Ask the Biologist

**Craig Johnson** · 05-02-2011, 05:09 PM

Originally Posted by Lowellhturner

Sir, have a question; still awaiting the monsoon to relent to get back to adding more cover to CJ here in Ohio. Was told that crappie fry and juvenile fish don`t use cover at all, anytime of the year and neither do yellow perch. Obviously, am not an "expert' by any means, but am fairly certain perch spawn on cover, and have caught dozens thru the ice on/ very near cover, and have read very young perch are open water fish, is the same true for very young/ juvenile crappies? Realize seasons, forage and depth has a lot to do with it, fish won`t stay on cover if there`s no prey present...would think very young/ juvenile crappies would use cover. (Got $20 riding on this 1...)

Young of the year crappie are exclusively pelagic (open water related) as they follow plankton as it moves around the lake. These Age-0 (or young of the year) crappie don't relate to structure. Obviously, as the crappie increase in age they begin to use cover not only for protection from predators but also as ambush locations to obtain prey. It looks like your bet may hang heavily on the age of the crappie of which you are discussing. Good luck!

**Craig Johnson** · 05-02-2011, 05:18 PM

Originally Posted by springhillwantabe

craig the water temp has been 65* the crappie are in spawning the normal ks spring cold front gets here the temp drops to 55* what happens to that spawn?

Springhillwantabe,

Water is a beautiful thing in that it buffers the fish (and eggs) from quick variations in temperature. Air temps may drop dramatically in a matter of hours but water temperatures in a lake setting take much longer to change. This is good for eggs or young fry. Since the temperature change is slow, they can easily become acclimated and not suffer ill effects. Cooler water temperatures usually result in longer hatching times. If we were to have a huge cold front that dropped water temperatures to the point that plankton populations crashed, the fry would be in trouble as their food source would be non-existent.

I can read your question a couple of ways and I'm guessing that you asked about the fish that had already spawned prior to the cold front and not how the cold front affects fish that are still carrying eggs. Correct me if I'm wrong!

**springhillwantabe** · 05-02-2011, 05:34 PM

Originally Posted by Craig Johnson

Springhillwantabe,

Water is a beautiful thing in that it buffers the fish (and eggs) from quick variations in temperature. Air temps may drop dramatically in a matter of hours but water temperatures in a lake setting take much longer to change. This is good for eggs or young fry. Since the temperature change is slow, they can easily become acclimated and not suffer ill effects. Cooler water temperatures usually result in longer hatching times. If we were to have a huge cold front that dropped water temperatures to the point that plankton populations crashed, the fry would be in trouble as their food source would be non-existent.

I can read your question a couple of ways and I'm guessing that you asked about the fish that had already spawned prior to the cold front and not how the cold front affects fish that are still carrying eggs. Correct me if I'm wrong!

you hit the nail on the head thanks jim

**Lowellhturner** · 05-04-2011, 12:47 AM

Sir, collected the $20 as he stated "Crappie fry AND juvenile crappies neither use cover". Agreed crappie FRY didn`t, he assumed only "mature" (bigger) crappies use cover. To his credit, he read this and commented as he shelled out the money "Who`s this guy think he is, a biologist or something?" Forgive me but I couldn`t help to laugh and point out "YES, he IS a biologist; maybe that`s why the thread is called `Ask the Biologist`..." Good guy, but kinda leap before you look sometimes...I`m gonna buy bait ! Thank You...

**Flats&Craps** · 05-12-2011, 12:07 PM

Craig,

Are the feeders running at CSFL yet?

Thanks,
Cody

**Craig Johnson** · 05-16-2011, 11:02 AM

Originally Posted by Flats&Craps

Craig,

Are the feeders running at CSFL yet?

Thanks,
Cody

Cody,

Not yet. I hope to have the feeders up and running in the very near future.

**Lowellhturner** · 05-29-2011, 08:12 PM

Was speaking to a "Friend" recently, he bass fishes alot using various crayfish type lures and rigs (seldom if ever uses the real thing. he said was surprised at the # of smaller walleyes he catches on them. Understand walleye would probabily eat them, any idea how commonly this occurs? Also, assuming a crafish has clean water, how long will it take them to molt, assuming they have food continuously? How long untill they are "hard" again? Thank You!

**Craig Johnson** · 06-14-2011, 09:17 AM

Originally Posted by Flats&Craps

Craig,

Are the feeders running at CSFL yet?

Thanks,
Cody

Cody,

The feeders were up and running as of May 26.

**Craig Johnson** · 06-14-2011, 09:37 AM

Originally Posted by Lowellhturner

Was speaking to a "Friend" recently, he bass fishes alot using various crayfish type lures and rigs (seldom if ever uses the real thing. he said was surprised at the # of smaller walleyes he catches on them. Understand walleye would probabily eat them, any idea how commonly this occurs? Also, assuming a crafish has clean water, how long will it take them to molt, assuming they have food continuously? How long untill they are "hard" again? Thank You!

Walleye can prey upon crayfish and frequency would likely depend on crayfish density. Adult walleye feed primarily on fish although insects, primarily mayflies, do make up a large portion of the diet. Depending on the crayfish rig your friend is using, the walleye may be seeing this artificial bait as a minnow vs. the crayfish imitation it is supposed to represent.

Young crayfish may molt 6 to 10 times their first year and 3 to 5 times their second year. It will take a crayfish two to three days to regrow the hard exoskeleton after molting.

**Lowellhturner** · 10-30-2011, 01:48 PM

Another couple of questions: #1: the "Friends" will soon be back at it again and the subject of introducing rock rubble piles has come up repeatedly; I suggested simply await safe ice after deciding on a spot, mark and rope off a hole and use a chain saw to open the ice. Then simply wheel barrow the material to said hole and "Splash!" To expand said pile await the 1st hole to refreeze, break the chain saw back out and repeat as necessary. 3 basic differences of opinions as to how big they should be, how tall vs area and whether littering them with 3 and 10 hole red bricks would further "enhance" the ensueing crayfish populations. My guess was 10` round, 2` tall and HECK YES! Placed on a flat gravel/ sand area creating these transition zones alone would be a fish magnet, plus the crayfish habitat? #2: Several persons want to create cat spawning areas. I suggested 12" cement or steel culvert pipe 3`- 4` long. They laughed, saying a cat wouldn`t use it. #3: There is quite a bit of talk about attempting to introduce SOME kind of aquatic plants to several shallow bays and inlets bordered by DEEP water. Keep in mind the reservoir gets drawn down 3-5` every winter. Can you think of any plants that are freeze resistant yet not very prolific that might work. I REALIZE that many plants ARE extremely "prolific" and can quickly become a problem. Your expert opinions, sir and again, Thank You !

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