Distribution and abundance of large whales in Norwegian and adjacent waters based on ship surveys 1995-2001
DOI:
https://doi.org/10.7557/3.2704Keywords:
distribution, abundance, whales, North Atlantic, surveysAbstract
The abundances of large whale species are presented for the northeast Atlantic from near-complete survey coverage in 1995 and from multiple partial-area surveys during 1996-2001. These Norwegian shipboard surveys were generally conducted with 2 independent observer platforms, except for single-platform surveys during part of 1995. Tracking procedures implemented for minke whales – Balaenoptera acutorostrata (the target species) meant that the surveys had to be conducted in passing mode, and there were therefore only limited opportunities for closing on sightings to determine species identity and school size. Abundance estimates for large whale species (fin – Balaenoptera physalus, humpback – Megaptera novaeangliae and sperm whales – Physeter macrocephalus) were obtained by combining sightings from both platforms, and applying standard distance sampling techniques to the smeared and truncated perpendicular distances for each species. Abundance estimates for the 2 survey groupings (1995 and 1996-2001) summarised over comparable areas were: fin whales, 5,034 (cv 0.209) and 6,409 (cv 0.18); humpback whales, 1,059 (cv 0.248) and 1,450 (cv 0.29); and sperm whales, 4,319 (cv 0.199) and 6,207 (cv 0.22). The estimated cv’s are likely underestimates and specifically the combined partial-area survey cv’s do not include additional variance due to possible distributional shifts between years. Inclusion of a new survey stratum north of Iceland (block NVS) in the later set of surveys revealed a high additional abundance there of fin whales 3,960 (cv 0.538) and humpback whales 3,246 (cv 0.512). The high humpback whale estimate for this stratum confirms the Icelandic survey findings of a large humpback whale population summering in that area.Downloads
Published
2009-09-01
How to Cite
Øien, N. (2009). Distribution and abundance of large whales in Norwegian and adjacent waters based on ship surveys 1995-2001. NAMMCO Scientific Publications, 7, 31–47. https://doi.org/10.7557/3.2704
Issue
Section
Articles
License
Authors who publish with this journal agree to the following terms:
- Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.
- Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.
- Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work (See The Effect of Open Access).