Movement ecology of the Greenland shark (Somniosus microcephalus): Identifying tools, management considerations, and horizontal movement behaviours using multi-year acoustic telemetry

• Main Author: Edwards, Jena Elizabeth
• Format: Master Thesis
• Language: English
• Published: University of Windsor 2020
• Subjects: Arctic ecosystem; Deep-water telemetry; Long-lived species; Marine management; Movement ecology; Arctic; Greenland; Sea ice; Somniosus microcephalus
• Online Access: https://scholar.uwindsor.ca/etd/8414; https://scholar.uwindsor.ca/context/etd/article/9419/viewcontent/uc.pdf

Arctic ecosystems are highly seasonally dynamic, and as such, mobile Arctic species have adopted movement patterns that correspond to the occurrence of productivity hotspots. As polar regions continue to warm at an unprecedented rate, the predictable occurrence of these hotspots of may be reduced, resulting in dire consequences for long-lived or slow-adapting species. Effective marine management approaches will therefore rely on an understanding of the ability of Arctic predators to confer community stability by linking disparate food webs and by responding flexibly to environmental change. This thesis describes the use of static acoustic telemetry to examine the long-term movement patterns of a model mobile predator, the Greenland shark (Somniosus microcephalus) within two distinct habitat types (coastal and offshore waters) and across multiple years (7 y). Movement records for 155 tagged Greenland sharks revealed strong seasonality in coastal and offshore residency driven by fluctuations in sea-ice cover, with evidence of site fidelity to specific sites (receivers) in both regions. Juvenile sharks remained in coastal regions for longer durations than subadults, however, no size-based spatial segregation was observed. At a localized scale, sharks used deep-water channels to direct movements between a coastal fjord system and offshore waters, where they exhibited transient behaviour near offshore moorings located outside of identified hotspot regions. Ultimately, this research provides novel insight into the long-term movement dynamics of this potentially vulnerable Arctic predator and will inform future management practices that promote the longevity of this species.