Small Cetaceans in the European Atlantic and North Sea (SCANS) I 1994
Description
SCANS (Small Cetacean Abundance in the North Sea), was conducted in summer 1994 and designed to generate precise and unbiased abundance estimates of small cetacean species in the North Sea and adjacent waters, particularly the harbour porpoise (Phocoena phocoena).
The objectives were to identify concentrations of P. phocoena and other small cetaceans in this area and to estimate their abundance in order to provide essential information for conservation, management and future monitoring.
The project involved an intensive shipboard and aerial survey using line transect sampling (Hiby & Hammond 1989; Buckland et al. 1993). Phocoena phocoena is a difficult species for such surveys because its small size and undemonstrative behaviour at the surface make it hard to detect except in good conditions. Because of this and the aim of obtaining precise abundance estimates, the survey intensity was greater than is typical.
In addition, the aim of obtaining accurate estimates of abundance dictated that important potential sources of bias in methodology needed to be addressed. This particularly applied to estimation of the probability of detecting animals on the transect line and the possibility that animals might respond to the survey ships. The development of methods for shipboard and aerial line transect surveys specifically tailored to the estimation of absolute abundance of P. phocoena, as well as being appropriate for other species, thus formed an part of the project.
Shipboard transects covered 20 000 km in an area of 890 000 km2. Aerial transects covered 7000 km in an area of 150 000 km2.
Survey methods are detailed in Hammond et al 2002 -
https://besjournals.onlinelibrary.wiley.com/doi/full/10.1046/j.1365-2664.2002.00713.x
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https://www.ices.dk/data/data-portals/Pages/Cetaceans.aspx |
Tags
- joint-cetacean-data-programme
- cetacean
- scans