Biological data and Inuit hunter records reveal decrease of females and young in a declining narwhal population in southeast Greenland
A small population of narwhals in Scoresby Sound, Southeast Greenland, shows population decline probably caused by excessive hunting. The proportion of females and young of hunted whales has decreased during the past 13 years as revealed by data from biological samples and Inuit hunters’ own records. The population, which is subject to exploitation under quota regulations, cannot, according to the North Atlantic Marine Mammal Commission, sustain any levels of catches, and this is why a moratorium was recommended in 2019. Despite this recommendation, the quota for 2020, 2021, and 2022 was set to 40, 25, and 20 whales, respectively, jeopardizing the long-term existence of this isolated population and the prospects of continued harvest of narwhals in the local communities.
Read this open access paper on the Arctic Science website.
During a period from 2007 through 2019, we collected biological samples from the Inuit hunt and information from satellite-tagged narwhals from a field camp in the Scoresby Sound fjord. These data along with information on hunted narwhals from the official hunter reports were used to estimate age, growth, reproduction, and the proportion of females and pregnant females in the catches. Data showed a decreasing proportion of young and increasing proportion of older whales during the period. Female and male body length and male tusk length increased significantly. The probability of catching a female decreased significantly while the probability of catching a pregnant female showed a non-significant decrease.
To explain this trend, narwhal swimming speeds from satellite transmitters were correlated with fluke widths, which indicated that larger whales attain greater speeds. The decrease in young 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 decreasing proportion of females, an overrepresentation of large males, and a lack of calves and juveniles has detrimental implications for this small narwhal population.
Read the paper — Biological parameters in a declining population of narwhals (Monodon monoceros) in Scoresby Sound, southeast Greenland by E. Garde, O.M. Tervo, M-H.S. Sinding, N.H. Nielsen, C. Cornett, and M.P. Heide-Jørgensen.
