EXTENDED ABSTRACT ONLY- DO NOT CITE

• Main Authors: Stephen D. Mccormick, Michael F. O’dea, Amy Moeckel, Björn Thrandur Björnsson
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Atlantic salmon
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.587.7675; http://www-heb.pac.dfo-mpo.gc.ca/congress/2002/ionreg/mccormick.pdf

The parr-smolt transformation is a hormone-driven developmental process that is adaptive for downstream migration and seawater entry. Recently, environmental estrogens such as nonylphenol have been implicated in reduced returns of Atlantic salmon in the wild (Fairchild et al. 1999). Previous research has shown that sex steroids interfere downstream migratory behavior and the development of salinity tolerance that normally occurs during smolting (Madsen et al., 1997; Munakata et al. 2000). The present study was designed to determine the endocrine pathways through which sex steroids and their agonists may act to affect the parr-smolt transformation. Junvenile Atlantic salmon were injected with 0.5, 2, 10, 40 and 150 ug/g branched 4-nonylphenol and 2 ug/g estradiol-17B during the parr-smolt transformation in late March and sampled 1 and 2 weeks after first exposure. Treatment with estradiol and 150 ug/g nonylphenol resulted in lower salinity tolerance after two weeks of exposure. Plasma insulin-like growth factor I (IGF-I) was 30-60 % lower in estradiol and 150 ug/g nonylphenol treated fish