[MARMAM] New paper on North Atlantic killer whales
We are pleased to announce the publication of our paper: Pike, D. G., Gunnlaugsson, T., Mikkelsen, B., Víkingsson, G., & Desportes, G. (2020). Distribution and Abundance of Killer Whales in the Central North Atlantic, 1987-2015. *NAMMCO Scientific Publications*, *11*. https://doi.org/10.7557/3.5579 ABSTRACT: The North Atlantic Sightings Surveys (NASS), covering a large but variable portion of the Central and Eastern North Atlantic, were conducted in 1987, 1989, 1995, 2001, 2007 and 2015. Sightings of killer whales (Orcinus orca), a non-target species, were relatively rare in the Central Atlantic (Icelandic and Faroese) portions of the survey area. In cases where sighting numbers were insufficient, we pooled sightings over several surveys to derive a distance detection function and used this to estimate abundance using standard Distance Sampling methodology. Uncorrected estimates were produced for all surveys, and estimates corrected for perception bias were produced for the 2001 and 2015 surveys. Killer whales were sighted in all areas but were most common in the eastern part of the survey area. Uncorrected abundance in the NASS core area ranged from a low of 4,736 (95% CI: 1,842–12,176) in 1995 to a maximum of 15,142 (95% CI: 6,003–38,190) in 2001. The low precision of the estimates makes the detection of temporal trends unlikely. In 2007 an extension survey revealed relatively high numbers of killer whales to the east of the survey area, in conformity with Norwegian survey estimates in this area. The NASS and other surveys conducted over the period indicate that killer whales number in the low tens of thousands in the Central and Eastern North Atlantic. Regards, Daniel Pike. ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
[MARMAM] New paper on North Atlantic killer whales
Dear colleagues, The following paper has recently appeared in the journal Aquatic Biology: Deecke, V. B., Nykänen, M., Foote, A. D. Janik, V. M. 2011. Vocal behaviour and feeding ecology of killer whales (Orcinus orca) around Shetland, UK. Aquatic Biology, 13, 79–88. ABSTRACT: Killer whales Orcinus orca are sighted regularly off Shetland, UK, but little is known about their numbers, diet and population identity. We aimed to relate vocal behaviour to diet of killer whales around Shetland in order to investigate population structure and differences in feeding strategies. Fieldwork was conducted in the summers of 2008 and 2009. We located killer whales through a sightings network and shore-based scans and collected photo-ID data, behavioural information, feeding data and acoustic recordings from a small boat. The majority of encounters (n = 14) were of small groups (1 to 15 individuals) travelling close to shore and feeding on marine mammals. Two encounters were with large groups (20+ individuals) feeding on herring Clupea harengus farther offshore. Seal-hunting groups vocalised rarely, producing pulsed calls, echolocation clicks and whistles almost exclusively when surface-active or milling after a kill. Herring-eating groups were largely silent during one encounter, but very vocal during the other. Analysis of pulsed calls identified 6 stereotyped call types for seal-hunting groups and 7 for herring-eating groups. No call types were shared between both kinds of groups. The vocal behaviour of seal-hunting groups showed striking parallels to that of Pacific marine mammal specialists and presumably evolved to decrease detection by acoustically sensitive prey. One call type produced by Shetland herring-eating killer whales matched a vocalisation that a previous study had described from Iceland and identified as a possible herding call that may function to concentrate herring during feeding. These findings point to behavioural and dietary specialisation among Shetland killer whales, which should be taken into account when making management decisions affecting these animals. KEYWORDS: Dietary specialisation, Vocal behaviour, Feeding ecology, Killer whale, North Atlantic Please contact me v...@st-andrews.ac.ukmailto:v...@st-andrews.ac.uk with any questions about this research. All the best Volker Dr. Volker Deecke Sea Mammal Research Unit Scottish Oceans Institute University of St. Andrews St. Andrews, Fife, KY16 8LB Scotland UK Phone +44.1334.463459 Fax +44.1334.463443 The University of St Andrews is a charity registered in Scotland: No SC013532 ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
