For a long time, otters had almost disappeared from our environment. Habitat protection and species conservation measures and regulations have happily led to an increase in their numbers since the 90s. This positive development is the result of many years of animal protection and conservation efforts. Unfortunately, the increase in otter numbers has led to conflicts with recreational and professional anglers as well as with ornamental and farmed fish pond owners. Whilst the otter is seen as only a minor pest in the fish farming industry, some areas suffer from significant losses.
How can I protect myself from losses due to otters?
Increasing otter numbers have unfortunately led to more and more conflicts with fish pond owners as well as professional and recreational fishermen. They see their fish to be threatened by these predators and complain of massive losses. Even where natural bodies of water are located adjacent to artificial ponds, otters quickly realise the advantages of the well-stocked ponds. Otters will usually continue to return once they discover an easily accessible source of food. Ornamental and breeding fish farmers in particular suffer from the sometimes very high financial losses. In these cases it is imperative that measures are taken to protect fish stocks.
Preventative measures need to protect the pond from otters. Measures must be taken that either scare otters away from the pond or prevent them gaining access. Otters should additionally be offered an alternative food source to distract them from the fish pond. Scientific studies have shown that fencing off ponds with electric fences is the most effective measure that can be taken.
Startlers should scare the otter away from the ponds. Scent marks, optical measures ("otter scarers") or noise making devices are most commonly used. These resources do indeed scare the otters away at first. However, they quickly realise that these startlers pose no actual threat to them and ignore them. Since they are only effective for a short period of time, if at all, startlers at not recommended by experts.
Keep the fish density low
Otters prefer to eat what they can get hold of with the least effort. And fully stocked fish ponds are a true paradise for these little predators. Otters may even kill more fish than they can actually eat.The lower the fish density in ponds, the less attractive they are to otters and they will go off in search of an easier source of food.
A distraction pond should offer otters an alternative food source. This generally involves installing smaller pools in the area around the threatened pond which are then filled with commercially cheap fish. Because of the high fish density in the distraction ponds, the otters have a much easier time catching their prey and quickly start to prefer these ponds over the primary one. This method generally works very well. However, it is not inconceivable that this artificial feeding could easily increase otter numbers in the affected area. This can then mean that after some initial success in reducing losses due to otters, the otter problems will multiply. However, distraction ponds are useful for nature conservation, particularly where previous ponds have been fenced off and made inaccessible to otters.
Fencing with electric fence
The only method proven to be effective is to enclose the fish ponds using an electric fence! Fisheries associations and environment ministries have confirmed this finding and also recommend the use of electric fences to ensure effective protection against otters. Ideally, an electric fence used for defence against otters will reliably keep otters away from the pond without posing a danger to people or animals. The fence should also be simple and affordable to erect and not look out of place in the landscape. The pros and cons as well as detailed designs for the various electric fences can be found under Otter fence