Abundance of harbour porpoise and other cetaceans in the North Sea and adjacent waters
Hammond, P.S.; Berggren, P.; Benke, H.; Borchers, D.L.; Collet, A.; Heide-Jørgensen, M.P.; Heimlich-Boran, S.; Hiby, A.R.; Leopold, M.F.; Øien, N. (2002). Abundance of harbour porpoise and other cetaceans in the North Sea and adjacent waters. J. Appl. Ecol. 39: 361-376 In: Journal of Applied Ecology. British Ecological Society: Oxford. ISSN 0021-8901; e-ISSN 1365-2664, more |   |
| Keywords | Conservation
Management
Surveys
Phocoena phocoena (Linnaeus, 1758) [WoRMS]
ANE, North Sea [Marine Regions]
Marine/Coastal |
| Authors | | Top | Dataset | - Hammond, P.S.
- Berggren, P.
- Benke, H.
- Borchers, D.L.
| - Collet, A.
- Heide-Jørgensen, M.P.
- Heimlich-Boran, S.
| - Hiby, A.R.
- Leopold, M.F., more
- Øien, N.
|
| Abstract | 1. The status of small cetaceans in the North Sea and adjacent waters has been of concernfor many years. Shipboard and aerial line transect surveys were conducted to provideaccurate and precise estimates of abundance as a basis for conservation strategy inEuropean waters.2. The survey, known as SCANS (Small Cetacean Abundance in the North Sea), wasconducted in summer 1994 and designed to generate precise and unbiased abundanceestimates. Thus the intensity of survey was high, and data collection and analysis methodsallowed for the probability of detection of animals on the transect line being less thanunity and, for shipboard surveys, also allowed for animal movement in response to thesurvey platform.3. Shipboard transects covered 20 000 km in an area of 890 000 km2. Aerial transectscovered 7000 km in an area of 150 000 km2.4. Three species dominated the data. Harbour porpoise Phocoena phocoena wereencountered throughout the survey area except in the Channel and the southern NorthSea. Whitebeaked dolphin Lagenorhynchus albirostris and minke whale Balaenopteraacutorostrata were found mainly in the north-western North Sea.5. Phocoena phocoena abundance for the entire survey area was estimated as 341 366[coefficient of variation (CV) = 0·14; 95% confidence interval (CI) = 260 000-449 000].The estimated number of B. acutorostrata was 8445 (CV = 0·24; 95% CI 5000-13 500).The estimate for L. albirostris based on confirmed sightings of this species was 7856(CV = 0·30; 95% CI = 4000-13 000). When Atlantic whitesided dolphin Lagenorhynchusacutus and Lagenorhynchus spp. sightings were included, this estimate increased to11 760 (CV = 0·26; 95% CI 5900-18 500).6. Shortbeaked common dolphin Delphinus delphis were found almost exclusively in theCeltic Sea. Abundance was estimated as 75 450 (CV = 0·67; 95% CI = 23 000-149 000).7. Current assessments and recommendations by international fora concerning theimpact on P. phocoena of bycatch in gillnet fisheries in the North Sea and adjacentwaters are based on these estimates. |
| Dataset | - Sea Mammal Research Unit (SMRU) SMRU Small Cetacean Abundance in the North Sea (SCANS), 1994. In: OBIS-SEAMAP . OBIS-SEAMAP, http://seamap.env.duke.edu/, 2004-05-07 10:26:49.566991-04, vector digital data., more
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