Otters raiding garden ponds

There are an increasing number of cases where otters are taking goldfish and koi from garden ponds. Otter numbers are on the up, and they are on the look-out for food. They might already have taken some of your fish, when you blamed a heron.

What is the real level of risk to your pond and can you do anything about it?

The otter increase
Otter numbers in the UK had dropped very low by the 1970s, partly due to the effects of certain pesticides. Since then, due to safer use of agro-chemicals and deliberate protection measures for otters, their numbers have steadily increased.

In our area (Severn Vale and Cotswolds/Upper Thames) surveys between 1977-86 found no sign of otters across all 114 sites checked. Yet by the survey of 2009-10 otters were found in over 60% of those sites, a remarkable recovery[1]. Numbers have continued to increase since then, and there are reports of otters in virtually all English river catchments now. There are healthy populations of otters in Wales and Scotland too.

Garden pond raids
From my own experience in our locality, I had only been personally aware of two possible cases of fish being taken from the late 1980s up to 2013. One of those was from a large pool close to the River Coln, where otters were suspected. The other was from a fish stockholder, where mink were the most likely culprit.

However, I now know of at least seventeen cases since 2014 where otters have been confirmed or suspected. These occurrences have been in three distinct areas, two in Gloucestershire (Minchinhampton, near a small tributary of the River Frome; and Cheltenham, near both the River Chelt, and Noverton Brook), and the other in North Wiltshire (one near a feeder stream for the Cotswold Water Park, and the other on a tributary of the River Ray near Swindon). It is noteworthy that ten of these cases were in town centre gardens, some up to 500m from the nearest stream. There have also been reports in newspapers of otter attacks on garden pondfish in a number of other parts of the UK.

How would I know if otters had been in my pond?
Otters will often visit between dusk and dawn (though feed during the day too) and most customers affected have been aware that something had happened by the following morning. In some cases substantial fish remains have been left partially eaten at the pondside, with large chunks removed from koi. Even big koi (60cm plus) have been taken. In many cases virtually all fish have been killed or eaten on one visit. In other cases some large koi have been left in the pond with severe wounds to the body or fins. (This is unlike heron attacks, where fish over 50cm are less likely to be taken; wounds tend to be spear shaped or in parallel markings on each side of the body; and where many fish escape, frightened into the depths.)

Otters are substantial creatures with brownish coats, and can be a metre long. They are capable of dislodging stones at the pool edge, and knocking planting baskets off the pool shelves – one customer was convinced that the damage to the pool edge could only have been done by a human… until they saw the otter swimming in the pond.

If otters have been in the area, they can leave patches of their distinctive tarry waste (spraints) on nearby rocks/paving. This has a strong, slightly floral odour and may have scales and bones in it. This is unlike mink which are smaller (up to 60cm long), with much darker coloured coats, and whose waste (scat) is tubular, just over an inch long, and smells unpleasant.

Is my pond at risk?
If neighbours have had otter problems then you are most definitely at risk. Otters can travel many miles within a territory, and may not return to an area for some months, but they are likely to revisit. From the reports I know of, if you are within 500m of a stream or river, then your pond is at greater risk. If otters get a taste for garden pondfish, then perceivably they may, like foxes, look further afield in towns and cities for food.

What can I do to keep otters out?
It is uncertain what alerts the otters to the presence of garden ponds, but they are known to have very good senses of smell and hearing. Perhaps they can hear garden waterfalls and fountains, or maybe they can sense the traces of fish aroma coming from the pond surface. It certainly won’t help to leave fish food (pellets or sticks) outside near the pond, as these have a strong smell.

Angling fisheries have had increasing problems with otters, notably on carp fisheries, and suspect that reduced numbers of wild fish in some streams (possibly due to predation by cormorants or signal crayfish), and increasing densities of otters, might also be driving otters to look further afield. Fisheries have had to take substantial steps to keep them out. Certain designs of heavy-duty fencing have worked, usually in conjunction with a powerful electric line (the thick otter pelt gives them some protection from lower powered types)[2]

Ordinary pond cover-nets and heron deterrents (see the post on Herons) are unlikely to have any impact. Wire mesh covers may help, but are of course very unsightly.

A few customers have been so upset by an otter attack that they have decided not to restock with fish, whilst others are taking a chance and restocking with a few low value fish. There is no doubt that otters will impact pondkeeping in future, with at-risk ponds less likely to be stocked with ornamental fish.

Useful links
[1] Environment Agency Survey (pdf)
[2] Fencing to keep out otters (pdf)
Telling the difference between otter and mink
Conference Report on Otters and Fisheries (2012)
Otter fact sheet


9 thoughts on “Otters raiding garden ponds

  1. We have lost one or two pond fish over the last couple of weeks. On each occasion, the fish head was left on the lawn next to the pond. We tried to protect the remaining dozen fish by netting the pond. However, this morning we found three destroyed fish remains and all remaining fish gone. Originally we thought it could be mink but now realize it may be otter. We are about 1000 meters from a small river tributary.

    • I just posted my story yesterday upon actually seeing an otter emerge from my garden pond in the early hours. We live in Fife, Scotland in a village on the main road and have had the pond for over 30 years now with only concerns over seagulls and herons so have several nets which have extremely strong netting fixed onto aluminium frames. We chose the aluminium frames over the steel ones to make it easier for lifting when necessary which unfortunately made it easier for the otter to squeeze under so now we have a series of heavy stones and stone garden ornaments placed to firmly hold the frames down! The pond is positioned in the front garden of the house so we could keep a very close eye on it, however had it been in our huge back garden, then I would never have seen the otter emerge in the very early hours of yesterday morning. At first I though it was a cat in the pond until it emerged with its short legs and built it was easily identified in the strong security light I had switched on. I still find it hard to believe and wish I had got a photo of it but the shock of seeing it, then finding my once beautiful, mutilated fish with a hole in their bodies where the kidneys and liver had been ripped out of still shocks me. My neighbour 4 houses away has a large deep koi pool with no netting so I am going to tell him to beware. I have no idea if I am the only person in Scotland to be targeted but I am sure there may be others. The otters you see on the TV look so cute but in reality they are a vicious and wasteful killer only eating the liver and kidneys, occasionally the head and a chunk of the body. For some reason it left 2 lovely fish in the flower beds unmarked just to die for the hell of it! Not a great idea to introduce it again, as in the past it was hunted for its destructive behaviour. This is my opinion and I am a caring person who rescues unwanted animals and am always picking up wild animals and birds in need of help to take to the SSPCA.

  2. I spent several hundred pounds on orfe, carp etc in March only to find an otter present within days. I had previously not seen an otter but a river runs literally yards from the pond. Whilst l lost most of the gold en orfe a small shoal has survived and I have not seen the otter for two months. I have not seen any carp or koi since. I think the otter must have got scent from the newly introduced fish. Will now consider stocking with orfe, possibly Rudd but definitely not expensive or ornamental fish.

    • Sorry to hear this. The research I’ve seen shows that otters vary in their hunting patterns for fish types and sizes, with no clear preferences. It will be revealing to see which of your restocked fish fare best.

  3. Just had my pond cleared out after 5 years. No river for nearly 10 miles. All the plants knocked in with slash marks on a Lilly. 3 fish scales left on paving. Wondering when to restock. Kois and orfe. Cromer norfolk

    • I’ve found otters to access areas by relatively small streams and ditches, so no adjacent river is necessary. As they may well revisit, there is unfortunately no guarantee that replacement fish won’t be targeted too. Orfe and rudd can be fast swimmers, so might be a fraction less easy for otters to catch than slower koi and goldfish, though I suspect all fish varieties would still be at risk.

  4. I live in Scotland in a village next to the main road. Last year I bought protective heron nets knowing my fish would be safe from seagulls and herons. The pond is located in the front garden so we can easily check on the fish night and day. This morning I woke at 1.10am for the toilet, sadly didn’t check on the fish then, and went back to bed but couldn’t sleep for some reason so at 2.30am I got up to check on the fish and could see there was some sort of turmoil in the pond. When I put the security light on I was shocked to see a broad, flattish, furry cat sized creature in the pond which managed to struggle from beneath the nets which are fixed on metal frames and then moving very clumsily, escape under my front gate! It was definitely an otter with the way it moved, shape of its body etc. I decided to go out onto the pavement to see if it was still there and sadly I found my best and biggest golden carp lying mangled on the pavement with kidneys and liver removed. I lifted it with a shovel not wanting people to see this sight in the morning and buried it along with a headless 6″ golden orfe I had just had 2 weeks which I noticed at the side of the pond on the concrete. I put heavy flower pots on top of the corner of the aluminium frames and of course didn’t sleep again. This morning I was dismayed to see my beautiful tri coloured carp in the flower bed with kidney and liver ripped, out then a little further on in the same flower bed , 2 large and nicely marked shubunkins, unmarked and just left to die. At .2.30 this morning I did not realise other fish had been attacked and never thought to check the flower beds but I could not sleep, kept looking out at the pond so I am now realising that had I looked out at 1.10am, then I may have seen it busy at work and perhaps saved some of my fish. Herons swallow fish whole and don’t rip the kidneys and liver out which an otter does. What a wicked and wasteful creature to re-introduce which doesn’t make any sense. No wonder they were killed years ago due to their destructive nature. Had the whole fish been taken for a meal then ok, still very sad but not so wasteful, but to leave pure destruction just ripping out liver and kidneys with also 2 fish unmarked but just left out to die has made me so angry! I am now going to do a part water change to see if I can see if any of my fish are still there and put the heaviest flower pots on the frames. Can anyone tell me who I need to get in touch with, as apparently a National pot of money is available for electric fencing to prevent otter attacks on ponds? This morning I am getting something to block the space under my front gate which is approx 4″ high which my cats can’t get under and I was amazed that the otter was able to squeeze itself below it! My neighbour still cannot
    believe I saw an otter but it was definitely one as I saw it so clearly when my strong security light was on.

    • Sorry to hear of your fish losses. The damage sounds like an Otter, though Otters are considerably longer than cats (mink are around cat length). Although Otters were deliberately reintroduced in a few places, that was some years ago and only to a limited extent. The increase in number is more likely to be down to the end of use of certain pesticides, and lack of control. As with deer, the problem comes when the numbers increase to levels that are considered to be too high, but there is controversy over whether and how to cull the numbers. As Otters are a European protected species, I can’t see culling being an option in the near future.
      There is no pot of money for fencing to protect garden ponds. In England there may be limited funds to protect commercial fisheries funded by the Environment Agency from rod-licences, and sourced through the Angling Trust

      • Thanks for your reply. The creature could only have been an otter as it was mid brown in colour and a fair size. The body would have been a bit longer than a cat but it was a chunky animal with very short legs. I have 5 pet cats and all are different sizes from small and petite to a really massive male so when I mentioned length of a cat I was possibly thinking of our Billy! I have seen otters on the TV and definitely it could only have been that. I have seen mink before, but not around this area, and they are a slighter creature altogether so there was no mistake with my identification. We have weighted down the pond frames which are aluminium and chosen by us for ease of moving for access to clean the pond so hopefully that will help. The security light is now set to come on during the night when we sleep as the otter moved as fast as it could when the light was switched on from inside and was already on its way by the time I actually opened the house door. If we still have problems then I may think about getting or borrowing a terrier from the gamekeeper that will sleep in a kennel near the pond at nights to protect the remaining fish. Our large German Shepherd is too soft and sleeps too well to be of use in this instance!

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