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

Citation: Reuther, C. (1998) The Otter Habitat Network Europe (OHNE) Project Has Been Started. IUCN Otter Spec. Group Bull. 15(2): 118 - 121

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The Otter Habitat Network Europe (OHNE) Project Has Been Started

Claus Reuther

Aktion Fischotterschutz e.V., OTTER-ZENTRUM, D-29386 Hankensbüttel, Germany

Abstract: East and west of Central Europe there are thriving otter populations, but in Central Europe, populations are fragmented and isolated. THis could lead to extinction in the middle range, and the development of subspecies on either side. Project OHNE, the Otter Habitat Network for Europe, aims to reverse this by reconnecting otter populations across Central Europe. The decline is due, not to overhunting, but to habitat destruction. The project therefore concentrates on restoration of otter habitats. The only chance for the survival of the otter is a management of riverine habitats and wetlands on a large spatial base. This means that we have to develop management or utilisation strategies for the landscape which allow man to satisfy his economic and social demands as well as allow the otter to survive. The proof of concept for the project is the revitalisation of the River Ise in Lower Saxony, subject to heavy pollution, canalisation and intensive use. Since 1987, led by Aktion Fischotterschutz, approximately 500 hectares of arable land have been transformed into extensive pastureland and more than 20 kilometres of riparian woodland and hedges have been planted, the costs being borne by the Federal Ministry of Environment, the Lower Saxony Ministry of Environment, the county of Gifhorn and the donors and sponsors of Aktion Fischotterschutz. The first phase of OHNE will be the identification of areas suitable as habitat corridors for dispersal or stepping stones for reinforcing locally low populations. The second phase will use this information to induce international, national and private organisations to include these data in planning and to take initiatives for regional otter habitat network programmes.

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One of the main problems for the protection of Lutra lutra in its Central European range is the fragmentation and isolation of split populations. Whilst stable or thriving otter populations remain in the east and west, only isolated populations remain in Central Europe.

This situation contains great risks for the survival of the species:

  • The former closed distribution area, which covered the whole of Europe only 80 years ago, threatens to be split into an eastern and a western population. This leads to the risk of genetic isolation of these two populations and could finish in the development of two sub-species.
  • As the history of the decrease in the otter population shows, fragmented and isolated populations are not viable. This leads to the risk that the decrease in the otter population will continue and will result in an increasing area where the otter is extinct.

The aim of the ‘Otter Habitat Network for Europe (OHNE)’ project is to reverse this development, i.e. to re-connect the isolated populations.

The main reason for the decrease of the otter population has not been overhunting but the destruction of habitats. The canalisation of rivers, the loss of structure diversity, the destruction of riparian vegetation, the drainage of wetlands, water pollution, etc. are all results of this habitat destruction. Many of these measures are caused by the increase of industrial agriculture and forestry as well as urbanisation of the landscape.

Therefore, a re-connection of isolated otter populations has to be based upon a restoration of otter habitats. Restoration of otter habitats offers a great chance for otter conservation and the OHNE project can become a symbol for the management of wetlands according to AGENDA 21.

The otter is a species, which can demand a large living area. Each individual can claim dozens of kilometres of river or hundreds of hectares of wetland as a territory. Therefore, traditional conservation policy, which focuses on reserves (generally too small) for different species, reaches its limits. Survival of the otter exclusively on the basis of protected areas will not be successful!

The only chance for the survival of the otter is a management of riverine habitats and wetlands on a large spatial base. This means that we have to develop management or utilisation strategies for the landscape which allow man to satisfy his economic and social demands as well as allow the otter to survive - an idea clearly central to the aims of AGENDA 21.

A first test for the compatibility of these aims was realised for the catchment of the River Ise (Germany, Lower Saxony). This river system of 450 km, with a catchment of 420 square kilometres, represents the (habitat) bridge between the most eastern otter population of the federal state of Saxony Anhalt and the most eastern otter population of the federal state of Lower Saxony.

Within the last 100 years, this river system was canalised with no consideration for ecological principles and the adjacent landscape was transformed to extreme intensive agricultural utilisation. This resulted in a loss of structure and species diversity, the reduction of water and substance retention, high pollution with fertilisers and pesticides, a reduction of dynamic processes - and the extinction of the otter between 1960 and 1970.

Since 1987, Aktion Fischotterschutz has been working on the revitalisation of this river system. After a survey of 18 month a wide range of ecological and economic parameters, different scenarios were developed to forecast the future evolution of the river system. The scenarios were based upon ecological principles, with the aim of supporting the river’s natural attributes: retention, diversity, and dynamics. There were four fundamental premises accepted before realisation took place: no reconstruction of an 'historical state' of the river system, no technical recreation of the river bed, no establishment of a protected area and the involvement, on a voluntary basis, of all persons and interest groups concerned. The project has shown that it is possible to initiate a (semi-) natural development of a canalised river system by utilising its own natural dynamics and by altering the agricultural practice in the river's lowland from intensive to extensive use.

So far, approximately 500 hectares of arable land have been transformed into extensive pastureland and more than 20 kilometres of riparian woodland and hedges have been planted. In addition, more than 50 kilometres of marginal zones along rivers and roads now form a "green net" in this area. The costs for this project have reached, so far, approximately 18 million DM. The costs have been covered by the Federal Ministry of Environment, the Lower Saxony Ministry of Environment, the county of Gifhorn and the donors and sponsors of Aktion Fischotterschutz.

 The results are impressive and show more and more sustainable effects year by year. The most exciting example, regarding its economic and social effects, is the establishment of a marketing system for organic products, which resulted from co-operation between local farmers and the conservationists of Aktion Fischotterschutz. The most important ecological effect, besides results such as an increase in plant diversity or an increase in different endangered bird species of up to five times, is the return of the otter. Seven years after the start of the project, and more than 20 years after the last sign of an otter, immigrating (not released!) otters started to re-colonise the River Ise.

 The results of the river Ise project show that it is possible to re-connect isolated otter populations by habitat management. The experience gained from this project will now be used to establish an Otter Habitat Network for Europe (OHNE). In various European regions, there is a recognisable tendency for otter populations to expand into suitable habitats naturally, therefore, the likelihood of this network succeeding is estimated to be very high.

The network project is based upon three categories of activities:

  • To protect otter habitats and populations in the core areas of its European distribution, these forming the basis for natural re-colonisation. These protection measures should result in a population surplus and, hence, territorial or population pressures causing an emigration of animals.
  • To develop habitats between these core areas to a state where they can become suitable habitat for dispersing otters. These habitats can function as corridors between isolated populations.
  • To protect those otter habitats where only low otter populations now survive and to include them into this network of core areas and corridors. These under populated areas can function as stepping-stones in this network.

The final result of this program could be a complete re-colonisation of all riverine and wetland areas in Europe by the otter, however, this is a long range vision.

The first phase in a realisation of an Otter Habitat Network for Europe is to identify those areas, which can function as corridors or stepping-stones. This will be done in co-operation with those national experts and authorities who have a knowledge of regional otter distribution and habitat status. The survey will also consider whether otter protection status is adequate or whether restoration programs are necessary in those habitats.

The final result of this first phase will be a cartographic presentation which will show, in detail, the potential corridors and stepping-stones for a re-connection of the European otter populations, as well as the different levels of protection or development measures which are needed to establish an Otter Habitat Network for Europe. This information will be used for the second phase, i.e. inducing national governmental and private institutions (such as nature conservation authorities or societies, water authorities, farming and forestry associations, etc.) as well as international institutions (such as the European Union or the Council of Europe) to include these data in their own planning processes and to take initiatives for regional otter habitat network programmes.

Resúmen: El proyecto red de hábitats para nutrias Europa (OHNE) ha sido iniciado.
Uno de los principales problemas para la protección de las nutrias (Lutra lutra) en Europa central es la fragmentación y el aislamiento de sus poblaciones. El principal objetivo del proyecto OHNE es reconectar poblaciones aisladas. La principal causa del descenso en las poblaciones de nutrias es la destrucción de su hábitat, por lo que la reconección de poblaciones aisladas debe ir de la mano con iniciativas de restauración de hábitat. La única chance de supervivencia para las nutrias es el manejo a gran escala de hábitats riparios y humedales, lo que debe articularse con la satisfacción de demandas económicas y sociales. Una primera prueba de la compatibilidad entre estos objetivos fue realizada en el Río Ise en Alemania. En los últimos 100 años en este río han habido modificaciones en su cause y en las tierras adyacentes con fines productivos, provocando el deterioro de las condiciones ambientales y la extinción local de las nutrias entre las décadas de 1960 y 1970. Desde 1987 Aktion Fischotterschutz viene trabajando en la recuperación del área a través de la utilización de la propia dinámica del río y la alteración de la práctica agrícola a un uso más extensivo, sin recurrir a la recreación técnica del lecho del río, reconstrucción de sus condiciones históricas, ni al establecimiento de áreas protegidas. El ejemplo más claro de los efectos positivos desde el punto de vista social y económico de esta iniciativa, es el establecimiento de un mercado de productos orgánicos, resultado de la cooperación entre granjeros locales y conservacionistas. Desde un punto de vista ecológico el efecto es evidente por el aumento de la diversidad de especies vegetales y de aves amenazadas, y la recolonización natural del área por nutrias. Los resultados de esta experiencia demuestran que es posible reconectar poblaciones aisladas de nutrias a través del manejo de su hábitat.
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