Pond Boss Forums MANAGING AN EXISTING POND Evaluating and adjusting fish populations Keep LMB from Spawning?

New to the forum. I've already learned a lot in reading various topics. Thanks to all of you who contribute.

I am trying to remove the LMB from my pond. The 3/4-acre, 8 ft. deep pond was created two years ago, lined with EPDM rubber and 6 inches of pea gravel, and a small sand beach where the LMB like to hang out. I have a variety of small boulders placed throughout and am getting some vegetation established. There is no natural inflow or outflow of water. I filled from my well and use pond water for irrigation. This only replaces 1/2 of 1% of the volume of pond water each day in the summer, but I have two air-diffuser aerators that sit on the bottom and run 14 hours per day. I live at 6500 ft. elevation in Colorado. The pond warms to about 72 degrees in the summer and freezes over in the winter. I run my aerators in the winter and the fish have all survived.

The pond was originally stocked two years ago with 100 rainbow trout, 300 small blue gill, 20 pounds of fatheads, and 10 large mouth bass about 12 inches long. In mid-June last year, I noticed millions of small minnows. I was elated, thinking my fatheads hit the big time. Unfortunately, they were LMB minnows which quickly decimated my fathead population.

I spent last summer doing what I could to extract them by seining the minnows and trying to catch the larger LMB. Still, I now have about 6 of the 12-inch LMB remaining, probably 30+ that are 6-7 inches which were minnows last year, and probably another 100 that are still less than 3 inches.

The last several weeks the pond has warmed and the LMB appear to be in spawning mode. I have disturbed them as hang out in the shallow sand beach area, hoping that will keep them from reproducing.

I think it is best to eradicate the LMB and restock with fatheads. Does that seem like the right approach? If so, I think that if I can just keep them from spawning that I could pull the existing LMB out over time. I've even thought of electro shock, but that seems expensive and complicated.
The trout have done very well and have grown from 10-12 inches to 16+. I feed them a bit of AquaMax 5 in the spring and fall. I haven't seen many blue gill, but the ones I have seem to be of size where they could spawn this year, but I'm afraid my LMB will clean them out, too.

Any advice on how to manage my LMB population is greatly appreciated.

Thanks!

Tim, you've got your hands full... Trying to completely remove a population of LMB once they've spawn will be nearly impossible. If you do remove all the LMB, then your BG will likely over populate and stunt badly. The pond may stay cold enough to prevent BG spawning, but if it's hitting 72, probably not.

What are your goals for the pond? A complete removal of all fish and starting over may be the best idea. It'll put you a few years behind, but would be worth it over the headaches you'll be facing for years to come otherwise...

I'm with CJ, Seriously consider renovating the pond with rotenone. One needs a pesticide applicators permit to buy rotenone. IMO if you really want the LMB out - bite the bullet renovate. You could spend 2-3 yrs trying to remove the LMB and still have a couple breeders in the pond while wasting 2 or more yrs. Renovate soon and restock in Jul-Sept. Electroshocking is fairly expensive and not a good option since it will not get all LMB esp the 'smart ones' which will likely also avoid hooks. Your relatively shallow maximum depth of 8ft reduces the cost of rotenone product. If you want to further reduce the cost, lower the pond depth 3-5 ft and it will reduce the cost of chemical by half. But you should consider the costs of pumping if you have to drain & refill with a pump. Maybe contact Mike Michell at Queen Of the River Fisheries, Longmont, CO (303-651-2514) for opinions, advice and pricing.

Not sure of this is an option, but you could sell the LMB if you have the right permits.? Just an idea since LMB are in huge demand it seems.?

Excellent advice. I didn't know such a product existed. I think I'll hold off on using rotenone this year and see what happens. Since it is such an extreme solution, I may wait and see if the LMB get completely out of hand before using it. My pond temp is now 63. If the LMB have spawned, I should know soon. Could they spawn later in the summer, too?

Any kind of traps that might work? I've tried a few, but never seemed to catch other than the occasional minnow. They didn't seem interested in my cat food bait.

As for goals for the pond, ideally I am looking for something that is self-supporting. I am not looking to raise trophy fish, and I do little fishing myself. I enjoy throwing fish food to the trout and watching the frenzy, and don't need a lot more from the pond than that.

-Tim

Thanks for the referral. I'll contact him when I'm ready to use rotenone.

Some Fishery Mgt companies will do a partial rotenone of LMB nests during the spawn. IMO you need to get the LMB out if you want to keep RT , BG and FH. Another option is to drain the pond and use hydrated lime rather than rotenone. That does not require any permit in most states.

http://www.catchnbait.com/pinfish-bait-fish-traps.htm - Condo or jumbo for larger fish. Use dog food and fish pellets leave for 1hr to 4hrs and check. You can also make these traps at home if you have time. There are other threads on trapping, but don't know if people are trapping LMB. I am using this type trap to catch sunfish/BG and get a few bull heads time to time.

LMB larger than 2" very rarely enter a fish trap.
Now that you stated your goals; ""As for goals for the pond, ideally I am looking for something that is self-supporting. I am not looking to raise trophy fish, and I do little fishing myself."" Now I'm not so sure you need to exterminate the LMB. I think if you focus your angling on them (all sizes fished different ways live bait & various small lures when trout are deep and not responding to shallow water angling) then you should be able to keep LMB density low enough that is does not detract too much from your stated goals. Note this management method will require significant amounts of angling time each year to keep the LMB to only a few to several fish in 3/4 ac. You may not have enough time to accomplish this. That much water can result in quite a few fingerling each year from 1-3 nests.

Hi Bill,

Keeping some LMB in the pond will likely be where I will end up; not because I don't want to eliminate them, but because it's probably the most practical thing for me at the moment. I will try angling them this summer. They aren't as interested in feeding now as the trout are, but in another month or so I should have a better chance. I also ordered a large seine net which I think will help to a degree, especially when the LMB are already in the shallows.

I actually don't mind having a few LMB in there if I can just keep them from spawning and wiping out my fatheads. The larger LMB pick off a few here and there - not a problem for the vast fathead population that I had. Last year when the LMB spawned, their minnows worked the crevices of the shoreline and completely cleaned out thousands of fatheads to where none survived.

I may end up just letting the LMB do their thing and just do what I can to angle them out of there every year to keep their populations in check. I would guess that LMB minnows are just as good for the trout and BG as fatheads would be.

I have yet to see a pond with LMB that had a self sustaining FHM population. Even in extremely low densities, the LMB always wiped them out. I wouldn't even consider FHM as an option from here on out.

It's my opinion that you want your LMB to focus on eating your YOY BG and nothing else. Keep them focused on eating BG by not adding anymore FHM or adding GSH. Keep your trout fat by feeding them pellets, but they will also feed on YOY BG, particularly when water temps get lower in the late fall and through the winter into early spring when the BG are lethargic but the cold water trout are still active.

I would also continue to trap and fish for as many BG as you can. With a cold water pond like you have, the BG are almost guaranteed to stunt, but you can work hard to not let that happen.

Same here. I look at FHM as a good starter foor for fingerling LMB to get them a great jump on growing to be large LMB.

esshup stocking bass fingelring this week fun to watch...right out of the bucket they start eating the fhm cool to see.

You said, "I would also continue to trap and fish for as many BG as you can." Did you mean LMB? I was intending to grow the BG population. About how many BG should I have in a 3/4 acre pond? Or should I be focused on size?

It all depends on if they can spawn... They may struggle to spawn in waters as cold as yours. But in general, BG often times than not badly over populate in northern colder water ponds and stunt. With you limiting LMB numbers, you will struggle to control BG numbers if they are able to spawn. So you will have to work at controlling them. It's not about fish numbers but about weight. Total pounds of BG your pond can support.

Got it. Thanks for the tips.