Ever see a kid spit milk out his nose? Most mammals are plumbed about the same way. It's not too hard to imagine how a semi-aquatic mammal could have learned to exploit that pathway to get scent-bearing water across the proper receptors. A closed glottis and a bit of tongue work would be sufficient to pump water back and forth. Mink generally hunt in streams, so detection means food is upstream - it doesn't have to be a particularly elaborate system to be effective.

The study I referenced earlier demonstrated moles and water shrews tracking prey by blowing bubbles, which remain attaches to the nostrils, and "vacuuming up" scent to track prey underwater.

Seals can track fish by detecting their wake with vibrissae. Dead fish don't leave much of a wake, but it's yet another example of a mammal doing something that we have a difficult time imagining.

EDIT: Latrapper responded while I was typing, and he's exactly correct about taste and smell being far from distinct senses. Underwater olfaction has been well-demonstrated in snakes, fish, and even plesiosaurus. "Tasting" water has been demonstrated in turtles and lizards. Both (or neither) may be at play here.

I don't think some of these things are all that hard to believe, like taste, or feeling vibrations, even humans with our weak hearing compared to most animals can hear when under water. I just don't think smell is one of the special things when mammals are underwater. To smell something you must breath in and the last time I checked mammals don't breath on their own under water which is why drowning rigs work. I would sooner believe that sight was a bigger part in this (perhaps from shore is saw a quick flash of a minnow swimming and dove in then as it would turn out found a dead fish.

Goes to show that there is a lot of what animals do where we don't understand the "how" very well.I doubt if there is much grant money available for the study of "Aquatic Mustela Olfactory Capabilities While Submerged and Foraging" though.

Back to the original question.I still think that mink used it's eyes to find that fish. Being a clear water situation I'm going to assume that visual acquisition would be the most effective "but not it's only" way of locating prey. We all know that mink certainly don't stop hunting in low light and other situations where vision may not be the most efficient method.

To broaden this out a bit. Might also the vibrissae of mink be used in a similar fashion to that of seals? Allowing more efficient foraging when vision alone would be inadequate.How about some combination of Vision,Smell/taste,Hearing/feeling?

I have always thought that animals would use ALL their senses relying on the ones that provide the best information available for the situations present.Even if we can't definitively say how they are doing it it is interesting to think about.

CC in order to drown they would have to breath under water or at least aspirate water into their lungs. If not asphyxiation would be the cause of death

Ric point well taken, I should have rephrased that more like in oreder to smell you must breath in air and the scent particles, mink do not have the ability to serarate scent from water nor do them have the ability to separtate air from water which is why drowning sets work.

Go back and read Dusty and my post. Just because you don't understand how it would be done doesn't mean they can't.

I don't be this to be a red herring, but I say the mink didn't know there was a fish in there. I think the mink found one there before and just decided to try its luck again. If the mink gets close enough, it can find its prey by feel.

Hal

Underwater olfaction should be an easily-funded graduate project - if you can develop a defensible method to test it and find the right advisor. (And mink are back to being Neovison vison.)

Seals have something like 7 times more innervation in their vibrisae than cats. Judging by foramina, mink are closer to the cat end. They probably can't do much more feel for movement behind a rock with them.

Of course they use everything they have anytime they can, just like the rest of us. I'm mostly just hoping someone has caught a blind fat mink or something.

CoonCaller - the paper I've cited a couple times was in Nature a couple years back. (Nature is pretty much the Holy Grail of biological publication.) You should publish a rebuttal.

I'm not saying animals can't do amazing and sometimes hard to believe things, I just don't think mink are smelling things underwater.

As far as the smelling things goes, I know beavers and otters both have a valve in their nose that closes when they submerge. Do mink have this same valve? And if so, would that not prevent them from "smelling" anything underwater? I suppose it could close far enough back that it would prevent water from entering the wind pipe but still allow it to circulate between the mouth and nose. This would make a very interesting graduate project. I'll keep it in mind for a few years hence.

Let me describe this fishing hole a little better, and answer a few questions, so we're all back on the same page. As far as the mink visually seeing the fish, through 100 feet of water, that's impossible. And, I can't buy the theory about it following the "flash" of a minnow, another 90+ feet, and it just got lucky.

You guys keep calling it a pool, this "pool" is 3-4, maybe 5 acres in size? Let me put that into perspective, this water hole has an area of 3 football fields, give or take. I was fishing The South Branch of the Potomac River. 50 yards upstream from where I was standing the river "pencils-down" to 50-75 feet wide, it gradually spreads out with a little "slack water" on both sides. Beyond the slack water, it's just a slow & lazy water hole, for the next 200 yards or so. There is a main channel that snakes down through the hole, but basically once you get out 10 feet from either bank, the water will vary from 4 feet deep, on up to 6 feet, and it's fairly consistent until you get to the lower end of the hole.

Like I said, I know this hole pretty good. I've trapped it from the east and west side. Dad, my brother and I have gigged eels and suckers from the boat in this hole, dozens of times. The 3 of us used to snorkel a good bit looking for treasure (mostly junk) folks lost while boating/canoeing. I've been out snorkeling alone and found more junk than I could carry. From knives, pliers, poles, tackle boxes, to lanterns. You name it, chances are it's in the creek someplace. In my experience, finding a dead fish on the bottom isn't unusual. At the same time, I wouldn't be surprised if 10 guys searched 3 acres of river bottom for an hour and did not find a single dead fish. We've got turtles, too.

That's the only mink I've ever watched swim, out in the open water. I'll tell you, it didn't make much of a ripple, they ride pretty deep in the water. I'm not sure if a mink can see much of the bottom while it's swimming (on the surface) or not? Over the years I've watched my dogs swim into rocks and logs that were only a couple of inches under the surface. My opinion, even if the visibility in the water would have been 10 feet, the odds of a mink (or diver) swimming 100 feet and finding a dead fish (visually) are slim. The mink dived off the "bucket rock", dog-paddled roughly 100 feet, went under and resurfaced with a dead fish. . . just like clockwork. It didn't dive and resurface, again and again and again. As well as I could tell it swam in a fairly straight line from point A to point B.

Above we talked a little about search/rescue dogs. I hate to talk about negative stuff and I hope no one gets offended by this, but a while back 2 men drowned in the same river. To make a long story short, the 2 guys went night fishing, and when the sun came up their boat was found anchored in 10-12 feet of water, with no one on board. Their fishing poles, PFD's, etc. were all in the boat. We'd had some hard rain storms, the river was up, swift and muddy. My brother is a member of the "dive team" for the local volunteer fire dept. Basically they were feeling their way around the bottom of the creek, kind of dangerous when your visibility is measured in inches, Bud told me it sucked!

Anyway, they brought in some kind of search/rescue, cadaver dog, called the divers out of the water, put it (the dog) in the front of a boat and motored over the search area. I didn't see the dog working, my brother told me about it, as did several of the police/firemen. At first I thought there's no way a dog could sniff-out a person's body underwater, especially in those conditions. Apparently the dogs handler thought his K-9 was up to the task. If a K-9 can sniff out a body in 10+ feet of swift/muddy water, I have no problem believing that it's (at least) possible a mink could sniff-out a dead fish under 5-6 feet of relatively calm water.

Dogs can be trained to do amazing things. Think about this for a second, how many hours of "underwater recovery" training do you suppose the dog and it's handler undergo per year? How many hours of similar "training" do you suppose a wild mink averages per year?

Here's my theory, I think the mink caught scent of something edible while on the river bank, and followed the scent trail very close to the fish, using it's nose in a normal manner. I'll agree, once it dived underwater or was within 6 feet of the fish, it's eyes took over the search. My opinion, I think it "found" the fish with it's nose first. Can anyone agree/disagree that my theory is possible? Maybe the mink was just lucky?

As far as the mink "smelling/tasting" while submerged?, you're over my head with that question. ???