Abundance of harbour porpoise and other cetaceans in the North Sea and adjacent waters

摘要: 1. The status of small cetaceans in the North Sea and adjacent waters has been concern for many years. Shipboard aerial line transect surveys were conducted to provide accurate precise estimates abundance as a basis conservation strategy European waters. 2. survey, known SCANS (Small Cetacean Abundance Sea), was summer 1994 designed generate unbiased estimates. Thus intensity survey high, data collection analysis methods allowed probability detection animals on being less than unity and, shipboard surveys, also animal movement response platform. 3. transects covered 20 000 km an area 890 km2. Aerial 7000 150 4. Three species dominated data. Harbour porpoise Phocoena phocoena encountered throughout except Channel southern Sea. Whitebeaked dolphin Lagenorhynchus albirostris minke whale Balaenoptera acutorostrata found mainly north-western 5. entire estimated 341 366 [coefficient variation (CV) = 0.14; 95% confidence interval (CI) 260 000-449 000]. number B. 8445 (CV 0.24; CI 5000-13 500). estimate L. based confirmed sightings this 7856 0.30; 4000-13 000). When Atlantic whitesided acutus spp. included, increased 11 760 0.26; 5900-18 6. Shortbeaked common Delphinus delphis almost exclusively Celtic 75 450 0.67; 23 000-149 7. Current assessments recommendations by international fora concerning impact P. bycatch gillnet fisheries are these