Volume 3 Pages 1 - 51 (March 1988)

Citation: Harrison, C.J.O.  (1988) The Otter Trust and the River Otter Studbook. IUCN Otter Spec. Group Bull. 3: 10 - 11

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The Otter Trust and the River Otter Studbook

Colin J.O. Harrison

Chairman, Scientific Advisory Committee, The Otter Trust, Earsham, near Bungay, Suffolk, U.K.

In his article In the IUCN Otter Specialist Group Bulletin No. 2 Dr. Klaus Robin suggested that the Chairman of the Otter Trust. Mr. Philip Wayre, had failed to co-operate in the keeping of a studbook for captive otters held in zoos. This seems to highlight a misunderstanding of the Trust's function in keeping and breeding European Otters Lutra. l. lutra.

The Trust has envisaged its function insofar as this species, and sub-species, is concerned as conservation through publicity, through the encouragement of refuge creation and through the study of the animals. Because the destruction of otter populations has resulted in numbers in many regions falling below that which will allow natural re-establishment if and when conditions improve, the Trust holds a number of breeding pairs of European Otters specifically to provide individuals for re-introduction. However, it is a conservation organisation, not a zoo, and these otters are not intended as part of a permanent captive-breeding and captive-bred population spread among zoos and necessitating the kind of studbook maintained for such circumstances.

The Trust has never disposed of any of our native otters at any time to any zoo, either in the United Kingdom or Europe, nor has it at any time received any otters from any zoo either in the United Kingdom or Europe. It does not foresee any likelihood that it will become necessary for it to do so. It works In close co-operation with the Nature Conservancy Council and qualified scientific staff are responsible for keeping accurate records both of the Trust's breeding operation and of its other conservation work including its re-introduction programme.

All the Trust's European Otters descend from animals taken from the wild in Britain, many of them before such action required a licence issued by the Nature Conservancy Council. In addition, in recent years the Trust has been fortunate In receiving under licence several orphaned otter cubs which have helped to ensure a wide range of unrelated animals for breeding purposes. Naturally in order to regulate breeding pedigrees are maintained for all otters in the Trust's collection and in order to ensure that the genetic identity is maintained the Trust has never at any time cross-bred otters of the nominate race with animals of any other sub-species. These pedigrees are in slightly different format to that used by the zoo studbook. The Trust has offered these pedigrees of all the European Otters In the Trust's collection at Earsham and at its branch at North Petherwln In Cornwall to Dr. Robin although, as indicated, they may have little relevance to the zoo studbook. Where captive otters are concerned the Trust's real contribution would seem to be the knowledge it has gained on the keeping and breeding of these animals.

As far as is known the Otter Trust is the only place in the world where the European Otter is bred regularly and in sufficient numbers to ensure an annual programme of re-introduction into the wild using young otters bred by the Trust.

The first such re-introduction took place in 1983 when one young male and two females were released on a river in East Anglia after the selected site had been subjected to a very thorough scientific investigation by scientists of the Nature Conservancy Council and of the Otter Trust to ensure that it satisfied all the criteria necessary for the otters' survival, including the whole-hearted co-operation of all the landowners on that particular river system.

The male of the first release carried a radio transmitter on a harness which was designed to disintegrate after a few weeks. In fact it disintegrated and was recovered seven weeks after the animals had been aet free. During this time almost nightly monitoring had provided a detailed record of the animals' movements and it was clear that they had become shy, secretive and nocturnal and were behaving in all respects like wild otters, including the establishment of individual territories.

Prior to their release young otters at the Trust are maintained for a period of several months in large pre-release enclosures in a private part of the Trust's grounds where they are disturbed as little as possible so that they become shy and nocturnal and are able to adapt quickly to life in the wild.

The first proof of successful breeding in the wild of released otters occurred on 14th August, 1984 when the Trust's Conservation Officer, during one of her regular checks, discovered the tracks of an otter cub following those of an adult showing clearly in the mud beneath a road bridge in the known range of one of the released females.

Three further re-introductions to the wild of young otters, totalling eight animals bred at the Trust were made in 1984 and 1983 and already one male has been released in 1987 and a young pair is destined to be set free later this summer.

Regular monitoring has shown that the released animals have bred and successfully reared cubs in the wild every year since 1984 with 1986 being a bumper year when six of the re-introduced bitches are known to have bred and to have successfully reared their cubs in the wild. The success of this project means that the released otters and their progeny must now constitute the major proportion of wild otters in East Anglia.

This re-introduction programme will be continued annually wherever suitable habitat can be found and with its newly established branch in Cornwall it is anticipated that the Trust will, before long, look for suitable re-introduction sites in southern and southwestern England.

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