Physiological responses of free-swimming adult coho salmon to simulated predator and fisheries encounters.
The responses of free-swimming adult coho salmon (Oncorhynchus kisutch) to simulated predator and fisheries encounters were assessed by monitoring heart rate (f(H)) with implanted data loggers and periodically taking caudal blood samples. A 10- or 30-min corralling treatment was conducted to simulate conspecifics being cornered by a predator or corralled by fisheries gear without physical contact. Corralling rapidly doubled f(H) from ∼31 beats min(-1) to a maximum of ∼60 beats min(-1), regardless of the duration of the corralling. However, recovery of f(H) to precorralling levels was significantly faster after the 10-min corralling (7.6 h) than after the 30-min corralling (11.5 h). An exhaustive-exercise treatment (chasing for 3 min, with physical contact) to simulate a predator chasing a fish to exhaustion or a fish becoming exhausted after encountering fisheries gear resulted in increased f(H) (to 60 beats min(-1)), plasma lactate, glucose, sodium, osmolality, and cortisol (males only) and a significant decrease in mean corpuscular hemoglobin concentration. Recovery of f(H) and most blood variables was complete about 16 h after exhaustive exercise and handling. The results illustrate a clear relationship between the intensity of exercise and the duration required for recovery of f(H). Changes in f(H) were significantly correlated with those in plasma lactate, chloride, and sodium at 1 h after the exercise treatment protocols. Thus, measurements of f(H) may provide an accurate indication of the general physiological response of salmonids to exhaustive exercise in the natural environment.
Pacific Salmon Ecology and Conservation Laboratory, Centre for Applied Conservation Research, and Department of Forest Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada. michael.r.donaldson@gmail.com
M R
MR
Donaldson
T D
TD
Clark
S G
SG
Hinch
S J
SJ
Cooke
D A
DA
Patterson
M K
MK
Gale
P B
PB
Frappell
A P
AP
Farrell
D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D004924:Escape Reaction / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006854:Hydrocortisone / Q000097:blood; D007773:Lactates / Q000097:blood; D008297:Male; D009068:Movement / Q000502:physiology; D017684:Oncorhynchus kisutch / Q000097:blood / Q000502:physiology*; D009994:Osmolar Concentration; D012964:Sodium / Q000097:blood; D013312:Stress, Physiological / Q000502:physiology
D001786:Blood Glucose; D007773:Lactates; D012964:Sodium; D006854:Hydrocortisone