Fishing Parkland Shorelines - Be aware of barotrauma in fish

Welcome to Week CXCVIII of ‘Fishing Parkland Shorelines’. Like most of us I am a novice fisherman, loving to fish, but far from an expert. In the following weeks I’ll attempt to give those anglers who love to fish but just don’t have access to a boat, a look at some of the options in the Yorkton area where you can fish from shore, and hopefully catch some fish.

A situation that is being discussed more and more in the fishing fraternity is barotrauma.

“Simply stated barotrauma is “injury caused to the body by changing air or water pressure.” In humans we know this as “The Bends”- a dangerous condition that divers experience when they come up too fast from deep water. Believe it or not, the same thing happens in fish,” notes www.rebeccaeberts.ca.

“For example: when we angle walleye at the bottom of the lake, those walleye have a certain amount of pressure on them from above. When we yank them up on our line, suddenly all that pressure about them is reduced. This means that their gas filled cavities suddenly expand as they are no longer compressed. This is particularly a problem for fish as they have swim bladders. The swim bladder is a balloon like organ that they use to regulate buoyancy. They expand it to move up in the water column, and remove air from it to move deeper in the water column. Unfortunately when we pull these fish up from deep depths they are unable to regulate that swim bladder. Barotrauma is most commonly known for its prevalence in deep sea fish (e.g. rock fish), however it is also a problem for a fresh water fisheries including in our Saskatchewan lakes.”

It happens that Rebeca Eberts is becoming a great source of information on the condition in Saskatchewan fish. She is currently studying barotrauma in catch and release fish in Saskatchewan, which fisherfolk can become involved with through a survey on the mentioned website.

I first heard of the work when Eberts spoke at the Saskatchewan Wildlife Federation Convention held in Yorkton recently, and of course quickly did some additional research on her site, and with credit included much of her info ration here because I believe we fisherfolk need to be aware of the condition, and also how best to deal with it.

“Well the 86th annual Saskatchewan Wildlife Convention was an amazing experience, as is every SWF convention I’ve been too,” she wrote on the site. “This one was particularly inspiring as I spoke on an issue that most anglers have encountered, but many may not understand fully. I am talking about barotrauma in fish. Now first off I’ll let you all know that I am by no means a barotrauma expert, as I am a fish ecologist not a fish physiologist. However, I was concerned about it, and did my homework, compiling every bit of information I could on the topic.”

In regards to who Eberts is, she is currently a graduate researcher at the University of Regina, Saskatchewan working on her Masters’ in biology.

“Although located in the prairies, my research focuses on the ecology of whitefish in the Great Lakes. This means I have had the chance to travel to and from the Great Lakes, experience some beautiful places and meet some pretty amazing people. I currently work out of Christopher Somers’ Wildlife Ecology & Genetics Lab,” she writes.

“As you may have suspected, my interest in research was sparked by a love for fishing. Besides keeping me sane through graduate school, my love of angling has also brought me to some beautiful places and to some spectacular fish. I thoroughly enjoy any public outreach which unites anglers and researchers towards a common goal. Please visit my resources tab to check out some of the material I have presented to anglers.”

But back to barotrauma.

In the immediate Yorkton area most waters, beyond occasional pockets will not be 30-plus-feet deep.

But we all fish deeper waters at time. I can recall lake trout fishing at Whelan Bay on Whiteswan Lake up the Hanson Lake Road when I was years younger, and those fish were in very deep water, and I never recalled issues like barotrauma, but then Eberts explained not all fish are affected in the same way.

Symptoms of barotrauma vary depending on the species.

“Physoclistous species are fish with swim bladders that are not connected to their mouth,” she details on her website. “These include your perch, pike and walleye. The only way these fish can remove the excess gas trapped in their swim bladder (and other tissues) is by slowly diffusing it out of the swim bladder through their blood. When we bring these species up from deep water they often have a characteristic protruding stomach from their mouth. This is because their swim bladder has expanded so large that it has pushed other organs, like the stomach, out.

“These fish may also have “bubble eyes”, and bloating elsewhere throughout their body. Physostomous species, such as your carp, trout and salmon are those which have a direct connection between their swim bladder and mouth.

“This means they can remove some of this excess air by burping it out. You may have heard your lake trout gurgle at the surface as they are expelling some of this air.

“However, these guys still experience barotrauma. Now it is important to note that there are a whole suite of other non-visible symptoms, including trapped gas in tissues and blood, crushed organs, internal bleeding etc…If you are fishing in deep water (~30 + ft), your fish are likely experiencing some degree of barotrauma which could drastically reduce their chance of survival.”

When barotrauma damage is present survivability of fish released drops significantly, and that is a concern in catch and release waters, or for fisherfolk choosing to practice C&R as a matter of course.

“Unfortunately, the chances of these fish swimming away and surviving is extremely low,” writes Eberts. “You’ve probably witnessed this in fish that just can’t seem to get back down, or remain belly up on the surface. This is because they cannot regulate their buoyancy, or they’ve experience too much trauma and stress as result of this barotrauma. Therefore, if you are looking to keep some fish for dinner, and you come across barotrauma fish, you might as well keep these ones as there is a good chance they won’t survive long after release. It’s important to remember that barotrauma, caused primarily by depth, is just one of the factors that can influence fish mortality, but it is one that we can reduce the influence of just by understanding how it works.”

So that brings us to the key question; what can we do to improve fish survivability in cases where barotrauma may have occurred?

Well there are some options for ‘relieving’ barotrauma, although Eberts suggests not all of which I think are appropriate for Saskatchewan fisheries.

“The most well-known technique is called venting or “fizzing.” This is the act of puncturing the swim bladder with a needle, in hopes of deflating this excess air,” she writes. “You may have seen folks doing this very thing at walleye tournaments in your area. Now if you are thinking to yourself, “this sounds intrusive”… you are correct. There are a number of problems with fizzing. Most obvious, venting causes a new wound to the fish, which could further become infected. This wound is primarily in the swim bladder; an organ that the fish needs in the future to regulate its buoyancy.

“Venting can also puncture other organs if not done “properly” or with sufficient training. Venting can be seen as an “out of sight out of mind” approach i.e., it allows you to sink your fish, but doesn’t ensure they survive. I was interested in how well venting worked and did a literature review of every study I could find that tested whether fizzing promoted survival. I found very conflicting results; In short, I found no evidence that this technique works for any of our Saskatchewan fish species. Through some unpublished reports I found that venting can actually be detrimental to walleye in particular. I do not advise venting your fish. But don’t worry – there are some other less invasive methods available.”

Eberts does offer what she says is a better option.

“Non-invasive methods of relieving barotrauma include descending devices and weighted cages,” she writes. “Descending devices work by sending your fish back down to capture depth, and in the process reversing the barotrauma they experienced on the way up. If you google “descending devices” you will see a variety of options and videos showing how these devices work. I’ve attached one of the “EcoLeeser” below. Although more literature is needed to see whether these devices work well for species in Saskatchewan, but it looks promising based on large amounts of literature on other fish. Weighted cages work in a similar way in that you send fish down in an inverted cage and then pull the cage up once you reach capture depth; at this point the barotrauma in the fish is relieved and they are able to swim away.

“Therefore, weighted cages work well for multiple fish, but might not be the best for large fish as you don’t want them to be cramped in the cage which could further injury. If you are interested in purchasing a descending device I suggest the Ecoleeser (www.ecoleeser.com), or something similar.”

It’s also an option to make a descending device.

“There are a variety of “do it yourself” descending devices online that you can replicate,” writes Eberts. “However, I went to a local fishing expert in the province, Jeff Matity, from Matity’s Get Fishing (www.matitysgetfishing.com), who introduced me to his creation, “The Survival Bomb”. With the survival bomb you gently set a barbless hook in the middle of the bottom “lip” of your barotrauma fish. NOTE: you are not hooking the fish, rather just anchoring it to attached weights. At this point your fish isn’t doing so hot, so this is easier than it sounds. You then descend your fish using the attached leader and rope, until capture depth. The best way to do this is pull out all the slack you need, chuck the buoy in the water, and let the fish descend on its own (if you hold on to the line you might accidentally release the fish too early). Once the fish is descended you give the line a quick tug and pull the hook free of the fish. If it didn’t work, you’ll see your fish rise again to the surface. The survival bomb works well because it has a buoy so you can let your fish sit at the bottom for a while, and keep track of them before you remove the hook. If you are interested in making a survival bomb make sure you use: a thick leader (whipper snipper line or 50 lb test) so you don’t get the fish wrapped up in the line, approximately one-ounce of weight per one-pound of fish,  and a snell knot on a barbless hook that has the line coming out at the bend of the hook not the eye (you want to pull the hook free, not set it!).”

Eberts does offer one other solid bit of advice in terms of subjecting our sport fish to barotrauma.

“What is the best way to deal with Barotrauma?” she asks. “The answer is to move in shallower! If you are fishing at 30 ft or more (I’d be cautious around 25 feet) there is a good chance your fish are experiencing barotrauma and aren’t surviving. Do the responsible thing and move in shallower so those fish live, and that fishery can persist. By no means am I suggesting that with a descending device you can fish deep water, barotrauma should be avoided at all costs. Do your best to avoid causing barotrauma, but be prepared to deal with it if you encounter it. If you are a tournament fisher, refuse to move in shallower, or are fishing a particularly deep lake, make sure you can at least facilitate catch and release! Carry a descending device!”

article continues below
© Copyright Yorkton This Week

Comments

NOTE: To post a comment you must have an account with at least one of the following services: Disqus, Facebook, Twitter, Google+ You may then login using your account credentials for that service. If you do not already have an account you may register a new profile with Disqus by first clicking the "Post as" button and then the link: "Don't have one? Register a new profile".

The Yorkton This Week welcomes your opinions and comments. We do not allow personal attacks, offensive language or unsubstantiated allegations. We reserve the right to edit comments for length, style, legality and taste and reproduce them in print, electronic or otherwise. For further information, please contact the editor or publisher, or see our Terms and Conditions.

comments powered by Disqus