Long live the otter!

Recent efforts by animal welfare activists have seen the successful reintroduction of the otter, which had previously been extinct since the late 1980s. JOEP DERKSEN reports.

In different patches, more than thirty otters were released in the national park De Weerribben in 2002. These otters originally came from Lithuania and Belarus. Since these otters have been equipped with a transponder, their whereabouts can be monitored. As an added measure, ‘camera traps’ keep track of the well behavior of the otters. The first positive results were announced two years later: the arrival of the first four otter offspring in the wild. Nowadays, three generation of otters live in this region.

Adult otters can measure up to 140 centimeters in length and weigh a total of twelve kilos. They are well-adjusted to life in the water and predominantly eat fish, such as ale, carp, salmon, bass, and pike. But amphibians are also on its menu; an otter chases rats, crayfish, crabs, worms, and insects. In fact, the otter eats anything it finds in the water. Otters can live up to fifteen years in captivity, but the average lifespan in the wild only comes up to about four years. Nature has found a solution for this: in areas where more otters die because of traffic or pollution, the average otter litter comprises of not two, but up to five young.

Otters are territorial animals; while searching for food, they cover an area of up to ten kilometers. Mostly at night though; at daytime, they rest in underground locations such as reed beds, but also the occasional hollow tree. After reaching maturity, young otters migrate to greener – or rather, bluer – pastures. Otters can swim up to eight hours straight, at an average speed of up to two kilometers per hour. One otter swam and walked from the province of Groningen all the way to the province of Overijssel in one month. A true feat! Unfortunately, it was then killed while crossing yet another road.

In 2011, otter excrements were found in the Veluwe. This marked the first time in 23 years that an otter lived in the region. It has also ‘invaded’ regions such as Twente, De Vecht and Flevoland. Even in the urban conglomeration, otters were spotted on camera traps. A male and female have been living in the Nieuwkoopse Plassen in South Holland since 2013. The female unfortunately died in January 2015. “It is sad,” forester Juriaan van Leeuwen said in the Leidsch Dagblad of 12 January. “Every otter that perishes, endangers the survival of the species.” Otter road kill decimates the population on a yearly basis. In 2013, no less than 32 otters were killed because of a passing car, truck or motor, society ‘Das & Boom’ and the ‘Otterstation Nederland’ announced last year. That was almost one third of the total otter population in the Netherlands.

 

At least 50 otters have to live in the Netherlands for that population to be viable. It is currently estimated that 140 otters wander throughout the country, and the ultimate aim is to have over 1,000 otters looking for food and a mate in this country in 2020. There is another problem though: inbreeding. Most of the current 140 otters stem from the same ancestors. This could have dire effects on the species; the fertility of female otters could decrease, which would lead to fewer otters to be born. Research organization Alterra therefore advises for new otters to be shipped in from abroad. These genetically non-related individuals would help improve the otter gene pool.

People living in the Netherlands are called upon to come up with new and innovative ideas for increasing the chances of survival for the otter. This so-called ‘Otter Challenge’ has brought up a variety of proposals, such as otter billboards and otter highways. Last month, the finalist ideas were announced: the realization of freshwater fish ponds and the foundation of an otter knowledge center together with an ‘Otter Express’, which visits schools to inform children about this animal. Another potentially feasible idea would be to prepare regions for the future arrival of wandering otters. A region such as the Green Delta near Den Bosch should become a “blue” Green Delta. The winning idea will be announced on March 25.

 

Of course, the main question is: do otters have a feasible chance to make the Netherlands their permanent home? They just might, but not without the help of their greatest adversaries: humans. Apart from the road kills, otters also die in certain type of (ale) fish nets. Solutions for these traps have been found already. Fish nets can be adjusted in such a way that trapped otters can get out alive. With regard to the road kills, another innovative idea has been brought up besides otter tunnels: introducing a warning signal alongside the highways. As soon as an otter or larger animal wanders near the highway, the advised maximum speed is lowered on the digital speed signs. An emergency stop at 100 kilometers per hour instead of 130 kilometers per hour could mean the difference between life and death for unsuspecting otters playing Russian roulette every time they cross another road.