Pond Boss Forums MANAGING AN EXISTING POND Evaluating and adjusting fish populations Gravel Pit Trout Stocking

OK, I have peaked an interest in a new chain of old gravel pit lakes in my area. I spent all last summer exploring and fishing the deepest and most hidden lake of the bunch. Its about 33 acres and maxes out at about 75 feet deep. The shore is covered in steep deep drop offs. There is a small sunken island 10-25 feet deep and the lake is scattered with coves. (see picture). Its got a pretty good population of LMB, BG, spotted bass, and possibly (I have yet to see) northerns. There are many small forge fish of unknown species as well.There is much structure like logs stumps logs and cars. There is also submergent vegetation less than 1 foot covering most of the bottom with some sections with tall plants. There is also open sandy sections. There is some small drainage flowing into the lake. Since its a gravel pit it is spring fed in multiple locations. It is also quite cold even in the summer. Maybe 60-65F max at the surface. I have yet to measure the exact temperatures (I plan to do this this summer along with the alkalinity and dissolved oxygen). I don't see any algae or emergant vegetation. The water clarity is phenomenal, some days you can see down over 20 feet. It always has a light blue turquoise tint. I had the idea that maybe I could stock it with rainbow trout but I am no expert. I'm also not sure how many or what sizes. (I was thinking a fall plant but I'm not sure. I wouldn't mind waiting till next spring.) What do you guys think. Hey and if not trout, what other fish do you think could be fun? Walleye? By the way I'm in southeast Michigan if that helps.

-Mitch

I'd stock it in a heartbeat. Even if your surface temps are a little bit higher I'd think you'd be okay. I'd stock this spring or fall if I could. Rainbows would be perfect for this little lake.

According to Michigan DNR, if it has permanent inflow/outflow, then a stocking permit is needed, even for private waters. The permit is required and if it is not in hand when the fish are stocked, then the person stocking the fish can get in just as much trouble as the owner of the pond if caught.

Just a FYI..............

YP would also thrive in that body of water along with RES

Is that a submerged car in pic 4?

Is it illegal if it only has an in flow (its sometimes doeesnt even flow in when its dry. Its a drain from the parking lot i think)

Ya there are a few in there and supposedly a crane and other construction equipment.

HSB and crappie would be nice additions as well.

Mitch -

With all those folks living in that apartment complex next to the pit it is likely that _someone_ will notice the "new fish", no? Just seems likely that it won't take long before word gets round the new fish in there, and then the DNR is going to come around. Happens around these parts lots.

Can your DNR up there tie the Rouge River into that BOW? If so, that could be a problem with respect to not obtaining a permit. You might look around to make certain there are no creeks or flood areas that could cause an issue.

I was first going to talk to the apartments before following through with anything. I have never seen another soul on the lake other than myself. I'm about 99% sure there is no connection to the Rouge but before i continue with anything I will check that as well.

Hey thanks for the heads up. I'm gonna double check all of that as soon as the ice melts.

Does anyone know how many should be stocked?

For 33 acres, that is a lot of water to be stocking trout. The HOA would probably have to help defray the cost. The trout should generally hang together as a group especially if they are fed pellets in one area. The trout will eventually find the feeding area. Other fish will likely lead the trout to the feeding area. If you stock 10 per acre that is 300 trout. Your 33 acres is likely at or near carrying capacity so adding trout may result in added competition of existing fish. If I were doing it, I would be removing one bass for every trout stocked to help minimize chances of food shortages. Since the pond has bass don't stock any smaller than 8". Better size with bass present for trout survival is 10"-12" and even some larger.

There are numerous trout farms in MI. One place in southern MI to check for selling you some trout is: http://www.springvalleytroutfarm.com/
They used to sell fish but now it might be only a pay for fishing place. Call them for stocking advice.

Repeat of the note added to my above post.
Your 33 acres is likely at or near carrying capacity so adding trout may result in added competition of existing fish and new fish. If I were doing it, I would be removing one bass for every trout stocked to help minimize chances of food shortages.

So basically remove 300 bass and add 300 trout.

""So basically remove 300 bass and add 300 trout.""
That was just a suggestion. The numbers can vary based on budget and availability. However for the best survival and success of the trout so they do not have as much competition from bass, remove one bass for each trout stocked. The other factor that could change the ratio is if the trout are feed pellets each day. Then I would remove 1 bass for around every 5 trout stocked.

Adding predator fish on top of existing predator fish community generally puts too much competition on the food balance of the lake/pond and the entire fishery as a whole SUFFERS - declines. The system is able to produce a specific amount of food. Overcrowding the number of predators per acre never results in a good balance and all have less to eat - growth slows.

This summer I think I might have some massive evaluations to do. I need to figure out how many fish I really have in this lake. Its a little big to fish out by hand and I have no idea how I can evaluate the current population. Any ideas?

Professionally the best evaluation is by a fisheries biologist with proper equipment that usually means electroshocking equipment. Electroshocking does have its bias in fish sampling.

IMO the best economical way to evaluate the lake for sportfish is to fish it with a wide variety of methods and lures. Wide variety is very important to provide the best results. Wide variety means all types of live bait and various lures - types and sizes. Each lure type and how it is fished has an inherent bias toward collecting certain species.

Knowing well the panfish and forage fish populations is very important. MOST IMPORTANTLY RECORD EVERY FISH SPECIES CAUGHT, ITS LENGTH & BAIT USED. Angler surveys are a very good way to check the species and most common sizes of fish present. If you are the primary angler then it takes lots of time.

At a HOA meeting, tell them what you are doing and you would like written data for whenever they fish so you can better evaluate the lake for them. The more help you get the better the results. Some of the best data can come from kids bobber fishing with worms and live baits such as worms, crickets and grasshoppers. Encourage them to help you in the summer when they are off school. Maybe give them prizes or an angling trip with you for those with the most efforts. Spending a little money on kids prizes saves you time and provides good data.


For the smallest fish use some baited fish traps. A good place to fish them is near some cover. Then use some of the small trapped fish as bait for sampling larger fish.

One of the important things you should be doing is to be taking weekly secchi disk readings. Build your own secchi disk.
http://www.secchidipin.org/?s=secchi+disk
http://rmbel.info/how-to-use-a-secchi-disk/
This data will help calculate the productivity of the lake. The productivity knowledge helps evaluate how many fish are in the lake as far as natural carrying capacity. This in turn allows one to estimate how many bass or fish to remove/harvest per acre.

The secchi disk depth provides a low "tech" method for assessing the clarity and relative productivity of a lake. Productivity determines the carrying capacity and a rough estimate of allowable harvest of a pond/lake.

Clarity is affected by phytoplankton, zooplankton, soil particles, bacteria, and other organic detrital materials suspended in the water. However, Secchi disk depth is primarily used as an indicator of algal abundance and general lake productivity. Although it is only an indicator, Secchi disk depth is the simplest and one of the most effective tools for estimating a lake's productivity.

Read and learn about pond/lake carrying capacity.
http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=92440#Post92440

The only problem I have with this is that that HOA only consists of a few older couples. It is a very small condo complex. There is very little open shoreline for fishing and no boat launch. I am lucky enough to have a small canoe to fish out of. With a lake of this size and depth there is no way I could come close to recording every fish. And how would I know if the same fish is recorded over and over again. On a good day I am only averaging 10 bass in 5 or 6 hours because i haven't learned to fish the lake well enough. These fish are very finicky.

You record every fish you catch, not every fish in the lake. Use different angling methods. Once you catch 15-25 bass and get their lengths. Quit fishing for bass and fish for other species. Use light line (4lb) and live bait if the water is clear. Your goal is to catch and measure as many different fish species as you can.

You have a depth finder?. If not buy a used one on ebay. Learn the bottom contours and structure in the lake. Add and strategically place some of the homemade structures shown in the Archives. Artificial structure will concentrate the fish in to smaller areas to fish around. Locate your hidden structure with GPS and depth finder. A wide variety of fish species will use the structure.

In a lake this size you will very rarely if ever catch the same fish twice. You can mark the fish you catch using the fin clipping method of marking fish if you think you are catching the same fish.

https://www.bassresource.com/fish_biology/fin-clipping.html

Thank you so much Bill. I will get on this right away!!!