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Location: Green Bay, WI | Muskies are Physostomes, and have a duct that connects their swim bladder to the gut. Perch and Walleye are Physoclists, and have lost the duct in development; these species have a special vascular structure called a rete mirabile for gas exchange to/from the swim bladder. Although we generally think of a fish species as being either Physostomous or Physoclistous, I've read that there are actually some fish species with both--a duct that connects the swim bladder to the gut, as well as a rete mirabile. It may not be as significant as in a pure Physoclist, but it's apparently there nonetheless. However I have not been able to find a reference that mentions any such species by name, and I am wondering whether or not muskies have any rete mirabile at all? Does anyone know?
I asked Sean Landsman, but he doesn't know for sure--so I'd thought I'd post it here in hopes that someone might know. I'm looking for any reference that someone might know of that discusses this. I am also looking for a good reference text on the basic anatomy and physiology of fresh water fishes. I have Becker's Fishes of Wisconsin, and that has a few things--but that's not really a reference on Anatomy or Physiology. So if anyone knows of a good reference on this, I'd appreciate it!
TB
Edited by tcbetka 4/18/2011 8:55 AM
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Posts: 1906
Location: Oconto Falls, WI | Interesting, but I question why you want to know this?  |
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Posts: 1937
Location: Black Creek, WI | If their gut connects to the swim bladder... it may explain the BST that muskies porpoise to "gulp air" after spending time in the depths (deflated air bladder).
Just a thought....  |
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Posts: 1906
Location: Oconto Falls, WI | That makes sense J, but how would you explain why muskies that are in shallow water (less than 5') porpoise as they shouldn't suffer from this same problem? |
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Location: Green Bay, WI | CiscoKid - 4/21/2011 11:45 AM
Interesting, but I question why you want to know this? :o
I have my reasons...
For one thing, let's just say that I am very interested in the depth structures (extremes) one could expect to encounter a theoretical musky of giant proportions in very large bodies of water.
But basically, it's just that I've heard various hypotheses over the years and am trying to follow up on some of these ideas. I'm trying to learn as much as possible about the species as well. The other thing is that someone should know these types of things, don't you think? Someone should know the answers to such questions. If no one else seems to know, then I guess I've volunteered to try and find out..
TB
EDIT: I just ordered a fish physiology text book that Sean Landsman recommended. Basic shipping was included in the price of the book, so I splurged and kicked in a whole $3.99 extra to get it delivered overnight. Amazon.com ROCKS!!
Here's a link to a preview of the book I ordered, for those who might be interested in some fish physiology:
http://tinyurl.com/42hxrcc
Edited by tcbetka 4/23/2011 8:14 AM
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Location: Green Bay, WI | CiscoKid - 4/22/2011 1:07 PM
That makes sense J, but how would you explain why muskies that are in shallow water (less than 5') porpoise as they shouldn't suffer from this same problem? ;-)
For Travis, or anyone who knows...
I've never personally witnessed a musky swimming with its mouth open and out of the water. I have seen a video of it on YouTube as I recall, but I don't recall if they noted the time of the year it occurred. But here is what I am thinking...
One possible explanation I can think of for this behavior, is air surface respiration (ASR). This is a behavior where the fish positions its mouth as near as possible to the water surface, in order to take advantage of the increased oxygen content in the first few millimeters of the surface layer. So they may not actually be "gulping air" mind you, but simply respiring this oxygen-rich water over their gill membranes to increase their blood oxygen level (pO2). Certainly they may be gulping air into their gut, and then into the swim bladder. But according to the reference I linked to above which I just received , on page 104:
"ASR has been documented for many species, its extent of use correlating directly with the severity of aquatic hypoxia. Morphological specializations for ASR include a terminal mouth, a flat rostrum or dorsal body surface, and the capacity to increase buoyancy (either using the gas bladder or air gulping) to optimize mouth position."
The text goes on to report this behavior in species such as this:
http://www.seriouslyfish.com/profile.php?genus=Ctenolucius&species=...
...so it seems reasonable that northern pike and muskellunge may be engaging in this activity as well. It may also explain why the fish don't seem to be in the mood to eat, from what I've read from guys who've seen fish do this but couldn't get them to hit a lure. If the fish are trying to oxygenate their blood, then why would they want to eat? No matter how hungry you are, I think most animals would prefer not to sacrifice breathing for eating. I suppose the behavior could also be a combination of air-gulping to increase buoyancy, and ASR to increase pO2 in the blood.
So I guess my questions for you guys who've seen this behavior, are:
1) What time of the year do you typically see fish doing this?
2) What are the approximate water temperatures when this occurs, if you recall?
3) Does there seem to be any correlation between wind speed (i.e.; lack of waves, or calmness of the water) and this behavior?
4) Have you ever seen it over deep water, or is it confined to relatively shallow (and hence, likely warmer) water?
5) If you've witnessed the entire event, for how long did it last? Was it a number of seconds (15-20+, for instance), with the fish swimming in a level attitude; or was it a momentary event, lasting only a few seconds?
I think you can probably see where I'm going with these questions. If the behavior tends to be observed mostly the summer or early fall months (when the water tends to be highest) and also when it's more calm, then it certainly may be that the fish are trying to take advantage of ASR. As these warmer water levels would have lower DO levels and the lack of wave action would contribute to decreased oxygenation of the water, it may be quite understandable that the behavior would be seen more frequently under these conditions. However if the fish are doing it over deep or shallow water; equally in cool/cold or warmer water temperatures alike; and with any sort of wave action...then they could in fact just be gulping air for their gas bladder.
EDIT: Here's a couple videos of such behavior...
http://www.youtube.com/watch?v=TO7u77qio0I&feature=related
http://www.youtube.com/watch?v=kGQCF7TBiKI
TB
Edited by tcbetka 4/23/2011 7:54 PM
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Posts: 16632
Location: The desert | Tom,
Interesting theory you propose. It may very well be ASR, but I have my doubts. I've seen tiger musky do this on calm days, in the summer which would support your theory. I guess I would wonder why they would be in hypoxia? What is using up all the dissolved oxygen and why do they only need to do it a time or two then can go on breathing in the same water for the rest of the day?
I've seen suckers attempting this and/or gulping for air in a small reservoir that was sedimented in by a flash flood over a recent wildfire area. They found what little water was left and were angled up to the surface trying to get every bit of oxygen left. Whether it was ASR or gulping or if they were just purely out of water and this was the only place to go, I don't know but ASR would give some insight into why they were all doing it the same way. But a tiger musky will do it, then swim off and not be seen again. If they were in dire straights oxygen wise wouldn't this need to be a continual thing until the wind blows again and stirs in some more O2?
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Posts: 1937
Location: Black Creek, WI | The Air bladder is for balance and bouyancy control... correct? It has nothing to do with "breathing". Thus, DO levels should have no correlation to the porpoising activity.
But... I'm just an barstool biologist so don't read too far into the BS.
Since most "porpoisers" are tough to catch... my ego likes the theory that they are done feeding deep and now on the rise to digest their meal in warmer waters (gulping air to inflate the air bladder). Thus why they ignore my offerings (not hungry anymore).
Often when I see a porpoiser, they leave a bubble trail as they dive back down. This tells me they either were feeding (slurped something off/near the surface) and the intake of air was coincidental.... or.... they were gulping down air on purpose.
Interesting discuss....
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Posts: 535
| I often wonder all of this myself, I have seen muskies do it in shallow water and over deep water, I have seen muskies do it calm and windy out, overcast and sunny, I see them do it all summer long and into the fall, maybe I dont see them in the spring because season isnt open yet so I'm not out yet. Also I have noticed that usually a hour before they do the porpose thing they are more active to chase baits, so when I see this I take note of it and head out to that lake a hour or two before I seen them doing the next day. I have never seen northern pike do this before though and wondered about it. Also another question is obviusly this behavior is not needed because how could they do it when winter rolls around and there is ice? |
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Posts: 535
| I think that DO levels dont have anything to do with it. I think maybe it is mostly to control there bouyancy, and to quicken the digestion maybe. |
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Posts: 2024
| I'm a firm believer that this behavior is a direct result of the fish attempting to regain buoyancy through their pneumatic ducts and air bladders. Changes in barometric pressure, which translates to changes in hydrostatic (water) pressure, have an impact on pressure within the air bladder. A drop in pressure allows expansion of the air bladder, which theoretically could cause the fish to rise closer to the surface and be more susceptible to angling (see the newest issue of In-Fisherman's "Pike and Muskie" mag). Perhaps the behavior of fish at the surface is their attempt to expel air to achieve greater depths or to gulp air to release pressure.
It would be an interesting experiment to assess behavioral changes in a laboratory setting under differing barometric/hydrostatic pressures. |
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Posts: 1906
Location: Oconto Falls, WI | Porpoisers are what I feel, like Long, fish that just ate. They do it at all times of day regardless of conditions. They even do it at night (seen on full moon nights).
The head out of teh water deal is a strange one, and I have also seen it year round and throughout the day. Varying conditions from calm to a breeze. Never seen it in a heavy wind though. One thing about the ehad out of teh water fish is I have never seen a true musky do it. It has always been tigers, and pike. They also get more than just their gills out of the water! One very large tiger I saw a few years back was a good 2' out of the ater straight up! Stayed out for what seemed like 1-2 minutes! In fact I was mid retrieve and the blasted fish ended up swimming right into my line, and just kept going. I had to be careful not to snag it (as tempting as it was with the fish). This fish was out over open water. |
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Posts: 5
| I've seen 2 types of surfacing activity (other than fish that are chasing or eating something.)
1.The REALLY weird type is when fish swim around at approx a 45 degree angle with their head sticking out of the water. They move along at a steady, medium pace. I've seen them go a couple hundred yards before going back down. They get so high that their entire gillplate/ gills are above water line. I've gotten close enough to cast to them, without result. I've also gotten close enough to them that you could tell they noticed us and turned away. The fish I've seen were true muskies(not tigers), mostly on stocked MN lakes, and the lake where I've seen it the most has both Leech lake and Shoepac strains. I don't see this real often and it doesn't seem to have a certain weather pattern.
2.What I refer to as "porpoising" is different. I see this ALL THE TIME. The fish come to the surface very briefly, then go right back down(usually almost straight down). I can't say for sure that they are actually swallowing the air, but they definitely are gulping air and they leave a bubble trail as they descend. My feeling is they are gulping air into the swim bladder. My experience has been that this occurs FAR more on hot, calm summer days, mostly in late afternoon-early evening. It seems to be more common when water temps are fairly high too, which would tend to make you consider the disolved oxygen/breathing theories, but as I said, they are definitely GULPING and not staying near the surface for more than a split second, so it seems like a swim bladder thing to me. We'll often see multiple fish in relatively small areas porpoising within a fairly short timeframe.
Most of the time fishing has been pretty slow before and during the period when the muskies are porpoising, but we've had very good success going back to them a short time later, after a change in conditions. They seem to be fairly inactive (or at least not aggressively feeding) fish that are starting to become aggitated and more aggressive.
Oddly, I also have a lot of fish that will do this exact behavior a few yards behind the boat about 30 seconds after follwing a lure to the boat. |
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Location: Green Bay, WI | Right...we are talking about two different behaviors here: One where the fish swims at the surface for a prolonged length of time (seconds to even a minute), and one where the fish comes out of the water (or partially so) for only a second or two. In the former, the theory of ASR seems to be a plausible explanation, but that wouldn't really explain the porpoise activity that might last only a couple of seconds. That would seem to be more consistent with them taking a gulp of air to replenish their air bladder. Either that, or they are just doing it for the same reason a dog licks itself...
TB |
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