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Volume 15 Issue 2 Pages 68 - 127 (October 1998)

Citation: Jongh, AWJJ de (1998) Re-Introduction Of Otters - Support Or Risk For Otter Conservation? IUCN Otter Spec. Group Bull. 15(2): 80 - 86

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Re-Introduction Of Otters - Support Or Risk For Otter Conservation?

Addy W.J.J. de Jongh 1

1Dutch Otterstation Foundation, De Groene Ster 2, 8926 XE Leeuwarden, The Netherlands

Abstract: Otters decreased in numbers during the last through decades in many parts of Europe, with populations fragmenting or being extirpated, but this has been lately reversed through wetland improvement and so on. Before re-stocking or re-introducing otters, one has to be sure that the conditions for survival are adequate and that all the original causes for the decline or extinction of the population have been removed. All of the IUCN Guidelines for Re-introductions have to be followed.In many cases, releasing otters is not necessary at all as a natural influx of animals from neighbouring populations will soon follow after the former threats have been removed.In other areas, such as Holland, this could take more than 50 years because the nearest flourishing populations are so far away. Re-introductions help to establish more populations throughout Europe, securing the long-term survival of the entire population. Well-prepared and performed re-introductions give more impact to the otter’s function as a symbol. Re-introductions contribute to a higher bio-diversity. Re-introductions, and even preparations in that direction, provide economic benefits with respect to employment, cash flow and also environmental awareness. Under suitable restrictions, such as those already mentioned, I am in favour of re-introductions and, in some areas, restocking.


The Dutch have been famous for re-conquering land from the sea, not only in their own country but also in many other parts of the world. People say that God created the world and the Dutch created Holland 50 years later. In other words, when discussing nature and re-introductions, it should be remembered that much of what we consider ‘natural’ is not as natural as we would like to think. The same is true for many wetlands. Nevertheless, in these areas one can find high natural values, reflected in an impressive level of biodiversity. In many of these wetlands, otters are present as the top predator. It has been generally accepted that the status (or presence) of an otter population in such wetlands could show the ‘health’ of such an ecosystem.

Over recent decades, otter populations have decreased in numbers in many parts of Europe. Populations became fragmented or became extinct due to the destruction of their habitat and human exploitation of natural resources. In some cases, the latter factor has been more detrimental (e.g. drowning in fyke nets).

We can be very happy now that the tide has started to turn. In several European countries, where populations were once threatened, otters are now increasing in numbers and gradually expanding their range. This appears to have come about through a general improvement in wetland quality, the easing of barriers between populations, re-introduction or re-stocking efforts and/or measures that have been taken to prevent otters from drowning in fyke nets.

Although this is a positive sign, we must realise that the economic development of central and east European countries still poses a threat to the surviving otter populations in these countries. Therefore, the International Union for the Conservation of Nature (IUCN) Otter Specialist Group has made it a top priority to promote and support the conservation of these otter strongholds.

It is, however, equally important to restore former otter habitats. Our goal must be to create a network of wetlands throughout Europe as a whole, in which otters can survive in almost any part of Europe (Reuther, 1994). The European Community has accepted this concept, not only for wetlands but also for other ecosystems. In the Netherlands this idea has already been put into practice, where it has been called the Ecological Head Structure (EHS). Within this econet, agricultural land is bought and turned into new wetlands, fitting within the existing landscape. In some cases, old meanders of rivers and brooks are restored. In fact, existing nature is being preserved or restored and new nature is being built. In certain areas, Mother Nature takes over control after the reconstruction, in other area’s this is the job of people. There are areas where the natural succession from open water to swampy forests is stopped and maintained at the desired stage to obtain the biodiversity aimed for. This is a matter of human choice, a matter of management.

Unfortunately, nowadays, nature management has to go hand in hand with technical support and devices, especially in countries with dense human populations (de Jongh, 1995). Tunnels or ‘ecoducts’ will have to be built under roads to ensure safe passage for all kinds of wildlife, including the otter. It is too idealistic to believe that the building of more and more roads in Europe can be stopped, I am afraid there will be many more though, of course, the struggle must go on to prevent highways or other human structures being built inside wetlands. We must make sure that it becomes standard policy to build tunnels and other devices under all railways and roads. Along rivers and canals with a lot of traffic, measures have to be taken in many cases to prevent bank erosion. In all cases, these problems can be solved with the aid of nature itself, in the latter case, for example, through the use of reed beds. Villages, towns and cities are all destined to grow, and in such a way that they may block some important migration bottlenecks. However, there are ways of spatial planning that allow an integration of natural structures into urban areas.

Sense or nonsense of re-introduction

Before even thinking about re-stocking or re-introducing otters, one has to be sure that the conditions for survival are adequate and that all the original causes for the decline or extinction of the population have been removed. All of the IUCN Guidelines for Re-introductions have to be followed. If these are not obeyed, there are high risks that the re-introduction will fail. A re-introduction that fails could mean an enormous negative blow for the conservation of the species. In many cases, releasing otters is not necessary at all as a natural influx of animals from neighbouring populations will soon follow after the former threats have been removed. This is definitely true when there are no barriers in the landscape and when existing populations are not that far away.

In the Netherlands, there were many problems about the plan to release white tailed eagles along the big rivers. Because of weak and badly prepared publicity, many people were given the impression, wrongly, that along these rivers, everything was once again fine. However, during discussions, it appeared that the breeding cases of this magnificent bird were shifting towards the Netherlands by itself. The release of this raptor species was therefore cancelled and it is expected that the bird will breed in the Netherlands within the next decade.

  • Birds can fly, but otters don’t. Therefore, what about those areas that are very remote from the present flourishing populations or the area’s that are isolated from those populations? Why should we wait maybe more than 50 years or even more than a century (and sometimes never) to let the otter return by itself? When it is really possible, why not start a re-introduction? 
  • Under suitable restrictions, such as those already mentioned (IUCN, 1998), I am in favour of re-introductions and, in some areas, restocking. I admit right away that in many cases it is all to do with ecological impatience. Why wait so long? I believe re-introduction is a tool that can be very beneficial in terms of 1) re-establishing a keystone species and therefore enhancing biodiversity, of 2) the promotion of conservation awareness and 3) economics.

I am sure that the concept of an approaching re-introduction of otters in, for example, the Netherlands, has given an enormous drive to preserve, restore, and build otter habitats. Should that concept not have been there the results would not have been so spectacular. That has nothing to do with our promotion and education being bad; this has been done in a sound way. The return of the otter by re-introduction has not been presented as the reward, but is seen as an extra stimulus. However, what if it should be a reward! As long as it is a reward with the right content of ecology and sustainability behind it, it isn’t so bad. The work towards a re-introduction itself is a good concrete tool that helps people understand that which is necessary to get a species back that was once extinct. No steps should be forgotten in the accompanying educational process of course! When we Europeans are maybe one or two generations ahead, such a tool or other tools should no longer be necessary. It is too idealistic to say that we already understand the process now or that we can explain it to its fullest extent to everybody. Unfortunately, ordinary people are not yet that far in their understanding. Not everybody comes to educational centres, like the otter stations in Hankensbüttel or Leeuwarden, to get a good stroke of this. Therefore, vehicles are needed for this, suitable for these times. In the meantime, we have no time left to wait for other generations to grow up, we have to act now and make use of the available tools in an appropriate way.

If promotion and education measures have been undertaken correctly, no politician, civil servant or contractor should come to you for compensation offers or a bribe as they understand that they will fail in the public view by asking for these. Well-prepared re-introductions will not weaken the position of otter (habitat) protection. On the contrary, due to their great media impact they will strengthen it, when put in the right perspective, i.e. they are made possible only by good habitat protection and management.

  •  Good re-introductions are costly. Why not use this money for protection of otters and otter habitat in the vulnerable area’s of Europe? There is no discussion about the fact that much of money is indeed needed for research and habitat protection in those areas. However, when we really look at the sources of the money spent on re-introductions it appears that in many cases these (mostly local) funds would not have been granted for the other necessary work in the central and east European countries. In setting up proposals for re-introductions, there are however, chances to involve the research work abroad.

Although it seems that there are plenty of otters in east Europe, there are several signs that these vast populations are not safe. To preserve the otter on a European scale we should not only protect these populations and their habitats, but we should also enable the establishment of populations elsewhere. Re-introduction (according to the guidelines!) helps establish populations in a faster way than would occur through natural migration. These re-introduced populations may prove to be important if, for whatever reason, the populations in the east should decline.

When aiming towards connection of all otter populations in the whole of Europe it is much better to have more otter populations throughout Europe than just hoping for natural migration from the east going west, north and south. This is not only common sense but can be supported with models based on population dynamics.

There is also an economic value to the re-introduction of the otter. During the last two decades the animal gained a lot of popularity due to its nice looks, playful behaviour and last, but not least, its role as an ambassador of wetlands. The hoped for presence of this animal alone has shown to have an important economic value already in several countries. Restoring and making new otter habitat yields employment and cash flow. It has also led to acceptable forms of local eco-tourism. Fishermen in the north of the Netherlands no longer look at the otter as an enemy (for central European countries with many fishponds this is probably a utopian dream). When there are otters their fish must be of good quality. There could come a time when they will sell their fish with an otter trademark! There is also an important gut feeling that, after the re-introduction the area will have more value, because its ambassador is back.

I therefore believe that, under certain circumstances, re-introductions of otters in Europe do meet the objectives of the IUCN guidelines:

  1. Re-introductions help to establish more (sub-) populations throughout Europe. This will help to secure the long-term survival of the entire population.
  2. Well-prepared and performed re-introductions give more impact to the otter’s function as a symbol. We can find proof of this in several European countries.
  3. Re-introductions contribute to a higher bio-diversity. They result in one extra species in the target area. The return of any species that was lost, intrinsically means an enormous gain for nature.
  4. Re-introductions, and even preparations in that direction, provide economic benefits with respect to employment, cash flow and also environmental awareness.

 In the end, it is a matter of human belief and choice whether to wait for the otter to come back by itself or to start a re-introduction according to the guidelines. Countries that are close to good otter populations can decide more easily to wait, because they probably do not have to wait that long anymore for the return of the otter. It is easy for those countries to tell the others to wait too.

  •  It should be considered that the extinction of otters in the areas where they are no longer present, was not a natural process. It was a process caused by man. When man has the possibility to facilitate the return of the otter, it is his duty to go on with that. Re-introduction is not a natural process, but can help. The return of the otter by itself is not a natural process either; it is also initiated by human influence through environmental recovery, building of new nature and technical measures. So, why not re-introduce?

We should be much more concerned about the way some re-introductions are planned (or not planned at all!) and performed. There are some initiatives already present and, besides that, some new re-introduction projects still come up, that do not or only partly consider the guidelines of the IUCN. These projects should be criticised and tackled when the initiators refuse to adapt the way they want to perform their re-introductions. The well-organised re-introductions, however, should not suffer from the bad ones.

At the last meeting of the IUCN Otter Specialist Group in the Czech Republic (1998), a very good solution was suggested to deal with this problem. A new committee was formed, the Re-introduction Advisory Committee (RAC). The present (elected) members of the RAC are Arno Gutleb, Jordi Ruiz Olmo, Hans Kruuk, Alfred Melissen (studbook keeper), Claus Reuther, and myself. The RAC is supposed to judge every initiative towards re-introduction of otters in Europe. The resulting advice of the committee will be given to the government agency responsible for the release of permits for the intended re-introduction. Since the RAC has an official status within the IUCN the release of permits can be cancelled or postponed in the case of a badly prepared or performed re-introduction.


IUCN (1998). IUCN Guidelines for Re-introductions. IUCN/SSC Re-introduction Specialist Group. IUCN, Gland, 20 pp.
Jongh de, A.W.J.J. (1995). In het Spoor van de Otter. Otterpark AQUALUTRA, Leeuwarden, 120 pp.
Reuther, C. (1994). European Otter Habitat Network (discussion paper). In: Report of the Otter Seminar (Council of Europe, Ministerie van Landbouw, Natuurbeheer en Visserij, IUCN Otter Specialist Group, Otterpark AQUALUTRA), Leeuwarden, pp. 188-193.

Resúmen: Reintroducción de nutrias: ¿contribución o riesgo para la conservación de las nutrias?
Cuando se discute sobre naturaleza y reintroducciones debería tomarse en cuenta que mucho de lo que consideramos natural no lo es tanto como nos gustaría. A pesar de eso en esas áreas uno pude encontrar grandes valores naturales, lo que se refleja en un impresionante nivel de biodiversidad. En varios de esos humedales las nutrias están presentes como el predador top. Se ha aceptado generalmente que el estado (o la presencia) de una población en tales humedales podría reflejar la “salud” del ecosistema. En las últimas décadas las poblaciones de nutrias han disminuido en números en varias partes de Europa. Las poblaciones se vuelven fragmentadas o se extinguen localmente debido a actividades humanas. Podemos estar contentos de que las cosas están cambiando y de que en varios países Europeos donde las poblaciones estaban amenazadas, las nutrias se están recuperando. Esto parece deberse a una mejoría en la calidad de los humedales, la remoción de barreras entre poblaciones y esfuerzos de reintroducción, reposición y para evitar que se ahogaran en redes. A pesar de estos signos positivos, debemos reconocer que el desarrollo de los países de Europa central y oriental continúa implicando amenazas para la supervivencia de las nutrias en esos países. Por eso para el IUCN OSG es una prioridad promover y apoyar la conservación de esas “fortalezas”. Es, sin embargo, igualmente importante restaurar antiguos hábitats de nutrias. Nuestro objetivo debe ser  crear una red de humedales a través de Europa. La Comunidad Europea ha aceptado este concepto tanto para humedales como para otros ecosistemas. En Holanda esta idea ya ha sido puesta en práctica, y tierra agrícola está siendo transformada en humedales, y antiguos meandros de ríos y arroyos son restaurados. De hecho, la naturaleza existente está siendo preservada o restaurada, y nueva naturaleza está siendo construida. En ciertas áreas la Madre Naturaleza toma el control tras la reconstrucción, en otras, este es trabajo de la gente. Desafortunadamente, el manejo de la naturaleza tiene que ir (actualmente) de la mano con apoyo técnico y dispositivos. Especialmente en países con poblaciones humanas densas. Túneles o “ecoductos” deberán construirse bajo las carreteras para permitir el pasaje seguro de todo tipo de vida silvestre. Es demasiado idealista creer que la construcción de rutas en Europa puede detenerse. La lucha debe dirigirse a prevenir la construcción de autopistas y otras construcciones humanas dentro de los humedales. Debemos asegurarnos que sea una política standard construir túneles y otros dispositivos bajo las vías férreas y las rutas. A lo largo de canales con mucho tráfico se deben tomar, en muchos casos, medidas para evitar la erosión de las orillas. Villas, pueblos y ciudades están destinados a crecer y de esa forma pueden bloquear importantes cuellos de botellas para migraciones. Sin embargo, existen formas de planificación del espacio que pueden permitir la integración de estructuras naturales en áreas urbanas. Antes de pensar sobre reintroducciones o reposiciones de nutrias, hay que asegurarse de que las condiciones para su supervivencia son adecuadas y las causas originales de la declinación o extinción de la población han sido eliminadas. Todos los lineamientos de la IUCN para reintroducciones deben seguirse, de lo contrario se corre el riesgo de fracasar. En muchos casos no es necesario liberar nutrias ya que el influjo natural desde poblaciones vecinas seguirá una vez eliminadas las antiguas amenazas. Esto es definitivamente cierto cuando no existen barreras en el paisaje y las poblaciones existentes no están alejadas. ¿Qué pasa con las áreas que están demasiado alejadas de las poblaciones florecientes (prósperas), o las que están aisladas de esas poblaciones? . ¿Por qué esperar más de 50 o 100 años (o por siempre) para dejar que las nutrias vuelvan por sí mismas?. Cuando es posible, ¿por qué no comenzar un reintroducción?. Bajo restricciones apropiadas (como las que señalan los lineamientos de la IUCN), estoy a favor de las reintroducciones y, en algunas áreas, la reposición de nutrias. Creo que la reintroducción puede ser muy beneficiosa en términos 1) de restablecimiento de una especie clave (y entonces de aumento de la biodiversidad), 2) de promoción de conciencia por la conservación y 3) económicos. Estoy seguro de que la idea de una próxima reintroducción de nutrias en Holanda ha dado un enorme impulso a la preservación, restauración y construcción de hábitats para nutrias. Sin esa idea los resultados no hubieran sido tan espectaculares. Esto no tiene nada que ver con una mala promoción o educación. La reintroducción de nutrias no ha sido presentado como una recompensa, es un estimulo extra. Pero ¿qué si debe usarse como recompensa?. En la medida en que sea una recompensa con el contenido apropiado de ecología y sustentabilidad, no es malo. El trabajo hacia la reintroducción es una buena herramienta concreta que ayuda a la gente a entender lo que es necesario para traer nuevamente una especie una vez extinguida. Es demasiado idealista decir que los europeos ya entendemos el proceso o que podemos explicarlo en su máxima expresión a todos. El común de la gente no llega tan lejos en su entendimiento. No todo el mundo va a centros educacionales para tener una buen idea de esto. Mientras tanto, no tenemos tiempo que perder esperando a que otras generaciones crezcan. Debemos actuar ahora haciendo correcto uso de las herramientas disponibles. Si se han llevado a cabo correctamente medidas de promoción y educación, ningún político o contratista vendrá pidiendo compensación o soborno ya que entenderán que van a perder ante la opinión pública. Reintroducciones bien preparadas no debilitarán la posición de protección de las nutrias (y sus hábitats). Por el contrario, debido a su gran impacto en los medios, la fortalecerán. Las buenas reintroducciones son costosas. ¿Por qué no usar ese dinero para la protección de las nutrias y sus hábitats en las áreas vulnerables de Europa?. Cuando se miran las fuentes de dinero para realizar reintroducciones aparece que, en muchos casos, estos fondos (mayormente locales) no hubieran sido asignados para otros trabajos necesarios. Al establecer propuestas de reintroducción hay, sin embargo, chances de involucrar el trabajo de investigación fuera del país. Aunque parece que viven muchas nutrias en Europa oriental, existen varios signos de que estas vastas poblaciones no están a salvo. Para preservar a las nutrias en una escala europea, no sólo debemos proteger esas nutrias y sus hábitats, también debemos permitir el establecimiento de poblaciones en otros lados. Las reintroducciones (según los lineamientos) ayudan a establecer poblaciones más rápidamente de lo que ocurriría por migración natural. Estas poblaciones reintroducidas pueden ser importantes si, por alguna razón, declinan las poblaciones del Este. Al apuntar hacia la conexión de todas las poblaciones de nutrias en toda Europa, es mejor tener más poblaciones a través de Europa que sólo esperar por migraciones desde el Este hacia el Oeste, el Sur y el Norte. Esto no sólo es sentido común, sino que puede ser respaldado por modelos basados en dinámicas de poblaciones. También existe un valor económico en la reintroducción de nutrias. En las últimas 2 décadas estos animales han ganado mucha popularidad. Restaurar y crear nuevos hábitats para nutrias produce flujos de empleo y divisas, y ha llevado a formas aceptables de ecoturismo. Los pescadores en el Norte de Holanda ya no ven a las nutrias como enemigo (lo que probablemente es un sueño utópico en algunos países de Europa central y oriental). Donde existen nutrias, los peces deben ser de buena calidad. Existe una sensación de que tras la reintroducción el área tendrá más valor porque su embajador ha vuelto. Creo que bajo ciertas circunstancias, las reintroducciones de nutrias en Europa alcanzan los objetivos de los lineamientos de la IUCN: 1) ayudan a establecer más (sub) poblaciones a lo largo de Europa, ayudando a asegurar la supervivencia a largo plazo de toda la población, 2) bien preparadas y ejecutadas dan más impacto a la función de las nutrias como símbolo, 3) contribuyen a una mayor biodiversidad (el regreso de una especie perdida intrínsecamente significa una enorme ganancia para la naturaleza) y 4) incluso preparativos en esa dirección proveen beneficios económicos y conciencia ambiental. Es un asunto de decisión humana esperar el regreso de las nutrias por sus medios o comenzar reintroducciones de acuerdo a los lineamientos de la IUCN. Los países que están más cerca de buenas poblaciones pueden decidir más fácilmente esperar el regreso de las nutrias porque probablemente no tendrán que hacerlo por mucho tiempo. Es fácil para esos países decirle a los otros que también esperen. Debe tenerse en cuenta que la extinción local de las nutrias no fue un proceso natural. Cuando el hombre tiene la posibilidad de facilitar el regreso de las nutrias, es su tarea hacerlo. El regreso de las nutrias por ellas mismas tampoco es un proceso natural, también es iniciado por el hombre a través de recuperación ambiental, construcción de nueva naturaleza y medidas técnicas. Entonces, ¿por qué no reintroducir?. Deberíamos estar mucho más preocupados por la manera en que algunas reintroducciones son planificadas y ejecutadas. Los malos proyectos deben ser criticados y evitados cuando quienes los proponen se niegan a modificarlos. Las reintroducciones bien planificadas no deberían sufrir por aquellas. En el último encuentro del IUCN OSG en República Checa (1998), una muy buena solución fue sugerida para tratar con este problema. Se creo el “Comité Asesor en Reintroducciones” (RAC), cuya función es evaluar todos los proyectos de reintroducción en Europa. Sus sugerencias serán entregadas a las agencias gubernamentales responsables de extender los permisos para realizar reintroducciones. Como el RAC tiene status oficial dentro de la IUCN, la extensión de estos permisos pude ser cancelada o pospuesta en reintroducciones mal planificadas o ejecutadas.
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