Research Document - 2011/021

Population Genetic Structure of Narwhal (Monodon monoceros)

By S.D. Petersen, D. Tenkula, and S.H. Ferguson

Abstract

Narwhal (Monodon monoceros) is a key element of the eastern Canadian Arctic ecosystem, and is a culturally important species for Inuit. As the Arctic becomes of greater interest for development, and as northern communities grow in size, narwhals will be subject to increasing anthropogenic pressure. There may be additional natural pressures in the form of increased predation by killer whales (Orcinus orca) and frequency of ice entrapments. In the face of these pressures, it is important to actively manage anthropogenic impacts. Currently, this is most effectively done through the establishment of harvest regulations directed at specific stocks. Identification of stock structure is needed to facilitate management both nationally and internationally. To identify stock structure, narwhals from the entire species range were genetically profiled using 16 microsatellite markers. Bayesian analysis to determine the number of genetic clusters without sampling location data was not able to resolve population structure at any level. This was in spite of significant genetic differentiation among the Baffin Bay, Northern Hudson Bay, and East Greenland populations (FST values between 0.011 and 0.028). These results support the population divisions previously established by mitochondrial sequences, contaminant analysis, and satellite telemetry. Within Baffin Bay, partial support was found for the existing stock designations using multivariate analysis to differentiate groups. The analysis suggests that narwhals from Jones Sound and the Somerset Island summering stock are differentiated, although the Somerset Island finding may be influenced by low sample numbers. Increased sampling of most stocks is suggested to increase the understanding of how stocks are related and at what rate migration among stocks may occur.

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