A review of plaice (Pleuronectes platessa) transplantation trials in Denmark 1891-1990

Transplantation of young plaice (Pleuronectes platessa) in Denmark started back in the last century. The first published data are from 1891. Experiments were initiated by local fishermen and sponsored by the government. Large quantities of small plaice (16-19 cm) were caught, either in the western part of the estuarine fjord Limfjorden close to the North Sea or in the coastal waters of the North Sea, and transplanted to the inner parts of the fjord and to water bodies between the Danish islands in the southern Kattegat. In a few cases, transplantations of plaice to the central North Sea (Dogger Bank) were also carried out. The idea was to enhance either the local stocks or just the catch. The latter was the case for the Limfjord area, where the great majority of the transplantations were carried out. The work started in 1891 and continued for more than sixty years, during which time about 60001 were transplanted. The work stopped in 1958 due to the lack of financial support from the government. Up to then the transplantations had been the topic of long economic and political discussion. The overall conclusion concerning the economics of the matter was that no net gain was actually being obtained by the transplantations except in certain areas in Limfjord. In 1984, some minor experiments initiated by the Fishermen’s Association were again started up in Limfjord. The findings of this work were that the plaice stayed in the fjord and that the growth rate was satisfactory. In 1988, a semi-commercial transplantation programme was initiated and 14000 plaice were transplanted to Limfjord. In 1989, the programme was expanded, 132000 being transplanted to Limfjord and 30000 to other water bodies in Denmark. This new work also included turbot (Scopthalmus maximus), eels (Anguilla anguilla), whitefish (Coreogonus sp.), rainbow trout (Salmo gairdneri), reared in captivity, and cod (Gadus morhua), caught in the wild. The government is granting this new work Dkr 1 mill, in 1990. The final question is, of course, whether or not such transplantations of plaice and other marine species should be carried out. The conclusions have to be drawn on both an economic and ecological basis. The present paper summarizes experiences from transplantation programmes and attempts to provide suggestions for the future work.

This article is part of Marine Science Symposia Volume 192 - "The ecology and management aspects of extensive mariculture". To access other articles from this volume, please use the link to the volume on the upper right hand side.