Lake Michigan Perch Gut Analysis

[unirdna]

Curious what they eat to get so big - what's in those fat bellies? Me, too. Let's take a look... I opened every stomach. Here are two fish that still had undigested food.

13.5" fish:

Notice the accumulation of fat (white stuff surrounding the stomach). These guys are eating very well.

Separation of stomach and fat from other viscera.

Contents of stomach: 2 Alewife and 3-4 unidentifiable, small skeletons

And a 12.5" fish. Not as much fat on this guy.

One Alewife and one Goby:

There you have it. I find it of particular interest that the perch are growing large on INVASIVE species. I'm not drawing ANY conclusions from this data, just saying that it is good to know that the native fish have a taste for the new-comers.

Ted

 

[Whopperhead]

I opened the stomach on the 14" and only found 2 Alewife's and some unidentifiable matter. There was also LOTS of FAT!! Sorry, no cool pics like unirdna's.

Good post Ted!

 

[unirdna]

Oh yeah... I'm taking scales from the 13.5 fish with me to work. Age analysis coming soon...

 

[bgill]

I found crayfish and 4-5 inch alwife in mine...Usually just crayfish though!

Cool pics... I'm curious to know how old a 13.5 incher is!

Let us know!

 

[unirdna]

I found crayfish

How many crayfish? Please post a photo (next time). Perch are not known to be big crayfish eaters. I've pumped the stomachs of countless perch on inland lakes, and never once found a crayfish. Becker (Fishes of Wisconsin p. 890), states that in L. Michigan, near Milwaukee, 98% of the volume of YP diets consists of alewives and slimy sculpin (pre-goby research). If you find them eating crayfish, that could definitely be a point of interest for fisheries biologists.

Ted

 

[bgill]

Usually just one or two...Even the Lake Geneva perch I got the other day had a crayfish in it...

The Lake Michigan perch from yesterday also had alewife tails STICKING OUT of thier mouths! They were stuffed...LITERALLY!

Next time I'll post some pics for ya...FYI - It seems to me that when I find crayfish in perch they are USUALLY "soft shelled" crayfish...Or "molted" ones. Probably a target of opportunity when huntin' gobie's.

 

[unirdna]

It seems to me that when I find crayfish in perch they are USUALLY "soft shelled" crayfish...Or "molted" ones. Probably a target of opportunity when huntin' gobie's.

Ahh. Good observation! Panfish do the same thing when they are kept with crayfish in an aquarium. The can "smell" the molting.

 

[dotey]

I also found a cray fish in mine as i was cutting it up one poped out of his mouth i also talked with a buddie of mine and he uses cray fish to catch them line and pole

 

[unirdna]

Cool. Thanks, Dusten.

13.5 inch perch is about 8 years old. By comparison, eight year old perch in Mendota average just a little over 11 inches.

 

[Kyle in WI]

Nice work. Thanks for taking the time to document and share this with us. I'm glad this forum has someone so knowledgeable, I'm sure you get alot of fish and water questions. I'm sure I'll have a few for you.

 

[bglaeser]

I'vr seen perch actually eating crayfish.... they were going nuts... it reminded me of a minature shark "feeding frenzy".

Here's an idea.... someone needs to find a good place to spear perch in Door County.... GREEN BAY side....... the limit is 15 perch/day there. A 3 day weekend would net 45 perch.
~brian

 

[unirdna]

Three of today's perch had stomachs full of food - a 14.25" 13.75" and 13.50".

Both 13.x" fish had two alewives each.

The 14.25" had these little fellas in his crap factory.

 

[bgill]

See...Told ya the bigger ones got "craws" in 'em!

 

[Whopperhead]

Pretty much Alewife's in all my Perch. Oh and a License plate in the 14.5" Perch.

 

[fleshy]

Lots of interesting/cool information on this post! Not surprised about the alewives, however the gobies and crayfish came as a surprise! The way the perch's mouth is built, and the "altitude" at which I see them swimming in the wild would suggest prey such as alewives, (fish that are swimming "midwater"). Could the softening of the crayfish shells merely be from digestive fluids? Most invertebrates are pretty good at hiding while their hide toughens. Cant fight hard core evidence though. It would be awesome to do similar research with other fish!

 

[unirdna]

Altitude, under water, is called depth . But, joking aside, yes, the crayfish were softened by digestive enzymes. The carapace may not have been as hard as normal, but it definitely wasn't newly molted. The aren't just taking the "dumb ones", they are actively hunting. I was surpised, as well. Perch are not well known as "bug eaters" (like smallies).

 

[fleshy]

Depth... ha ha. Well we all have our moments. When shooting carp in Egg Harbor Ive fed smallies small pieces of carp guts that get ripped out with the spear. Now they follow me around. Ill be on the bottom, and Ill turn around and there will be about ten of them just sitting there. Another time I found a rapala bait and decided to see if it works by gently pulling it in front of them. They were interested, but I think my size/motion intimidates them.

 

[the_duckinator]

I've caught panfish and small bass while snorkeling by jigging a small twister tail on a 6ft piece of line. It's great fun

 

[Trident]

Wow! This thread is awesome! I too have never thought about opening her up

I was always to afraid to "see that thing cut open and have that little Kidner Boy spill out all over the dock." (attempt at Jaws humor) :duh

Thanks for the findings ya know what they say... NO Guts - NO Glory ! (I just can't stop) :t