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Effects of oestradiol‐17β or 17α‐methyltestosterone administration on gonadal differentiation of largemouth bass Micropterus salmoides (Lacepède)
Author(s) -
Arslan Tulin,
Phelps Ronald P,
Osborne Jason A
Publication year - 2009
Publication title -
aquaculture research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.646
H-Index - 89
eISSN - 1365-2109
pISSN - 1355-557X
DOI - 10.1111/j.1365-2109.2009.02286.x
Subject(s) - micropterus , methyltestosterone , bass (fish) , biology , androgen , endocrinology , medicine , oral administration , sexual differentiation , zoology , fishery , hormone , biochemistry , gene
Monosex populations can be a valuable management tool in culture of larger size largemouth bass (>400 g). In this study, we investigated the effective mode and duration of oestrogen and androgen administrations to produce monosex largemouth bass populations. The experiment consisted of nine treatments. In oral administration groups, we fed 40‐day‐old fry either 200 mg of an oestradiol‐17β (E 2 ) kg −1 diet or 60 mg of a 17α‐methyltestosterone (MT) kg −1 diet for 30, 45 or 60 days. In bath treatments, we immersed fry in a 1 mg MT L −1 solution for 5 h a day on three or six occasions. For control treatment, we fed fry an ethanol‐treated diet for 45 days. The frequency of females in the control group was 53.1%. Oral administration of E 2 at all durations resulted in slight increases in the frequency of females (59.8–70.5%). Both modes of androgen administration at all durations were ineffective in altering phenotypic sex. The experimental results of our study indicated that male differentiation passed the point of being completely and functionally influenced by exogenous oestrogens, while female differentiation had already taken place and was no longer responsive to exogenous androgens in 40‐day‐old (33.5 mm) largemouth bass fry.