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Keepemwet Ambassador


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

What happens to bonefish when there are sharks around?

Presentation by Robert J. Lennox
Carleton University


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

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

What did they do?

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

What did they find?

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

Why is this study important?

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


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





Finsights #12- An interview with Sascha Clark Danylchuck

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

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

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

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

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

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

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

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

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

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

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

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

Sascha fishing in the Bahamas. Andy Danylchuk photo.

Sascha fishing in the Bahamas. Andy Danylchuk photo.

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

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





Finsights #6 – “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.

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.

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.

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




Science Notes from John McMillan

Chrome steelhead via John McMillan Instagram @rainforest_steel.

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