Plasma Cortisol and Chloride
Stress Responses in Juvenile Walleyes during Capture, Transport, and
Stocking Procedures
B.A. Barton, A.H. Haukenes, B.G. Parsons; J.R.
Reed-2003
North American Journal of Aquaculture, 65(3):
210–219
Abstract:
Extensively reared juvenile walleyes Stizostedion
vitreum subjected to capture and transport stressors associated with
stocking procedures in South Dakota and Minnesota displayed acute increases
in plasma cortisol and extended declines in concentrations of plasma
chloride. In four separate South Dakota transport hauls, mean plasma
cortisol in walleyes rose from 12–49 ng/mL at the time of trap-net capture
to 138–174 ng/mL after 1 h of transport; these concentrations remained
increased at 3 h. Plasma chloride decreased by about 19% during this period;
by 3 h, mean values had dropped about 30%, to 53–61 meq/L. Similarly, in
Minnesota mean plasma cortisol in captured and transported walleyes
increased from 13–26 ng/mL during trap-net capture to 154–214 ng/mL by 1
h after transport in three separate trials and remained at the higher values
at 3 h posttransport. Mean plasma chloride concentrations dropped about 28%,
to 65–72 meq/L, by 3 h after transport and remained significantly
decreased at 68–82 meq/L 24 h later, even though plasma cortisol, an acute
stress indicator, had returned to near pretransport values. Results from
these experimental transport hauls indicate that the juvenile walleyes
experienced considerable physiological stress when captured and transported
to lakes for stocking. This stress was reflected by an appreciable decrease
in plasma chloride that failed to recover to pretransport values after 24 h,
which suggests a possible mechanism for poststocking mortality.
(Department of Biology and Missouri River Institute, University of South
Dakota, Vermillion, South Dakota 57069, USA)