Tony Farrell

Area of Expertise:

Tony Farrell is a Canada Research Chair (Tier I) in Fish Physiology, Culture and Conservation and a Professor with a joint appointment in the Zoology Department and the Faculty of Land and Food Systems, UBC. His area of expertise is in integrative and comparative animal physiology as it relates to environmental extremes. He has worked on salmon migratory passage, exercise, handling stress and recovery, sustainable aquaculture and aquatic toxicology. He has particular expertise in salmon cardiorespiratory dynamics, oxygen supply to the heart, blood flow regulation, temperature tolerance and hypoxia tolerance.

Spawning migration of Pacific salmon and climate change elevated river temperatures during physically demanding spawning migrations have been repeatedly associated with adult mortality in Fraser River sockeye. In collaboration with Dr. Scott Hinch, Dr. Kristi Miller and Dr. Steve Cooke, Dr. Farrell has been looking at numerous aspects of the factors that are related to adult and, more recently, juvenile migration success. A central hypothesis was that a failed cardiac function triggers the cardiorespiratory collapse that is now well characterized at supra-optimal river temperatures that are being experienced in recent years. Included in the completed and ongoing projects are:

Dr. Farrell, in collaboration with Dr. Colin Brauner, explored the physiological impacts of parasitic sea lice on juvenile pink salmon just after they enter sea water at 0.3 g body mass. Their study focused on understanding the basic physiology of pink salmon as they enter seawater, artificially infecting fish in a controlled manner and testing subsequent performance for the next month, and studying physiological performance on fish captured with existing lice infections. Included in the completed projects, which are all published, are:

• In experimental infection experiments, 1 sea louse did not kill a 0.3 g pink salmon, but maximum swimming performance and ionic regulation were impacted.
• Even 0.3 g pink salmon are good at ridding themselves of infective stages of sea lice, something observed repeatedly previously, but never accounted for until very recently when sea lice impacts on pink salmon populations were modeled.
• Once pink salmon reach about 0.5-0.7 g in body mass, the negative impact of 1 louse per fish is lost. Similarly, for 1 g pink salmon capture from the wild, swimming performance and ionic regulation were similar for fish with 1 louse and none.
• Abrading skin on a 3 g pink salmon to an area 10X that caused by a typical louse infection had no significant effect on seawater.
• Studies on the seawater preparedness of pink salmon show that they possess an innate smolt-window that peaks around the time of yolk absorption, which only partially triggers the necessary gill ion-regulatory enzymes. Seawater entry complete this process, perhaps explaining some of the early lifestage sensitivity to sea lice.

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