HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 297/4/R1136    most recent 00363.2009v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Sandblom, E. Articles by Farrell, A. P. PubMed PubMed Citation Articles by Sandblom, E. Articles by Farrell, A. P.

Articles

Sex-specific differences in cardiac control and hematology of sockeye salmon (Oncorhynchus nerka) approaching their spawning grounds

¹Faculty of Land and Food Systems, University of British Columbia, Vancouver, Canada; ²Department of Zoology, University of Gothenburg, Gothenburg, Sweden; and ³Department of Forest Sciences and ⁴Department of Zoology, University of British Columbia, Vancouver, Canada

Submitted June 26, 2009 ; accepted in final form August 10, 2009

Some male salmonids (e.g., rainbow trout) display profound cardiovascular adjustments during sexual maturation, including cardiac growth and hypertension, and tachycardia has been observed in free-ranging male salmonids near their spawning grounds. In the present study, we investigated cardiac control, dorsal aortic blood pressure, cardiac morphometrics, and hematological variables in wild, sexually maturing sockeye salmon (Oncorhynchus nerka) with a particular aim to decipher any sex-specific differences. Routine heart rate (f_H) was significantly higher in females (52 vs. 43 beats/min), which was due to significantly lower cholinergic tone (28 vs. 46%), because there were no differences in adrenergic tone or intrinsic heart rate between sexes. No differences in blood pressure were observed despite males possessing an 11% greater relative ventricular mass. Concomitant with higher routine heart rates, female sockeye had significantly higher levels of cortisol, testosterone, and 17β-estradiol, whereas the level of 11-ketotestosterone was higher in males. There were no differences in hematocrit or hemoglobin concentration between the sexes. The findings of this study highlight the importance of considering sex as a variable in research fields such as conservation biology and when modeling the consequences of local and global climate change. Indeed, this study helps to provide a mechanistic basis for the significantly higher rates of female mortality observed in previous studies of wild-caught sockeye salmon.

blood pressure; cardiac sympathovagal tone; hemoglobin; hematocrit; sex hormones