Several Large koi disappeared over winter

[Rosanna Kott]

I had around 20 larger koi (average 1.5ft long) and several smaller koi from a couple inches up to 8 inches just disappear from my pond over the winter. I'm in Michigan, and my pond is natural spring flowing water with a small over flow that has a screen. It is about 50ft by 20ft, and 2ft to 5 ft deep (varies) and is peanut shaped. I have had problems with herons, but never noticed any tracks in the snow all winter. I know they were all there before the first big freeze. We had several thaws over the winter, but my koi generally stay in the deepest part when its cold and so I never stressed over not seeing them, thinking they were in hiding under the sediment. I only have a handful of fish left, 3 largest being about 12 inches. No scales, no carcasses, no sign of anything happening. I don't have muskrats. We do have eagles in the area. Is it possible they took all my fish , and if so, how do I deter it from happening again?

 

[Lisak1]

Welcome to the GPF! Sorry that your first post is such a distressing one!

Is it possible that your pond water was high enough that the fish were able to get over the screen and into the natural waterway? I"m assuming that's what you mean when you say "natural spring flowing water". It is possible that predators took the fish without leaving any trace, but it seems odd that they could take them with the pond iced over.

Can you post some pictures?

 

[Rosanna Kott]

Welcome to the GPF! Sorry that your first post is such a distressing one!

Is it possible that your pond water was high enough that the fish were able to get over the screen and into the natural waterway? I"m assuming that's what you mean when you say "natural spring flowing water". It is possible that predators took the fish without leaving any trace, but it seems odd that they could take them with the pond iced over.

Can you post some pictures?

 

[Rosanna Kott]

There is no way for the koi to "escape" the pond because the outlet is a 10" culvert pipe that has 12ft of land between the pond and the other water source. I will post pics tomorrow, but my husband and I are truly stumped. This is our 3rd winter with the pond and have never lost a fish except for 1 last summer that was the victim of a hero n spearing it with its beak then leaving it lay due to it being too large to carry and we scared it off. The water was open off and on throughout the winter due to the numerous thaws we had and the flowing water. So an eagle is the only thing we can think of that would take them with no tracks or visible remains.

 

[Rosanna Kott]

I have the screen off in the picture and water level lowered due to some cleaning this morning.

 

[j.w]

@Rosanna Kott
Yes if you have eagles flying over that open unprotected pond they have a birds eye view of the koi and could swoop down easily and grab koi. The thing that would protect them would be a net. I had to do that myself and I bought a fishing net online to protect mine. Have it up on poles so I can get in there if I need to.

 

[Faebinder]

This is a predator until proven otherwise.

If you wanna figure out what kind, you will need to put a camera. Bet it still comes around. Predators prefer the bigger fish.

 

[Rosanna Kott]

This is a predator until proven otherwise.

If you wanna figure out what kind, you will need to put a camera. Bet it still comes around. Predators prefer the bigger fish.

 

[Rosanna Kott]

We had a camera up for about a month but caught nothing, however, there has been no more fish taken either. Not since I noticed that they were all missing in February, but hoped they were just hiding, which wasn't the case. I checked the entire pond yesterday. I'm going to put up a net and add more underwater hiding places then hope for the best. Thank you for your help.

 

[Tula]

Welcome, but sorry for the loss of your koi. You say you don't have muskrats, what about mink or otters?

 

[mrsclem]

Welcome Rosanna- If you have eagles, especially a nesting pair, then your pond has likely become their grocery store . We have eagles, osprey and hawks here and even with the netting up, they keep trying. They just cant resist the sight of a large brightly colored fish snack. A gill net suspended several feet over the pond should solve your problem. You have a very nice looking pond. I wish we could have done something similar.

 

[Gemma]

Welcome to the group!

Sorry you lost your fish! ...if not a predator, could they have been stolen?

 

[Rosanna Kott]

Welcome, but sorry for the loss of your koi. You say you don't have muskrats, what about mink or otters?

 

[Rosanna Kott]

We do have mink, but no other that we are aware of. It's just hard to imagine a mink taking that many large fish with so much as a scale left behind. There is a nesting pair of eagles about a mile North, they nest near the school in town. We actually watched one come through behind our barn within 20 ft of us as it swooped in and snatched a squirrel from a tree, so I am going to lay the blame on the eagles at this point, and do my best to deter them. They have a ton of natural water to fish from closer to them (2 rivers and a large dam area) but since it was frozen and my pond was not many times throughout the winter, my fish were the victims I guess. Thank you for the compliment on my pond, it is still a work in progress, but I am proud of what we have accomplished so far. Still so much more to do.

 

[Tula]

Well, at least if it's eagles, you can net your pond to deter them. Mink are the most difficult pond predators to deter and I read on another forum where a person lost 100 koi in one week to a mink!