The Eurasian otter

The otter is a medium-sized predator in the weasel family. It specialises in hunting for food in water, so we find it close to watercourses or in coastal areas.  

It’s body is long and thin, and well adapted for swimming. There is webbing between the toes on it’s short feet, while it’s thick fur insulates it from the cold water, with small pockets of air forming between the hairs. The fur itself is silver brown across the otter’s back and on it’s feet, and lighter on the abdomen.  

The otter also has several characteristics that are adapted to it’s semi-aquatic life, including the ability to close it’s nostrils underwater. It moves elegantly underwater and can dive to a depth of several metres in search of food. It can hold its breath for roughly a minute before having to surface..  

An adult otter can be between 50 and 95 centimetres long, in addition to which it has a tail of 30 – 55 centimetres. It’s weight can vary enormously from a few kilos to nearly 15 kg. 

Foto: Jonas Heland.  

The otter is a nocturnal animal that spends most of it’s time hunting for food in water.  

When not hunting, it sleeps or rests in it’s den, or holt. The otter can either dig a holt itself in earth banks or sandy margins by the water, or can take over a fox’s den or beaver’s lodge.  

The otter can live by the coast, a large lake or a river and needs good access to wet areas in order to obtain food. They are neither social nor especially territorial animals, but have a sort of territory even if they do not defend it to any great extent.  

If the otter lives on the coast, it must have access to fresh water in order to wash it’s fur, so it is only found in coastal areas where it is not far to the nearest river, stream or lake.  

Photo: Siri Hokkstad. 

The otter mostly eats what it catches when diving, which varies according to where it lives, of course. Small fish are an important source of food everywhere, but birds, frogs, small rodents, such as mice, and crustaceans are on the menu as well.  

If an otter is hungry, it may also eat plants, though plants do not seem to be something they prefer.  

Just like the lynx, the otter is a picky species that only selects the best parts of the animals it eats and leaves the rest for scavengers.  

Photo: Even Hønserud Hagerup.

Otters do not become sexually mature until three years of age, after which they can mate at any time. The females come into season every four to six weeks and are pregnant for about two months before giving birth to one, two or three pups in a natal den.  

The natal den is not the same as the holt it normally uses and is further away from the water’s edge, providing better protection for the pups.  

Otters can give birth at any time of year, with the pups being blind and toothless for the first few weeks. They are not big enough to leave the natal den until two months old, when they can start learning to swim. It will still be several months before the pups are good swimmers, so they stay with the mother for a full year before they are big enough to head off and find their own territory.  

Staying with the mother for a year may not seem a lot to us humans, who usually live with our parents for nearly two decades, but it is actually a very long time compared with other mustelids, most of which chase their young away as early as the first autumn, when they are just a few months old!  

Foto: Leszek Leszczynski. 

Otters have what is called a palearctic distribution, which means that they are found over a large area that includes the whole of Europe and parts of Asia. They are also found in the far north of Africa.  

In Norway, otters are found throughout the country, but are only considered a common species along the coast north of Central Norway. South of this, they are relatively rare and scattered, but nevertheless pop up in a variety of locations.  

Researchers are actually very uncertain about precisely how many otters we have in Norway and where they live. We may know more about the otter in a few years when these research projects are complete. 

Photo: Bendik Øverhus Hassel.

At the beginning of the 20th century, the otter was very common here in Norway, and was found near the majority of larger lakes and watercourses, as well as along most of our coastline. The next 30 years, on the other hand, were not good for otters, as otter fur attracted high prices and there was a bounty on their head. This resulted in a recresion of otters, with local populations disappearing in several areas.  

In 1932, the state bounty was removed and there was slightly less pressure on them from hunters, but some hunting continued all the same. Municipalities could still pay bounties and good prices were still paid for the fur. So although the state bounty had been removed, otter numbers continued to fall.  

Change came in 1972, however, by which time there were very few otters left in Norway. The authorities decided to protect the entire population in East and South Norway. Four years later, the population in West Norway was also protected, with national protection finally coming in 1982.  

When the otter was given protection, things did not look good for it, but fortunately there were enough of them to get by. Today, the otter still has protected status and numbers are probably increasing. The species is in the ‘vulnerable’ category on the Norwegian Red List, but uncertainty surrounding the number actually found in the wild makes this a risky assumption.  

Many other European countries had similar experiences as Norway, and the otter has disappeared from several countries and many areas where it was native a century ago.  

Otters do not really have any natural enemies here in Norway, although some marine animals may kill them in certain circumstances. Animals like killer whales, for example, can catch otters in the sea, but this is very rare and insignificant in terms of it’s impact on the population.  

Humans are the biggest threat to otters. Otters can be killed as a direct result of hunting, but many also end up dying as a result of being run over or as bycatch in fishing nets.  

There is a certain amount of conflict with the fishing industry in consequence of otters liking to eat farmed salmon, which are easy prey for them. Even a single otter can do costly damage if it starts hunting inside the cages.  

Photo: Even Hønserud Hagerup.

There is a lot of good information on the otter and we can recommend the following sources for further reading:

• “Otter” at the Norwegian Biodiversity Information Centre
• “Otter” at Store norske leksikon
• ‘Tips oss om du ser oter!’ (Tell us if you see an otter) at the Norwegian Institute for Nature Research (NINA).
• Otter at the Norwegian Zoological Society. 

We have also used them as sources for our information page on the otter.  

This article has been written by Nicklas Iversen, a former nature guide for the Visitor Centre Carnivore Flå.  

Photo: Jonas Heland.