An assessment of the potential for the application of two simple models toAtlantic salmon, Salmo salar, stock management in chalk rivers

Many salmon populations in the UK are under threat, which is assumed to res ult from a combination of anthropogenic and natural factors. Positive manag ement is required to bring them back to their former productivity levels. A n attempt has been made to use two simple models to assess the suitability of several management approaches for use on chalk rivers. One model is base d on the survival rates at each stage of the salmon life cycle and the othe r estimates the predation of young salmon by other fish. This work highligh ts the paucity of data available to calibrate even the simplest salmon mana gement models. For those variables where data are available, the variabilit y is very high. Despite the poor quality of input data, the outputs are clo se to observed numbers in the River Frome, a chalk river in Dorset, UK. The models were used to assess the effect of managing the fishery using reduce d rod catches, pike culling, gravel cleaning and trout stocking on adult sa lmon and smolt numbers.