Otters in the UK - What You Can Do To Help

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By Grace Yoxon, Director

The only species of otter native to the UK is the Eurasian otter (Lutra lutra) and it is classed as Near Threatened in the Red List. It is a semi-aquatic mammal and lives in many different wetland habitats – rivers, lakes, canals, estuaries, and along the coast. Eurasian otters do not live in groups, just single animals or a female with cubs.

The otter came close to extinction in the UK in the mid 1950s-60s. At that time otter hunting was still allowed but the main cause of the dramatic decline in numbers was pollution from organochlorines, including dieldrin. These were used in pesticides and leached into waterways. As they accumulated in the environment they were taken up by species at the top of the food chain, such as the otter. They were subsequently banned in the UK but not before otter numbers had become dangerously low.

Subsequently a lot of work went into cleaning the waterways and for a while things looked to be steadily improving. As a result, we read a lot in the media about otter numbers increasing rapidly particularly in England and Wales. It is true that there has been an increase in the number of signs but what exactly does this mean?

Otter surveys do not count individual otters but look for secondary signs in the form of spraint (droppings). Selected sites are checked for up to 600m and if spraint is found then that 10km grid square is marked as positive. So what otter surveys really do is map the distribution of otter spraint. Obviously this means that an otter has been there but it does not give any idea of otter numbers, or even if the animal is resident. The otter could merely have been passing through trying to establish a home range.

Otters have vast home ranges and in freshwater systems a male can use about 40km of waterway. So it is perfectly feasible that it may spraint in four 10km grid squares giving four positive records, suggesting that there are four otters rather than one.

We can certainly say that otters are being seen in new areas and even in more urban settings. However, otter populations can only increase slowly and reports that they are “flooding” back into areas are greatly exaggerated. Otters do not reproduce quickly: they do not become sexually mature until about 18-24 months and data indicates that in the wild they die at about 4-5 years old - there will be cases of older otters but this is an average. As the young stay with the female for 12-15 months they do not breed every year so a female may only have two litters in her lifetime. So it simply is not possible for the population to “explode”.

In spite of the difficulty of assessing numbers, it has been estimated that the total number of otters in England Scotland and Wales is around 11,000 (Mammal Society Review of the Population and Conservation Status of British Mammals, 2018). Let us put this into context by looking at three other species listed in the UK Biodiversity Action Plan 2023. There are estimated to be 132,000 water voles, 579,000 brown hares and 270,000 red squirrels. And yet there is concern for all three of these species because of declining populations.

We can therefore see how rare our otter actually is.

Otters continue to face many threats from habitat destruction and careless development, water pollution and reduction in prey availability. The favourite prey of freshwater otters is the eel and numbers of these fish have greatly declined, in some places by about 90%. With the reduction in natural prey otters are having to travel further for food and they are more likely to take fish from people’s ponds. Home ranges are expanding more than the actual number of animals.

There is also an ever-increasing problem of roads with more traffic and otters having to travel further. Indeed, roads are responsible for the greatest number of non-natural deaths of otters and if a female is killed her cubs will die unless they are found quickly. Cubs look very cute when they are small but they have to be reared with minimal human contact and without the company of dogs, cats and other domestic animals. Otherwise they are doomed to a life in captivity.

Pollution too is still a problem. According to a report by the Environment Agency almost half of the rivers monitored exceeded limits for at least one harmful pollutant, including heavy metals and dangerous industrial and agricultural chemicals and there is the cocktail effect of all of these chemicals and also plastics.

So water quality is still a very serious problem and we have been hearing a lot about the problem of raw sewage in the rivers. In August 2019 a report published by The Times stated that many rivers in England are so polluted that they are dangerous for people to swim in. If it is so dangerous that people cannot take the occasional swim then they can hardly be healthy for the fish and otters either.

So is it all doom and gloom for otters in UK?

We have to be positive that things can be done to help these animals and otter conservation is not a sentimental luxury. The otter is an ambassador for a healthy environment – as they are at the top of the food chain and use both the land and water environments both habitats have to be in excellent condition. For an otter to survive it needs clean water and land habitat, plenty of resting/home (holt) sites and minimal disturbance for them to carry on their natural lives. This is much the same for most species, including our own.

A lot of hard work has been carried out since the 1980s but we need to do more to protect the environment. We cannot leave everything to governments and we all have to take responsibility for our actions. We hear about what we can do every day – recycle, reuse, use less fossil fuels, walk more, protect habitat, but how much do we actually do it?

So what can you do to help?

• IOSF needs more people to work in practical conservation such as clearing rubbish out of rivers and off beaches, planting bankside vegetation to provide cover for holts, etc.
• Create more awareness about otters and their role in the ecosystem. When top predators disappear this has a drastic effect on the whole of biodiversity.
• Learn how to survey for otters and send your records to IOSF.
• Always make sure that if you are watching otters you do so responsibly and do not publish actual locations online as this can lead to disturbance.

   
For those who work in the countryside and conservation, develop a project to improve the habitat not just for otters but all wetland species. You can also set up your own education programmes for children and adults. IOSF has our Team Otter programme aimed specifically at encouraging children worldwide to care for their environment and we welcome anyone to join our team.

If you are a student looking to work in otter conservation we have an annual Student Research Grant which provides funds for two students to join a professional otter surveyor for a two week survey and learn first hand more about otter ecology and field techniques.

Together we can make sure that otters really do have a bright future together with all wetland species.

Check out our website www.otter.org and contact us at enquiries@otter.org

Join in IOSF's World Otter Day on the last Wednesday of May each year. It is a day of events worldwide to draw attention to otters, their habitats and the need for their conservation. In 2022 events were held in 39 countries so join in.

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