Saturday, April 22, 2006

never try to eat anything bigger than your head

That's the moral of a story I'll be getting to here shortly. I've been really busy with work, and I even worked this morning, a Saturday, which is rare for me. We're doing our every-five-year muskellunge (Esox masquinongy) assessment on a lake south of here. We stock the little muskies in the lake when they are about twelve inches long, and the assessment is to see if some of them are growing into big muskies.

To capture muskies live, we use trap nets, which are a series of hoops into which a fish swims and cannot swim back out. The hoops are connected to a fifty foot long panel of mesh that is set perpendicular to the shore. A fish swimming along shore will encounter the panel, try to swim around it, and be led into the trap net. If all goes well, it works nicely.

Today was a pleasant day to be out on the lake, with partly cloudy skies and very light wind. It was one of those days that make me think, if I have to work for a living, there are very few things I would rather be doing. I just like being out in a boat, in the water. While checking the nets we saw buffleheads, mallards, and wood ducks, a small flock of white pelicans, an osprey carrying a fish in its talons, a large raft of coots floating in the exact same spot they've been for three days now, great blue herons, Canada geese, and one swan. Sorry no pictures; I thought about bringing the camera but also had the vision of my camera ending up at the bottom of the lake. Best not to take chances.

We had a total of eleven muskies in 15 nets, which is actually a good catch rate. Most of them were around forty inches, which at over ten pounds are pretty nice fish, but I also saw and handled, for the first time, a 50-inch muskie that weighed 34 pounds. Wow. What a fighter. I finally realized what it is about this species that makes some anglers almost obsessed with them; they are the barracuda, the shark, the wild alligator of Minnesota lakes. I decided, awesome as they are, I would rather not tangle with one that had a lure with three treble hooks embedded in its mouth, at the end of my line. I don't go looking for trouble.

We also saw some nice sized, 11-12 inch black crappies (Pomoxis nigromaculatus), 19-inch largemouth bass (Micropterus salmoides, or Hawg!), walleye (Stizostedion vitreum vitreum, which has since been changed but that's how I learned it!) and northern pike (Esox lucius). Which brings me to the title story. Today I saw a northern pike that died of gluttony. This fish, 23 inches long and maybe three or four pounds, with an elongated fusiform shape (think cylinder), had tried to ingest a black crappie that was perhaps too much for it. The crappie, which we pulled, half-digested, from the pike's upper throat, was perhaps nine inches long, maybe a quarter pound, but from dorsal to ventral a crappie that size is a good three or four inches high, a good inch or so bigger than the diameter of the northern pike. Furthermore, a crappie has spines in its dorsal and anal fins that point backwards, preventing a predator from changing its mind and regurgitating the crappie. The northern pike was still barely alive when we pulled it from the net, crappie tail hanging out of its mouth, but with such a large, non-cylindrical fish lodged in its throat it could not effectively ingest water to pump through its gills. Even after removing the crappie, we could see that this pike had attempted its last meal.

Fish never fail to amaze me. I guess even wild creatures have their unfortunate moments.


doubleknot said...

Nice fish tale. It is nice to be working at a job you like.
That pike had eyes bigger then it's tummy just like people do sometimes with things.

Floridacracker said...

You used the word fusiform! God bless you.

I force my marine science students to learn fish forms and they stress over knowing fusiform, compressed, depressed, and attenuated...
Nice to hear a real fish biologist use it...reassures me that I'm not teaching gibberish.

...well, sometimes I do :)

Laura said...

Recollections of my creel census days are a little blurry now, but I'm thinking I remember, from the brief time when we took stomach samples from the fish we were cleaning - there was one fish stomach that contained a fish eating a fish.

Deb said...

doubleknot- yeah, I just could not handle a full time office job. This is fun!

FC- Believe it or not, I had a dream the other night where I was fighting with someone, one of my supervisors actually, about the identification of minnows; he thought they were golden shiners and I said "No! They're fatheads! They are definitely not dorsoventrally flattened!!!" :)

I don't think I had used the word "fusiform" since grad school ichtyology days.

Laura- the food chain, in action! I don't make my creel clerks take stomach samples though. ;) I was cleaning the northern today, giving the kids a lesson in fish anatomy, and I found crappie scales in its throat.

By the way, I think I may be allergic to esocid slime. The backs of my hands broke out after I filleted the northern.

pablo said...

I'd bet there are plenty of fishy tales like these that simply never make into the research nets of lovely biologists. By human standards, I'd bet the critter world is one constant horror.

Rob said...

That reminds me of this footage I saw once of a large catfish that had tried to eat a soccer ball. It was stuck near the surface thanks to the ball's buoyancy and was unable to let go of it, it had become so stuck in its mouth. It took a guy knifing the ball to rescue it!