Field assessments of heart rate dynamics during spawning migration of wild and hatchery-reared Chinook salmon

Abstract

During spawning, adult Pacific salmonids ( Oncorhynchus spp . ) complete challenging upriver migrations during which energy and oxygen delivery must be partitioned into activities such as locomotion, maturation and spawning behaviours under the constraints of an individual's cardiac capacity. To advance our understanding of cardiac function in free-swimming fishes, we implanted migrating adult Chinook salmon ( Oncorhynchus tshawytscha ) collected near the mouth of the Sydenham River, Ontario, with heart rate ( f H ) biologgers that recorded f H every 3 min until these semelparous fish expired on spawning grounds several days later. Fundamental aspects of cardiac function were quantified, including resting, routine and maximum f H , as well as scope for f H (maximum−resting f H ). Predictors of f H were explored using generalized least-squares regression, including water temperature, discharge, fish size and fish origin (wild versus hatchery). Heart rate was positively correlated with water temperature, which aligned closely with daily and seasonal shifts. Wild fish had slower resting heart rates than hatchery fish, which led to significantly higher scope for f H . Our findings suggest that wild salmon may have better cardiac capacity during migration than hatchery fish, potentially promoting migration success in wild fish. This article is part of the theme issue ‘Measuring physiology in free-living animals (Part I)’.

The movement ecology of fishes

“…A canonical example of using the movement ecology framework to relate movement to fitness includes the tagging of salmonids during the spawning migration ( e.g ., Cooke et al ., 2014). Combining tagging with experimental manipulation (Birnie‐Gauvin et al ., 2020), nonlethal biopsy (Jeffries et al ., 2014) or the use of tag sensors such as heart rate ( e.g ., Twardek et al ., 2021) or acceleration ( e.g ., Burnett et al ., 2014) allows direct inference of how movement processes affect animal fitness, albeit at brief timescales. Grasping how features of animal movement interface with animal fitness can then empower the use of movement models for conservation planning, fisheries management, habitat restoration initiatives and more.…”

“…Heart rate loggers are increasingly used (e.g., Twardek et al, 2021) whereas radio transmitters equipped with heart rate sensors have been used for decades (Lucas, 1994). Magnetometers have the potential to reveal new insights about fish navigation at finer scales than have ever before been possible using turning angles from path data.…”

“…Studies on individual costs and benefits of movement benefit from integrated acceleration, heart rate or even blood metabolite sensors that log the data or transmit to receivers. Heart rate loggers are increasingly used ( e.g ., Twardek et al ., 2021) whereas radio transmitters equipped with heart rate sensors have been used for decades (Lucas, 1994). Magnetometers have the potential to reveal new insights about fish navigation at finer scales than have ever before been possible using turning angles from path data.…”

Introduction to the theme issue: Measuring physiology in free-living animals

“…For example, the portable and commercially available near infraRed spectroscopy data logging devices introduced in 2006 were originally designed for measuring muscle oximetry in sports athletes [49], but have now also been used to show anticipatory adjustments of blood flow prior to diving in seals [18,50,51]. A wide range of variables can be measured with current physiologging technologies, which includes heart rate [52][53][54][55][56], brain activity [57,58], tissue oxygenation [50,51], respiratory rhythms [59,60] and body temperature [61,62]. When measured simultaneously with other parameters (e.g.…”