No abstract

No abstract

No abstract

Arctic waters are warming rapidly due to climate change, which is altering the timing of seasonal sea ice dynamics. Summer ice breakup provides a critical productivity bloom that consumers depend on. Arctic char Salvelinus alpinus undertake seasonal migrations to marine waters presumably to exploit this prey pulse. However, specific migratory timing and residency of char relative to breakup is largely unknown. To investigate char movement, individuals were tagged with acoustic transmitters in 2017 (n = 58) and 2018 (n = 52) within Tremblay Sound, Nunavut, Canada, resulting in 625482 detections. Generalized linear models were used to relate multiple movement metrics to ice conditions as well as biological and temporal factors. Char exhibited multiple migratory patterns (chronologies), by which fish either migrated to/from rivers within Tremblay Sound (n = 67), rivers in external systems (n = 35), or a combination of both (n = 8). Fish that migrated exclusively from external systems were longer (~14 cm) than fish exhibiting other chronologies. Migration timing was related to chronology and preempted the specific ice-off date. Fish migrating from rivers within Tremblay Sound entered the marine environment ~7.5 d before the start of ice-off, while external migrants entered ~21 d after ice-off start. Differing migratory chronologies highlight the complexity of char migrations and may indicate the presence of subpopulations or potential ontogenetic shifts in migration behavior. Our study underscores the importance of the brief ice-free season, with potential implications for climate change resilience and management of this important resource in a changing Arctic.

Recent advancements in telemetry have redefined our ability to quantify the fine-scale movements of aquatic animals and derive a mechanistic understanding of movement behaviours. The VEMCO Positioning System (VPS) is a fine-scale commercial positioning system used to generate highly accurate semi-continuous animal tracks. To date, VPS has been used to study 86 species, spanning 25 taxonomic orders. It has provided fine-scale movement data for critical life stages, from tracking day-old turtle hatchlings on their first foray into the sea to adult fish returning to natal rivers to spawn. These high-resolution tracking data have improved our understanding of the movements of species across environmental gradients within rivers, estuaries and oceans, including species of conservation concern and commercial value. Existing VPS applications range from quantifying spatio-temporal aspects of animal space use and key aspects of ecology, such as rate of movement and resource use, to higher-order processes such as interactions among individuals and species. Analytical approaches have seen a move towards techniques that incorporate error frameworks such as autocorrelated kernel density estimators for home range calculations. VPS technology has the potential to bridge gaps in our fundamental understanding of fine-scale ecological and physiological processes for single and multi-species studies under natural conditions. Through a systematic review of the VPS literature, we focus on 4 principle topics: the diversity of species studied, current ecological and ecophysiological applications and data analysis techniques, and we highlight future frontiers of exploration.