TY - JOUR

T1 - Biological parameters in a declining population of narwhals (Monodon monoceros) in Scoresby Sound, Southeast Greenland

AU - Garde, Eva

AU - Tervo, Outi M.

AU - Sinding, Mikkel Holger S.

AU - Nielsen, Nynne H.

AU - Cornett, Claus

AU - Heide-Jørgensen, Mads Peter

N1 - Funding Information: We thank the hunters from Ittoqqortoormiit for providing narwhal samples for this study, A. Moos for design and construction of the scale used for weighing narwhals in the field, and K. Andersen for invaluable assistance in the laboratory. We also thank the two reviewers for their thorough and detailed reviews, which have improved the final manuscript. Import of samples into Denmark from Greenland was authorized by Convention on International Trade in Endangered Species of Wild Fauna and Flora permits IM 0721-199/08, IM 0330-819/09, and IM 0905-590/17. Funding for this study was obtained from the Greenland Institute of Natural Resources, the Carlsberg Foundation, the Northeast Greenland Environmental Study Program, and the Danish Cooperation for the Environment in the Arctic. Access and permits to use land facilities and live-tagging of the narwhals in Scoresby Sound were provided by the Government of Greenland. No protected species were sampled. Publisher Copyright: © 2022 The Author(s).

PY - 2022

Y1 - 2022

N2 - A decreasing trend in narwhal (Monodon monoceros Linnaeus, 1758) abundance has been identified in a small population in Scoresby Sound, Southeast Greenland. We hypothesize that excessive hunting has affected life history and population dynamics of this population. Biological information and samples collected from the Inuit hunt, from satellite-tagged narwhals and from official hunters’ reports, were used to estimate age, growth, and reproduction. During 2007 through 2019, a decreasing proportion of young and increasing proportion of older whales were harvested. Male and female body length and male tusk length increased significantly, while body mass of both sexes showed a nonsignificant increase. The probability of catching a female decreased significantly, while a nonsignificant decline of catching a pregnant female was observed in both biological samples and hunters’ reports. Narwhal swimming speeds correlated with fluke widths indicated that larger whales attain greater speeds. The decline in juveniles and females is probably due to an opportunistic hunting practice targeting the easiest-to-catch whales, where bigger whales are faster and more difficult to catch. The cumulative effect of overharvest with a declining proportion of females, an overrepresentation of large males, and a lack of calves and juveniles has detrimental implications for this small narwhal population.

AB - A decreasing trend in narwhal (Monodon monoceros Linnaeus, 1758) abundance has been identified in a small population in Scoresby Sound, Southeast Greenland. We hypothesize that excessive hunting has affected life history and population dynamics of this population. Biological information and samples collected from the Inuit hunt, from satellite-tagged narwhals and from official hunters’ reports, were used to estimate age, growth, and reproduction. During 2007 through 2019, a decreasing proportion of young and increasing proportion of older whales were harvested. Male and female body length and male tusk length increased significantly, while body mass of both sexes showed a nonsignificant increase. The probability of catching a female decreased significantly, while a nonsignificant decline of catching a pregnant female was observed in both biological samples and hunters’ reports. Narwhal swimming speeds correlated with fluke widths indicated that larger whales attain greater speeds. The decline in juveniles and females is probably due to an opportunistic hunting practice targeting the easiest-to-catch whales, where bigger whales are faster and more difficult to catch. The cumulative effect of overharvest with a declining proportion of females, an overrepresentation of large males, and a lack of calves and juveniles has detrimental implications for this small narwhal population.

KW - Arctic

KW - Harvest

KW - Life history

KW - Marine mammal

KW - Monodon monoceros

U2 - 10.1139/as-2021-0009

DO - 10.1139/as-2021-0009

M3 - Journal article

AN - SCOPUS:85131065151

VL - 8

SP - 329

EP - 348

JO - Arctic Science

JF - Arctic Science

SN - 2368-7460

IS - 2

ER -