[MARMAM] New paper on cetacean abundance in the Central North Atlantic

Daniel Pike kinguq at gmail.com
Mon Jun 1 16:23:19 PDT 2020


We are pleased to announce the publication of the following paper in NAMMCO
Scientific Publications:
Pike, D.G., Gunnlaugsson, T., Mikkelsen, B., Halldórsson, S.D., Víkingsson,
G.A., Acquarone, M. & Desportes, G. (2020). Estimates of the Abundance of
Cetaceans in the Central North Atlantic From the T-NASS Icelandic and
Faroese Ship Surveys Conducted in 2007. *NAMMCO Scientific Publications *11.
https://doi.org/10.7557/3.5269

*ABSTRACT*
The Trans-North Atlantic Sightings Survey (T-NASS) carried out in June-July
2007 was the fifth in a series of large-scale cetacean surveys conducted
previously in 1987, 1989, 1995 and 2001. The core survey area covered about
1.8 million nm² spanning from the Eastern Barents Sea at 34°E to the east
coast of Canada, and between 52°N and 78°N in the east and south to 42°N in
the west. We present design-based abundance estimates from the Faroese and
Icelandic vessel survey components of T-NASS, as well as results from
ancillary vessels that covered adjoining areas. The 4 dedicated survey
vessels used a Buckland-Turnock (B-T) mode with a tracker platform
searching an area ahead of the primary platform and tracking sightings to
provide data for bias correction. Both uncorrected estimates, using the
combined non-duplicate sightings from both platforms, and mark-recapture
estimates, correcting estimates from the primary platform for bias due to
perception and availability, are presented for those species with a
sufficient number of sightings. Corrected estimates for the core survey
area are as follows: fin whales (*Balaenoptera physalus*): 30,777
(CV=0.19); humpback whales (*Megaptera novaeangliae*): 18,105 (CV=0.43);
sperm whales (*Physeter macrocephalus*): 12,268 (CV=0.33); long-finned
pilot whales (*Globicephala melas*): 87,417 (CV=0.38); white-beaked
dolphins (*Lagenorhynchus albirostris*): 91,277 (CV=0.53); and white-sided
dolphins (*L. acutus*): 81,008 (CV=0.54). Uncorrected estimates only were
possible for common minke whales (*B. acutorstrata*): 12,427 (CV=0.27); and
sei whales (*B. borealis*): 5,159 (CV=0.47). Sighting rates from the
ancillary vessels, which used a single platform, were lower than those from
the dedicated vessels in areas where they overlapped. No evidence of
responsive movement by any species was detected, but there was some
indication that distance measurements by the primary platform may have been
negatively biased. The significance of this for the abundance estimates is
discussed. The relative merits of B-T over other survey modes are discussed
and recommendations for future surveys provided.

The paper is available for download here:
https://septentrio.uit.no/index.php/NAMMCOSP/article/view/5269

Best regards, Daniel Pike.
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