Help! Overrun with invasive bullfrog tadpoles

[SheWanders]

I live in Oregon where bullfrogs are an invasive species. Two adults found one of my ponds last year and now we have hundreds (if not thousands) of bullfrog tadpoles. I want to remove them as they are detrimental to the native frog species that are also present on our property. We've had no luck netting them in any quantity. This is a large, lined pond - about 25' x 15', 3.5-4' deep - connected to a larger pond by a small stream. The larger upper pond does not have any tadpoles - just goldfish. The lower pond with the tadpoles also has goldfish and a few bluegill. We also want to tackle the huge water lilies that have gotten out of their pots and roots are now floating on the pond surface.

What I'm thinking: Set up a couple of large containers as holding tanks with pond water and a aeration pump. Lower the pond level gradually. Send my husband into the pond in waders and start netting. Dump the contents into a container and separate out the fish from the tadpoles. Cut out and remove water lilies as needed. Clean out the muck and any remaining creatures. Refill (well water) over a couple days.

Questions:

1. How do I empty the pond without sucking out critters? I have a sump pump that I could fit with some screening. Will that work?
   
   
2. After re-filling, I can turn on the pond pump to mix the clean well water with water from the upper pond. The pump circulates water from the lower pond to a waterfall in the upper pond. Water flows to the lower pond from the upper via a small stream. I don't want to risk the health of the fish in the upper pond. How can I safely manage the refill without losing fish?
   
   
3. Anything else I should consider?

 

[WaterGardener]

I'm surprised the bluegill don't eat the tadpoles. Seems as though they should. Stop feeding your fish, if you are, and see if they will help with the population control.

Or get some orfes. I raised mine on tadpoles and mosquito larva that I netted out of a waterlily pool. They love them.

From what I have read, tadpoles are a favorite food of bass.

Does your pond have room for a few more fish? They might solve your problem.

 

[bagsmom]

If the bullfrogs are invasive in your area, I would contact your local branch of the Department of Natural Resources. They will likely have some tips for you!

 

[rcoad]

https://www.dfw.state.or.us/conservationstrategy/invasive_species/bullfrog.asp

 

[Jerri]

I live in Oregon where bullfrogs are an invasive species. Two adults found one of my ponds last year and now we have hundreds (if not thousands) of bullfrog tadpoles. I want to remove them as they are detrimental to the native frog species that are also present on our property. We've had no luck netting them in any quantity. This is a large, lined pond - about 25' x 15', 3.5-4' deep - connected to a larger pond by a small stream. The larger upper pond does not have any tadpoles - just goldfish. The lower pond with the tadpoles also has goldfish and a few bluegill. We also want to tackle the huge water lilies that have gotten out of their pots and roots are now floating on the pond surface.

What I'm thinking: Set up a couple of large containers as holding tanks with pond water and a aeration pump. Lower the pond level gradually. Send my husband into the pond in waders and start netting. Dump the contents into a container and separate out the fish from the tadpoles. Cut out and remove water lilies as needed. Clean out the muck and any remaining creatures. Refill (well water) over a couple days.

Questions:

1. How do I empty the pond without sucking out critters? I have a sump pump that I could fit with some screening. Will that work?
   
   
2. After re-filling, I can turn on the pond pump to mix the clean well water with water from the upper pond. The pump circulates water from the lower pond to a waterfall in the upper pond. Water flows to the lower pond from the upper via a small stream. I don't want to risk the health of the fish in the upper pond. How can I safely manage the refill without losing fish?
   
   
3. Anything else I should consider?

Rake out Lillie’s on top of water. 60% of surface should be under cover or you will have algae crazy like, unless of course you have fish who eat it. I take out the xtra in a few of my ponds- the he others have enough fish in them. Wait until frogs mature to catch at night. Put more fish in bottom pond to eat tadpoles. That’s why there are none in upper ponds- fish to tadpole ratio. Do not drain pond. You will have to establish eco system again and that takes about a month or two.

 

[Jerri]

Rake out Lillie’s on top of water. 60% of surface should be under cover or you will have algae crazy like, unless of course you have fish who eat it. I take out the xtra in a few of my ponds- the he others have enough fish in them. Wait until frogs mature to catch at night. Put more fish in bottom pond to eat tadpoles. That’s why there are none in upper ponds- fish to tadpole ratio. Do not drain pond. You will have to establish eco system again and that takes about a month or two.

There is also: a big enough net/mesh material with metal washers sewn to bottom to hold down as each one of you takes one side and move around pond as opposites. As in the great koi pound captures of Japan- only you’ll do it for tadpoles. The Lillie’s will be a hinderance but groundcover cloth is good for this. It is tough and will not catch to badly on the plants. You can push them to side and then net them out. Maybe