Center of Expertise in Marine Mammalogy

Scientific Research Report
2015-2017

Table of Contents

• Complete Text
• Introduction
• Using aerial infrared images to count ringed seals on ice
• The use of unmanned aerial vehicles (UAV)
• 2017: A Marine Mammal Odyssey, Eh!
• Mark-recapture analysis from long-term study on Sable Island identifies changes in demographic rates in northwest Atlantic Grey Seals
• OTN – Using grey seals (Halichoerus grypus) as bioprobes to estimate phytoplankton biomass
• Northwest Atlantic International Sightings Survey (NAISS) of Marine Megafauna on the Continental Shelf From Northern Labrador to the Bay of Fundy
• Monitoring Movements of Whelping Seals on Drifting Pack Ice
• Marine Mammal Genomics Research in the Central and Arctic Region
• OTN and predator-prey interactions
• Listening in on the Deep: Passive Acoustic Monitoring of Whales off Nova Scotia
• Sharing Meals Keeps Killer Whale Families Together: Provisioning relatives maintains long-term social bonds and helps pass on shared genes
• New developments in the use of fatty acids to determine marine mammal diets
• More than a mouthful – unlocking bowhead whale foraging and reproductive histories from baleen
• Observing walrus behaviour at haulout sites in quasi real-time
• Moving towards automated counting
• References

Marine Mammal Genomics Research in the Central and Arctic Region

Lianne Postma and Denise Tenkula

Over the last couple of decades, the use of genetic tools (the study of genes) has become the gold standard to define units (populations, stocks) for conservation and management of marine mammals. Especially in the Arctic, DFO has been a leader in using population genetic research to identify distinct stocks of marine mammals in Canada, monitor the impacts of subsistence harvests on these stocks, and understand how historical environmental events may have shaped current migration and distribution patterns.

For many years, sequencing portions of the control region (CR) in mitochondrial DNA (mtDNA) of belugas (Delphinapterus leucas) has provided valuable insight for conservation and population studies for these whales. However, the advantages of increasing the overall amount of mtDNA sequence and including mtDNA protein-coding genes for investigating stock structure and phylogenies has been demonstrated in other species, including other cetaceans. A next-generation workflow was developed to sequence complete mitochondrial genomes (mitogenomes) for population studies of belugas and narwhals (Monodon monoceros). In a recent study, a total of 106 belugas and 94 narwhals from across each species’ Canadian range were sequenced, which resulted in complete mitogenomes for all samples.

Genetic diversity and phylogenetic analyses of beluga mitogenomes supported previous results found with CR sequence, but finer resolution of sub-groups were found that further inform our understanding of stock structure and evolutionary relationships among the sample groups. Preliminary tests of selection detected the presence of negative, or purifying, selection on all protein-coding genes of belugas, particularly for the ND₁, CO₁ and CO₂ genes. However, no signals of positive selection were detected with the analytical methods used. In contrast to belugas, narwhal mitogenomes continued to exhibit much lower levels of genetic diversity and offered no improvements compared to previous approaches to resolve phylogenetic relationships among geographic sample collections. This could be due to insufficient numbers of samples for the analyses.

Future studies will also focus on highly informative genomic approaches (the study of whole nuclear genomes) that have the potential to inform even more complex questions about the adaptive potential of marine mammals to a changing climate and their role in the ecosystem. Genomics research has been applied to understanding and monitoring the potential of animals to adapt and persist in polluted habitats, the physiological and health conditions of individuals, range shifts of animals in response to changing environments and changing prey availability, and novel perspectives on ecosystem processes, such as nutrient and energy flux.