Development of a protocol for control of gonadal differentiation through sex steroid administration in the Arctic char (Salvelinus alpinus)

Arctic char (Salvelinus alpinus) underwent oral administration of 17 {dollar}alpha{dollar}-methyltestosterone(MT) and estradiol-17{dollar}beta{dollar}(E{dollar}sb2{dollar}) to induce masculinization or feminization, respectively. Drugs were administered for 600{dollar}spcirc{dollar}C days from swim-up. Controls were developed in conjunction with the treatment groups. Histological examination showed a 60:33 male:female ratio in the MT-treated group(n = 196) with 7% intersex, and a 36:49 male:female ratio in the E{dollar}sb2{dollar}-treated group(n = 192) with 15% intersex. Controls(n = 194) yielded a 55:45 male:female ratio, with 0% intersex. Steriod-treated fish were smaller than controls but had a higher condition factor. Conclusions were that the labile period of A. char occurs physiologically earlier than swimup, and therefore immersion therapy at an earlier developmental stage might be more efficacious. A non-aromatizable androgen and more potent estrogen could improve the rates of masculinization and feminization.; The second segment consisted of testing 5 experimental variables utilizing 17{dollar}alpha{dollar}-methyldihydrotestosterone(MDHT) and ethynylestradiol-17{dollar}alpha{dollar}(EE{dollar}sb2{dollar}) in aqueous solutions. (Abstract shortened by UMI.)...