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FINSIGHTS- TRANSLATING THE SCIENCE OF FISHERIES REPORTS #4

Finsights #4 – 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.

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.

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 report: 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

 

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Finsights- Translating the Science of Fisheries Reports

Introduction to Finsights- 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.

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.

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.

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

 

 

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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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