Please put your measurements of open mouth width and total length of northern pike in this thread. Thanks for helping.

Bill, what's the best way to measure a pike's mouth width?

With steel gloves on that go up to the elbo securly attached by sholder straps. Keep your face and other appendages well away from the mouth as sudden lunges can cause extreme pain , disfigurment and phsycial detachment. --

First and formost the best way is to keep your fingers out of its mouth. It is almost a two man job if you do it on a live fresh fish. I would just slide a ruler across its mouth while the helper pulls the mouth open. I measure it on walleye often. Best and easiest way is to do it on a dead fish which is why I asked Cecil to help with this. He usually has pike in taxidermy studio.

I went looking and found a paper on northern pike gape size. I will email a copy to Bill Cody. Anyone else who wants to see it, send me an email. david.willis@sdstate.edu The authors measured gape of 49 northern pike of varying lengths (5-27 inches)in Sweden. The increasing cross-sectional diameter of a plastic cone (height 215 mm: base diameter 95 mm) was marked along its side at 2-mm increments. The cone was inserted into the mouth of the pike, and the diameter of the gape at the corner of the mouth was registered.

Pike gape size, as measured with the cone, was linearly related to total body length (Gape = (0.098 X total length) - 0.339, r2=0.987, P=0.001). In addition, the maximum prey size consumed at each pike length was quite a bit larger than what the gape size indicated would occur. They have a very nice figure that shows both gape size and maximum prey size as pike length increases. They used common bream Abramis brama L.) and roach (Rutilus rutilus L.) as their prey fishes for maximum size consumed; these are two European cyprinid (minnow) fishes.

The primary limitation is the relatively small size for the largest pike in the study (about 27 inches). Maybe Bill can add to it.

Nilsson, P.A., and C.Bronmark. 2000. Prey vulnerability to a gape-size limited predator: behavioural and morphological impacts on northern pike piscivory. Oikos 88: 539–546.

This is awesome. I wonder how my pike will measure up.

-Skinny

Bill,

39 inch pike has a 4 inch gape vertical and 3 1/2 inch horizontal.

25 inch pike 2 1/2 vertical gape and 2 inch horizontal.

As these are mounted fish one could possibly increase the gape on a live fish.

Dave how do you think pickerel would compare to that study?Any chance you think it may be close enough to get a guesstimate on their gape?

I have a 30"'walleye mounted that has a 3" wide by 2.5" high mouth gape.
Like Cecil said about the pike it is higher on a fish that is alive. I would guess 3-3.5" high.

Next catch we will measure a live one.

If the NP want the food bad enough they will grab it sideways and chomp down. This result in three nice bite size pieces; head, body and tail sections. They will probably leave the head and tail sections for someone else and proceed to another meal or go to the bottom of the weed line for a siesta. I have seen this while crappie fishing. They will chomp down on your crappie as you are winding it in.

I also know of at least one situation where a pike died choking on a spiny rayed fish. I was always under the impression they hit a prey fish and turned it around in their mouth.

RNJ -- I don't know. I would guess that chain pickerel would be similar to northern pike, but I don't know what minor differences they might have in gape width? Would a pike-like fish that has a smaller maximum size have a smaller gape at a given length than the northern pike? I don't know. I've only caught a couple of chain pickerel in my life, so haven't looked at many. I did a quick search on Google Scholar for chain pickerel and gape, and didn't get any useful papers returned. That does NOT mean there is no work out there, just that the quick search didn't easily turn up such work. So, my best guess is that chain pickerel and pike should at least be somewhat similar, but I'm unsure if there are minor differences between the two species.

to be clear, if i were to catch one of my dad's pike in the near future, we are looking to open the mouth as wide as possible, like with a spreader, measure "cheek to cheek" width, as well as height at the largest open space, and then total length of the fish, right?

Mind if I ask why we are collecting this data?

Having caught 100's of chain pickerel and a few dozen NP, my best guess is at the same size both species have almost the exact same mouth size. I can tell you from experience, chain pickerel rarely do well in ponds with a healthy LMB population though. Especially if that pond has limited SAV. The LMB do not allow their YOY to survive. I see chain pickerel doing best in ponds where the water is so acidic, LMB either can't live or do very poorly or in other habitat situations where LMB are at a disadvantage.

Ditto. I've also caught chain pickeral and mounted a couple for a taxidermist in Delaware and they seem to be identical as far as the buccal structure except smaller in overall body size.

cool study! hope I get to add some information soon!

Thanks Dave,for my pond that should be good enough to figure out what the few I have are capable of chomping on.

CJ, I wouldn't say they do well in my pond but they have been hanging in there for as long as I can remember.It's not rare that we catch one but it isn't often either.I have one shoreline with some reeds in the shallows and it seems they hang pretty exclusively in that region.I pull in a few every year while working the shoreline in this area at dusk and that is about it.

We are collecting this data about pike mouth size so we will have an idea of how big of prey fish that big pike could eat, be it a bass, perch bluegill crappie green sunfish, trout, walleye, etc.

My limited experience says there are seemingly inhumane ways to treat a NP that my uncle taught me to prevent harm. What keeps them from biting and thrashing is picking them up by the eye sockets. It paralyzes them for the duration, but they appear to recover just fine when released. Otherwise a small baseball bat should be employed to knock them silly, of which they do not always recover.

It sure beats loosing a finger.

We used to catch some large NP and Muskies on the St. Lawrence river, 30+ inches were not unheard of. I don't recall what mine was once, something like 26", and it put up an long fight to land it.

I always thought that pike could take chunks out of their prey, so is mouth gape that important? Granted it is likely much easier for them to swallow something whole than to take chunks out, but I remember frequently reeling in a larger bluegill or perch to find large portions missing. Those damned pike would hand out "in the holes" waiting for an incapacitated fish to eat.

I have a great love of pike -- northerns and muskies. To me, they are the ultimate fish.

From my pre-teen years through my early 20s, I caught thousands of them. I fished for them at least 300 days a year, and I caught a lot of them every time I fished. While in college I also guided for NP, musky, and walleye from Hayward, WI, through what is now the BWCA, to the Kenora area of Ontario/Manitoba.

I was probably about 10 years old when a neighbor taught all the neighborhood kids to make and use gaff hooks -- and he provided us with the cold-rolled 1/4-inch or 5/16inch rod, and his shop, to make our own. With just a little practice, he taught us to to grab a large gilled-fish from the water, unhooked from a lure, and quickly returned to the water without ever drawing blood .. the fish's or the catcher's. The gaff was used to grab a large fish behind the gill plate, and to quickly pull the fish straight out of the water. The front of the gaff would provide leverage and protection from the sharp teeth as a hook was being removed. The fish never touched the ground.

This same individual was probably a pioneer in catch and release in the 1950s, and in doing as little damage as possible to fish. He taught us to never touch the fish -- and especially to not use the popular technique of those days, to calm a pike by putting your fingers over their eyes, as you laid them on the ground to twist a treble hook out of their mouth, before throwing them back in the water.

Yes, they have a rows of sharp teeth. But, I've lost a lot more blood to catfish and bluegill that "speared" me.

Yeah, a gaffe hook would probably work great. It has been a VERY long time since I have caught a pike, fishing has been low on my list of priorities for years due to time limitations. Pesky jobs :-(

One thing I should note is that equipment and knowledge has changed considerably since my pike days. Welfare of the fish is now of utmost importance. Here is a really well written article on handling pike. http://muskyontario.com/releasingmusky.html.

The other thing I didn't think about when I posted above was use of a gaff, if you should choose to use one. Especially when watching salt water fishing shows, where a gaff is used, they impale the fish with the gaff. When I was still regularly pike fishing, our gaffs did not have sharp hooks. The end was rounded, and not at all sharp. They were also bent completely differently. Our goal was to get the fish close to the boat, or shore, and slide the gaff from the back of the gill plate so that the gaff hook came out of the mouth without injuring the gills.

Catmandoo- great link to good advice for handling and unhooking musky and large pike. Thanks for finding the info.