Optimal management of European eel in the Imsa River, Norway

Abstract

In the Imsa River, Norway, all upstream and downstream movement of eels has been continuously monitored since 1975. In this study the yield of the 1975 year class was calculated, and the effect on yield of various simulated management schemes, different levels of natural mortality, and different catch efficiencies for silver eels was evaluated. With high catch efficiencies for silver eels, a yellow-eel fishery will lead to a lower total yield in weight and a lower total value. With catch efficiencies for silver eels under 50%, introduction of a yellow-eel fishery will increase yield. If a yellow-eel fishery is to be introduced, age at recruitment to the fishery should be as high as possible. Yellow-eel fisheries will reduce the yield of silver eels, especially in situations with low growth rates and low natural mortality rates, whereas the yield of yellow eels will be relatively unaffected by changes in age at recruitment.

Author notes

Present address: østfold County, Environmental Administration, P.O. Box 325, N-1501 Moss, Norway.