THE EFFECTS OF FIXED SALMON SALMO-SALAR NETS ON GUILLEMOT URIA-AALGE AND RAZORBILL ALCA-TORDA IN NORTHEAST SCOTLAND IN 1992

Guillemots Uria aalge and razorbills Alca torda were the main seabird species killed in salmon Salmo salar bag nets in northeast Scotland in 1992, with guillemots outnumbering razorbills two- to three-fold. Sexually immature birds were more likely to become entangled compared with breeding adults, probably because they spend more time on the sea close inshore or have not learned to avoid nets. The total number of auks drowned in northeast Scotland in 1992 was estimated to be around 2400 (1700 guillemots, 700 razorbills). While these deaths are obviously to be regretted, our preliminary estimates suggested that losses were relatively small in relation to the total number of auks present in the area. Losses of breeding birds were estimated to represent <0.5% of the breeding population of the two species and c. 0.6% of sexually immature guillemots. Similar calculations for a stretch of coastline where conflict between seabirds and the fishery is considered to be potentially serious indicated that c. 1.2% of breeding auks and 6.0% of sexually immature guillemots were drowned. The latter figure was almost certainly an overestimate because no allowance was made for immatures from other colonies being present in the area. The Scottish salmon fixed net fishery has declined greatly in recent years and its impact on marine birds is therefore likely to be reduced. Any revival in the fishery or change of practice should be accompanied by an assessment of its effect on seabirds.