Water Wolves of Water Gardens - Mink

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May/June & July/August 2007

Jamie Beyer

When the ice thaws off our midwestern water gardens, it is simply a wonderful time of the year. Things are warming up and everything starts to grow again. How did our Koi and goldfish survive the winter? If we had done a proper job of leaf cleanup in the fall and maintained some circulation in the pond to keep a hole open, then our fish should be fine.

Wow, it is discovered that all of your fish that you’ve had for many years are gone! Not even any fish carcasses are found! What possibly could have happened? The raccoons that raided our bird feeders last fall and winter must have eaten them. What else could it be because we have not seen any other kind of critter around?

More than likely the animal responsible was a mink. They can slip in and out through the ice layer by way of the hole that is maintained. They can do this silently, take a fish, and then slip out without leaving any obvious evidence that it was there. At one time, there may have been a few scales or some mink tracks left behind but if you do not suspect a problem, why would you look for evidence?

These water wolves of our water gardens can be devastating for our clients especially the ones that view their fish as part of the “family.” It is amazing how often I have seen the evidence of mink predation and the client thinking that their fish are just hiding. These little critters are silent killers leaving very little evidence so it is tough to know they have a problem until it is too late to do anything.

Almost without fail, most water gardeners do not know that mink are present in their area. This combined with the fact that they are nocturnal, that is, being active primarily at night – they will not be seen or even suspected. Occasionally, mink may be active with some daylight but it is still difficult to detect them because they are small and move swiftly.

They can kill and eat the largest of our fish as well as the smallest. They are very efficient swimmers that can stay underwater for several minutes – even cold water. When it is cold, mink are the most efficient killers because the fish are lethargic due to the lower water temperatures. Whereas the mink are warm-blooded and can swim relatively fast to catch a fish. During the summer, it is a different story. The exact opposite is true and most fish can escape their jaws especially when “structure” is added to the pond.

The best structure is of the type that the fish can hide in, behind or under. A good example is black plastic storage crates that also serve a dual purpose to hold plant pots up off the bottom. Larger fish may need something else like plastic barrels that have been cut in half or have large enough holes cut in them so the fish can swim in and out easily. Structure may also be created with rockwork or underwater caves can be purchased (ex. Koi Kastles). The point is to provide something that the fish can escape from the mink’s teeth.

Mink occur over almost the entire United States and Canada with the exception of the desert southwest and tundra areas. A mink’s basic habitat requirement is a suitable permanent water area. So, water gardens that are within a mile or two of naturally occurring water, like a creek or lake, are more susceptible to having mink predation. However, there are instances where a wandering mink will find a pond further away. If a creek is within a stone’s throw of a client’s water garden and not in the desert southwest there is a very good chance that a mink will show up sooner or later.

There are a few things to look for to determine if a mink is preying on a water garden’s fish. If the fish are large that are being eaten, then scales will be evident. The mink has to drag the fish out of the water to eat it and in this process, scales will be left behind. There may be some fish parts left over but do not count on this. Mink track may be in the snow or mud. It is possible that their wet footprints will be left behind in the morning on the rocks or some hard surface but check for these in early morning before the tracks evaporate. Remember, nothing else will be disturbed around the pond. A raccoon will leave all kinds of disturbance, in most situations, especially if all the fish have been taken. One last thing to look for is how easily the fish are spooked. If they seem agitated then there is a good chance that a predator has been after them.

To stop mink predation you have to react immediately otherwise by the time you have rounded up the necessary tools to deter mink it may be too late for the rest of the fish. So, I always recommend to dye the water black the DAY you suspect a mink problem. This means either the pond owner needs to have some dye on hand or you need to have it on hand for your clients. For pond owners that I feel are vulnerable to mink, or even some other predator, I always advise them to stock the stuff. If they depend on me having the dye and they cannot get in touch with me immediately could spell certain death for more fish the next night. Once mink find a good source of food, they will be back in successive nights until the food source is gone.

I like to use black because it is the darkest. If the mink cannot see their prey then the fish are safe. Dyes made for water gardens will dissipate in time and do absolutely no harm to the ecosystem.

There are not very many good easy solutions for the pond owner that has had a mink show up. After the water is dyed then the next choices are to keep a large dog that has free run of the water garden area 24 hours a day. Keeping inexpensive fish is an option for the future but that is not really a choice at this point. If the pond is covered with ice, except for the circulation hole, then cover it with 1/2 to 1 inch hardware cloth or welded wire. Another alternative is to use a 12 inch high electric mesh fence for a month or so.

The best solution, in my view, is to remove the critter that is eating the fish. Trapping may not be what you can do or would prefer not to do but it WILL work. Contact the local DNR to make sure that you can legally do this. A pest control person/trapper may be able to help if you do not have the expertise.

Of all the critters that can prey on fish in our ponds, mink are the most difficult to detect and to deter. Knowing that they are around and that they can be a predator is the first step in solving the problem. If there is the possibility of having a water wolf problem, make sure that you have black dye on hand. Then, detecting the presence of a mink and permanently solving the problem, is difficult, but can be done.


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POND Trade Author - Jamie Beyer

Author Jamie Beyer

Location Boone IA

Company Midwest Waterscapes

Bio The very popular subject of adding water features to a garden is one that Jamie Beyer brings a lot of knowledge and enthusiasm to. Jamie is a Lifetime...

Read the full bio.

Comments

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Excellent article Jamie -- can you advise on how amateurs can trap mink. We just found our first large koi dead - and we saw the mink carring it away.

Don Untiedt, Plymouth, MN

1. Posted on July 4th, 2011 at 2:32 pm.

By Don Untiedt.

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Don

It is very important to temporarily protect your remaining fish from the mink -- cause he will return on a regular basis. That is why I recommend dying the water black. The dye is very environmentally friendly and will dissipate over a month or so. If the mink can't see them then they cannot prey on them. Normally mink are not as much of a problem with warmer water temps. The fish can move faster with the warmer water. Exceptions are small ponds (where the mink can easily corner the fish) and areas where the mink are desperate for prey.

Now with your fish protected with the dye. You now have time to get the mink trapped. Trapping can take up a week or two to catch the mink. Sometimes you can trap the mink overnight but most times it takes longer.

Boxtraps or livetraps are not very reliable to catch mink so do not consider them. Yes, you can get lucky and catch a young or dumb mink with a boxtrap. There are always exceptions to the rule but do not rely on them for mink.

It is going to be difficult for me to teach you email wise how to trap a mink but I will try. It depends on your experience with traps on how well I can teach you. So the best thing is to find a local mink trapper to assist you. There is absolutely no value to a summer mink pelt. I would offer the trapper at least $30 to catch it for you. It may take a trapper 2 to 6 hours to catch the mink so offer what you think is fair.

The best trap set for mink is to a Conibear (a 120 Conibear) and set the trap in a tube with slots cut in it to hold the springs. Set the tube with the trap in it in water along the edge. You will want to have 2/3 of the trap out of the water and the tube running along the shoreline of your pond. The tube can be drainage pipe, pvc pipe or a mailbox with the end cut out. By setting in the water like this makes it specific in catching mink. Cats or any other critters will not enter the water. Of course, some small stones in the front of the tube will keep the larger fish out.

I have come up with another set using a snare but to find the right snare and for me to describe the set is more difficult.

Foothold traps work but again it would take me many paragraphs to describe the sets that may work.

Good luck! Jamie 

2. Posted on July 6th, 2011 at 8:01 am.

By Jamie Beyer of Midwest Waterscapes.

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Where can I get the black dye?

3. Posted on May 20th, 2012 at 7:19 pm.

By Barbara.

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Here are three places that say they sell black pond dye

http://www.thepondguy.com

http://www.thepondoutlet.com

http://www.pondmerchant.com

4. Posted on May 22nd, 2012 at 9:23 am.

By Cindy Graham of POND Trade Magazine.

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I lost 4 2lb plus size koi and 15 medium size gold fish in 1 night. Do mink come in groups? The pond is about 2 and a half feet deep and has plenty of hiding places for the small fish. The next night the rest of the fish were gone close to 30 in all. I don't see how racoons could have found all the small fish.

5. Posted on April 25th, 2013 at 8:32 am.

By judy kamp.

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Judy:

Of course, I have some additional questions. Was the pond tore up? Plants displaced, gravel moved, etc? A raccoon will do this when it is trying to catch fish. Any tracks? Any fish scales? Any "trail" to the woods? Any naturally occurring stream or pond nearby and how close? Was there any ice on the fish pond? What time of the year did this occur? Where part of the US is the pond located? Are there otters in the area? Is this pond in town? Did you just do a pond/stream clean out right prior to the predation? Did you just shut down a stream/waterfall right prior to the predation?

Without any more information I would say that you may be right -- that is was one mink maybe two. However, otters are very similar in their ability of cleaning out an entire pond of fish. They both are in the Mustelid family which means they are very closely related and have very similar habits but there are differences.

Otters do not venture very far from naturally occurring big water (not much further than 1/4 mile and the water needs to be more than a small creek -- please remember, there are always exceptions to the rule) so without any more info I am assuming that this pond is further than this. Otters "normally" occur in more wild places so if this pond is in town then it would more likely be a mink.

Mink are much more common so I am assuming it is mink just because of this. Both mink and otters are very well adapted at eating fish. That is their main prey item.

Mink are normally loners but in the spring, they can occur in pairs and in the early fall a female can be training her kits.

One mink will prey on large fish as well as smaller ones. They will cart them off to a den to feed their young. They will also cart them off to eat where it is safer for them. There not very many predators that can be so proficient at catching all the fish other than mink and otters. It is also amazing at how mink can carry off a large fish that are bigger than they are. However, there will be scales on the rocks cause a mink will have to drag those big fish. If there were no scales then it just may be an otter.

Yes, mink can clean out an entire pond in just a few nights. I would venture to say you may have been missing a couple of those large fish before you noticed anything wrong. These predators are very elusive and most people have never seen them even though they are living all around us.

Of course, by now the evidence of scales, tracks, trails etc. may be gone. I would still check for scales cause they can last awhile.

The first step at protecting our fish is identifying the predator. That is what we are doing here, of course. Now, how do we protect our fish? That is another discussion.

6. Posted on May 2nd, 2013 at 9:30 pm.

By jamie Beyer of Midwest Waterscapes.

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Lost 6 large fish and 13 large green frogs in 3 nights from my two little ponds. Feeling devistated to say the least. Mink cleaned me out. Have a branch of a river and very small creek behind me. Now that there is nothing left will the mink stop coming? When would it be safe to buy more fish? Don't know how I can ever get frogs back.

7. Posted on May 22nd, 2013 at 4:01 pm.

By Debby.

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Debbie

You are right -- when mink show up they can be very devastating. It is unfortunate that you had to go through it. They will take everything in the pond in a matter of few days. Mink are even more of a problem when the water cools. The fishes metabolism slows and they can more easily be caught by a mink.

Yes, after a mink wipes out a pond they will not be back for a few weeks or a month or two but believe me they will be back sooner or later. There are a couple of things that could affect if they show back up. They also have predators -- man as well as large owls, coyotes, fox will all take a mink. In more urban situations mink have fewer predators.

Another thing that could change if a mink shows back up would be habitat changes. River modifications or construction near their home range could change things.

If I was a betting person I would bet that the mink will be back sooner or later. I know that is not what you want to read but it is a fact. Mink are the most difficult predator to deal with but they do have a couple habits that we can take advantage of. A trapper can be very good at catching them. I would contact a local conservation official and see if you can encourage anyone in the area to trap the mink. We have a lot of mink and you will not be harming the population of mink. You will need to talk to your local conservation officer to get permission to take a mink. They are a protected species and have a harvest season in most states. To take one out of season you will need that special permission which most CO's will grant.

The other option is when you see evidence of mink then immediately dye your water black. If a mink cannot see their prey then they cannot catch them. Our colorful fish are like beacons in the water -- they are a swimming come eat me sign. Native fish are naturally camouflaged -- that is the reason they can survive. So use black dye -- have some on hand and ready to go just in case. The water dyes are eco-friendly (will not harm fish or plants that grow to the surface) and will dissipate over time. I like black dye better cause it creates darker conditions.

Hopefully, the dye will discourage the mink from showing back up or you can have a trapper come in and take care of it while your fish are protected by the dye.

I have some experience with caging fish within the pond (thereby protecting them) during the cold water months. This is an option. You still have the risk of the mink taking fish even when the water is warm and the fish are uncaged. This is normally a problem only in small ponds where the fish can be cornered and cannot escape. This sounds like your situation since you mentioned that your ponds are small.

Finally, you have the option of keeping inexpensive fish and expect the loss of fish occasionally. Not a good option but something to think about.

Good luck! Jamie

8. Posted on May 28th, 2013 at 12:55 pm.

By Jamie Beyer of Midwest Waterscapes.

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This is the third year in a row mink have cleaned me out of my fish. I trapped one two years ago. They are MEAN!!!Be careful!! They smell bad!!! Last year another mink came cleaned me out and I found that they are not eating all they catch but storing them for later consumption. Mine was under my gazebo and after lifting some boards found the mink still there staring at me. I took his "stash" and put 1 or 2 dead fish he stashed every night in the trap but did not get him. This week I saw one that was hit by a car nearby.I am out of things to try.Will high frequency sound work? What frequency? I have neighbors close by and a frequency heard by humans might not be welcome.Any help would be greatly appreciated.

9. Posted on September 4th, 2013 at 6:28 pm.

By Peter.

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Hi Peter.
Just so happens that we revisited this subject in the very latest issue of POND Trade magazine. And YES those mink are crafty little fellows. Follow the link below to get up to date on Jamie Beyer's tips.

http://www.pondtrademag.com/articles/ar-365/

Hope this helps.
- Lora Lee

10. Posted on September 8th, 2013 at 7:21 pm.

By Lora of POND Trade magazine.

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