Mukhtar Farooqi, Virginia Department of Game and Inland Fisheries, 5806 Mooretown Road, Williamsburg, VA 23188 and Miran Aprahamian, Environmental Agency, Richard Fairclough House, Knutsford Road, Warrington WA4 1HG, United Kingdom

Abstract. The acquisition of quantitative data for juvenile salmonid stock assessment can be a time consuming and labor intensive procedure particularly when contemplating a large number of sites. The removal method of population estimation is a commonly used approach, but an alternative strategy might be to conduct a single fishing without the use of stop nets. This would enable a larger number of sites to be sampled within given time and resource constraints. For such results to be of value, it is necessary to equate the findings of this less accurate method with those that would have been obtained from a quantitative survey at the same site. The aim of this study is to determine the relationship between the two sampling techniques to assess whether the semi-quantitative technique can be used as a reliable means of stock assessment. A significant relationship was found to exist between the semi-quantitative and quantitative population estimates for 0+ and 1+ salmon (Salmo salar L.), and 0+ and >0+ brown trout (S. trutta L.). The R² ranged from 83.4% to 96.1%, p < 0.0001. Thus the semi-quantitative sampling technique can be used as an effective and rapid means of routine stock assessment of juvenile salmonids.