process of publication requires a scientist (or, more often than not, the group of scientists) involved in a study to write a manuscript, which follows a very specific format, and to submit the manuscript to a journal of their choosing. There are hundreds of journals, and they vary in subject matter as well as quality. Once a manuscript is submitted it is read by an editor or associate editor who then must find 2-3 anonymous peers to also review the manuscript and decide if it is worthy of publication. Publications are reviewed based on the quality and merit of the study as well as quality of writing. If the manuscript is accepted (usually after some revisions are made) it is published. If it is rejected, the authors can submit it to another journal and try again. Throughout this entire writing process the goal is precision; the writing has to be absolutely accurate and the wording extremely precise, making the journal articles both dense and generally dull (no flowery adjectives or subjectivity allowed!).  There is also a limit to how much the authors can extrapolate their results.

Almost too scenic to fish. Sascha stream side in Patagonia.

The advantages of this process is that there is an ongoing body of literature which has been judged as sound and provides the basis of further study for any given scientific subject. The number and quality of peer-reviewed publications has also become the standard by which scientists are evaluated.

The disadvantages are that the whole process (from submission to publication) can take months to years, meaning that by the time one study is published the scientist is often working on the next study. Also, you cannot publish a study in more than one journal, and authors of manuscripts are not paid for their publications, if anything they pay the journal to publish their work.

The realities of the peer-review process can also hinder publication. Not only is it often difficult for editors to find reviewers for a manuscript (reviewers volunteer their time and it can take many hours to properly review a single manuscript), but I have also heard many stories of manuscripts that were rejected because an editor failed to find a peer-reviewer who was a true peer and adequately understood the subject matter of the manuscript.  The manuscript can also be rejected based on the challenge to adequately communicate the science, or that the science simply wasn’t ‘up to snuff’.

Submerged brown trout. Bryan Huskey photo.

Next time I’ll go through the major sections of a scientific paper and provide some hints for discerning the important bits and finding the ‘highlights’ that are important to anglers interested learning more about the fish they are after.

Happy fishing!
Sascha Clark Danylchuk