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.
Donaldson
M R
MR
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
Clark
T D
TD
Hinch
S G
SG
Cooke
S J
SJ
Patterson
D A
DA
Gale
M K
MK
Frappell
P B
PB
Farrell
A P
AP
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