Pond Boss Forums GENERAL QUESTIONS Water chemistry Anderson Split Pea Soup

I m with Augie, I dont think theres any way to keep them out of your pond. it all depends on what you do with them when they arrive. With the introduction of CC in QAs pond I think he will see a drastic drop in their numbers.
I got some of the craws from QA only to discover there were already a ton of them in my new pond. every one the young CC I caught were full of crawfish, they love them and I suppose can catch them pretty easily, I opened the stomachs of the CC to see what they were consuming and pretty much 100% of them had crawfish present.
That being said, It seems like I read somewhere on a thread on this sight that they are inferior quality of a food source, I dont know about that but my CC are doing extremely well, also in an older strip pit that I fished in a lot we would catch huge bass, we never did check any of the large bass but any bass we culled had craws in them and a Strike King rubber craw was their favorite lure, I still fish a lot with them to this day. but that was before the otters cleaned that pit out. they are slowly coming back and we are being able to catch a few again.

I don't have sufficient habitat for crawdads. The only shallow areas I have are the boat launch and a failed brook trout breeding area. Otherwise, step off the bank and its straight down. Sure, it's possible they are in there and bigfoot is feeding on them at night, but I highly doubt it. Sasquatch are vegetarians.

There is a reason every state in the US regulates crawdads, native or non-native, as do most industrialized countries in the world.

"Sasquatch are vegetarians."

I've often wondered about that.

Gehajake, I used to think that because I read it here. But subsequently a chain of events changed my mind. Ewest introduced me an article on Pike in Arizona where there is a rogue population of Northern Crayfish that has been introduced. In the lake with the highest growth, the pike preyed predominately on crayfish in the spring and carp in the summer. They listed the wet weight energy content of multiple species as measured by various authors. Both Northern Crayfish (the kind QA has) and Carp are significantly more energy dense than Centrarchids. Because these values were determined by standard experiments, I elected to change my mind and accept as true that Northern Crayfish are better quality food than BG and allowed the unanswered question that WRC or RSC may also be too. Below is the table of wet weight energy densities:




Although this evidence is anecdotal, it is evidence that crayfish presence does not prevent your CC from exceeding expectations or LMB in that strip pit from becoming huge. They appear to be very good forage for both CC and LMB as your experience exemplifies

According to that chart the Northern Crayfish should be an excellent food source for predator fish, thanks for the info, I do know that several local BOW that I fish in in this area have a lot of crayfish and the predator fish really love them, and for the most part, with a stomach full of digesting crayfish remains, they seem extremely healthy looking and vigorous, I have never weighed and measured any to establish a relative weight percentage, I didn't realize there was such a thing at the time. I am watching that in my new pond, and am for the most part at 100% plus, and I'm thinking they are getting lots of craws. the pond is built in and old sandy creek bed with an even bigger creek going across behind, parallel to the dam.

Crayfish perform housekeeping duties the benefit of which I think contribute in ways beyond their role as prey. Their activity helps to recycle nutrients and maintain a healthy pond bottom. This activity has the potential of increasing the production of other prey organisms. IOWs having a well balance crayfish population could make more prey of other species available too. This effect has also been noted of TP which perform similar duties but crayfish can perform these tasks and reach high standing weights when pond temps are cool before these other species really get active.

To be sure, too many can cause unwanted side effects like water that is too turbid but I think in a good balance this turbidity would show up in mid to late spring when numbers are peaked and then diminish significantly the remainder of the year. I am planning for them in my pond when that happens and I will also likely culture them as well. They are important in your water or they wouldn't be so prevalently consumed.

Jpsdad - I also much appreciate your posts. My water is very eutrophic even though it has never seen a single pellet of feed. I have chara coming out of my you know what. The phosphorus content of my water is high coming right out of the ground so nutrient removal is going to be something I deal with forever. I am becoming very interested in the topic. Once I achieve reproduction , my initial target was to remove 200lbs of fish per year starting in year #3 after reproduction and then evaluate/adjust from there. I should be able to add some pounds of crayfish on top of that. After reading some of your posts it sounds like that might not be enough to make a dent in the phosphorus load.

I learn something new everyday! I had no idea crayfish were so high on an energy density list. I have to imagine that fatheads, another component in my lake, are rather low in energy density. This gets me excited to see what kind of growth my Brook Trout will see off of these guys!! Doesn't take too many this size to make one pound of crayfish.

Nice touch there wbjr,
I love the double meaning of the slogan on that choice of beer can to put in the picture. Born in the rockies also applies nicely to those giant crayfish too!
You sure your trout can eat crayfish that large?

Those are langostinos!!!

A lake in Northern Wisconsin that I fish (and shall be left nameless because the WI DNR says that there are no SMB in there) had Rusty Crayfish introduced to it somehow. They pretty much completely denuded the lake - very few submerged aquatic weeds in there now. At night if you take a flashlight and shine it on the bottom of the lake there is a crayfish walking around for every square foot of pond bottom, maybe more.

Smallmouth look like pellet hogs. Last one I kept from there was 19" long, 19" around and weighed 6#.

I'm trying to figure out if the Colorado Koolaid can is 16 oz or 12 oz. Not for sure if my memory is correct but didn't Coors once sell a 14 oz can?

Anyways, the crayfish are large. It will interest you to know that the dry matter of all living things LESS the mineral content has a very close relationship to energy content ... at least for those organisms that have be tested thus far . Most of the minerals are calcium and phosphorus with other minerals in smaller quantity. The correlation to this relationship is so tight it has an R-squared >=0.97 (where perfect correlation is 1.0). This is suggests that energy content of wet weight samples can appropriately be determined by finding the ash free dry weight of a sample. A surrogate method that is much easier to do than determining its caloric content. Essentially the dry organic compound percent of the wet weight determines this value. This makes sense when you think about it. The sun powers the formation of organic molecules ... it is in these molecules that all of the energy is stored.

So the dry matter of BG less its ash is very closely as energy dense as the crayfish's. However, I think crayfish are superior prey than BG for a number of reasons (provided a predator is eating them). First they can achieve higher wet weight standing weight. In an unfed unfertilized control Paul Brown et al grew 800 lbs/acre of Northern crayfish in 5 months. BG under the same circumstances would have been limited to around 500 lbs/acre but only if the water was so fertile it would have been as productive as one that is actively fertilized to maintain bloom. So crayfish can produce 60% more wet weight forage per acre than BG. Produce is the key word here, literally the 1 season potential for gain in standing weight is at least 60% more. In a cropped system, this production could exceed the potential standing weight but that is a whole other topic Couple higher wet weight production with 50% more energy in the wet weight and hey we are talking more than twice the energy to consume of (possibly easier to catch) prey. It would just make sense that LMB would ignore BG when crays are abundant.

So why would crayfish have higher energy content than BG? I can think of a few possible reasons.

1. They are benthic organisms that do not need buoyancy and probably benefit from having higher dry weight percentage and negative buoyancy. Nature probably selects for this greater dry weight percentage of wet weight.

2. They don't have as much investment in structures requiring minerals. So the ash content is lower.

3. The lower investment into structures requiring minerals may allow the crayfish to invest more in storing lipids which reduce wet weight are very energy dense (more so than proteins for example)

Great job growing the monster crawdads!

Very impressive that you trained them to drink beer. (Of course it was probably easier to do since they have a can opener on each front appendage!)

Noob question:

Why did you teach them to drink light beer? Wouldn't they gain weight better if you had them drink the full-calorie good beer?

Or are you keeping that beer for yourself?

They just guard craws keeping someone from getting his beer

Man Ive seen the day when Id like to had a couple of them in my cooler to guard my beer, could be a good time, conversation starter, especially after dark.

Now my wheels are turning, this could be a fun experiment.

esshup, I'm with you on the Rusty Crayfish situation. I understand that the goal is to prevent invasive species, but when the rusty is as common as anything else already in our lakes it seems a little too late to hang up posters or think about checking someone's livewell in case one is hitchhiking.

The fear is that they will outcompete smaller less aggressive native crayfish which also is probably true but it seems we are way beyond that already in lakes around here. A large lake loaded with Rustys in Northern lower MI also has seen the population of SMB and YP adapt. The fish are hefty and even the 6-7" YP we would catch would have surprisingly large rusty crayfish folded up in their stomach. This lake has few LMB but I would have to believe the LMB would have an easier time foraging on the largest crayfish than even the SMB do.

I do wonder if rusty crayfish need more calcium content in the water in order to spawn? I know this lake must have tons of natural limestone and high calcium content as every dock or rope left in there will get a gritty stone grime attached to it very quickly. The crays flourish. Lakes with 'softer' ground water chemistry don't seem to struggle with as much rusty crayfish reproduction.

canyoncreek,

The difference that crayfish make is probably more complex in those lakes than just providing food. They probably inhibit recruitment of game and forage fish also. They also modify the habitat influencing the species mix. Where they dominate, it is likely the forage, and particularly the total energy of forage, is increased. It is likely that the combination of fewer predators, more forage, and regular cropping by anglers sustain those fishery's relative performance.

If an introduced crayfish species is so prevalent such that a person can do no harm by introduction to their water ... then there is no reason to introduce them anyway. Why take the risk of transporting a prohibited species? As you prior said, they don't do well in water that has mud bottoms. How much extra will one get ... over say natives ... that are probably suited to making a better living in a pond? Just saying ... it may well be and it is probably true that there is probably a native crayfish that will perform better in most ponds up there than the Rusties. Where is Cody? I bet he could recommend a native crayfish that would produce as much forage in your pond as Rusties ever could without having to commit any crime. Just saying. How we imagine an introduction, (like in lakes where they extirpate native crayfish and make fat SMB), isn't very likely to happen in any member's pond. There are better choices that are not illegal that will perform better or perform as well as Rusties.

oops, now it was assumed I was advocating to do something illegal. Certainly am not. I was only sharing observation that rusties are everywhere already (I hope they moved from bow to bow legally somehow). While I see why efforts to slow spread may still be important, it seems the foodchain has adapted well (or even appreciated their presence in some case) and it might be time to shift prevention strategies back towards other invasives where the efforts might pay off.

Kind of like the marijuana habit. Once everyone was doing it everywhere, they made it legal (at least in MI) and directed efforts at other problems. Probably still not wise on many fronts to encourage widespread marijuana use, and I'm certain it is altering our young people's (changing the forage fish ecosystem) minds, but... Sorry, this is probably a bad analogy..

The original question was about muddy water and phosphorous. Yep, too many crayfish will muddy your water...

Hardly so. I was just making the point that the prohibition on transporting Rusty Crayfish in your state isn't likely holding your water back. Chances are, they are probably there anyway not really helping you out even if they stocked themselves legally. I know you would never advocate doing something illegal. Wasn't my point at all. It would be ironic (or maybe moronic?) to go to the trouble of transporting a prohibited species and only make things less than would have been if a legal path were chosen.

Crayfish are very interesting creatures to me and in retrospect ... as is often stated around here ... "it depends" probably applies to them as well. They are a habitat modifier whose effects can be keystone to shaping a community. They denuded the vegetation in the lake that esshup mentioned. This probably impacts pan fish population structure where crayfish replace pan fish as prey. To be sure, changing where the nutrients are utilized have an impact on water. When they aren't going into macrophytes, nutrients support competitors like phytoplankton or other types of macrophytes (for example the grass blade blooms wbuffetjr is observing). Their contribution to nutrient cycling is noteworthy but I can see where this effect could be excessive (possibly detrimental) in water with excessive nutrients.

Just a note on what happened to my little pond (1/4 acre). It was so full of crawdads that all you needed to do was dip a pole net in and you would have caught a couple craws. Water looked like a mud puddle. Then new 1 1/2 acre pond was made right next to it stocked with bluegill, bass and catfish. Within 2 years we had green sunfish in both ponds. The green sunfish ate all the craws. There is not a one to be caught. Also green sunfish have over populated and are only 3 inches long. So in my opinion I would say a pond with bass would keep them under control. One note that I should say is there is no rock or trees in pond so they have no where to hide.