Gametogenesis and Sex Steroid Profiles in Cultured Coho Salmon (Oncorhynchus kisutch, Walbaum)
Author
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Estay, Francisco
Author
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Neira Roa, Roberto
es_CL
Author
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Díaz, Nelon F.
es_CL
Author
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Valladares Boasi, Luis
es_CL
Author
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Torres, Alfredo
es_CL
Admission date
dc.date.accessioned
2014-01-03T13:53:16Z
Available date
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2014-01-03T13:53:16Z
Publication date
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1998
Cita de ítem
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THE JOURNAL OF EXPERIMENTAL ZOOLOGY 280:429–438 (1998)
en_US
Identifier
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https://repositorio.uchile.cl/handle/2250/119637
Abstract
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The gametogenesis of a 2-year-old coho salmon broodstock population cultured in
a fish farm in southern Chile was studied. Gonadosomatic index (GSI), microscopic gonadal traits,
and serum levels of estradiol-17b(E2), testosterone, and 17a,20b-dihydroxy-4-pregnene-3-one
(17,20P) in both sexes were recorded beginning 9 months before spawning in bimonthly samplings.
Maximum GSI means were reached during May, the month of spawning, with 16.8 ± 4.1%
for females and 8.4 ± 0.8% for males, both values within the range described in the literature. GSI
in males, however, was triple that of females during January, showing a faster rate of gonadal
growth in males in early summer. Gonadal microscopy for both sexes showed stages corresponding
to those described by different authors for other salmonids such as rainbow trout. The secondary
vitellogenesis period was 4 to 5 months and corresponded with the short vitellogenesis model
described in rainbow trout for broodstocks maturing at 2 years of age. The serum profiles of sex
steroids in both sexes are consistent with those described in coho salmon and other salmonid
species. In females, E2 and 17,20P show opposite profiles, reaching their maximum levels (E2:
45.13 ± 11.3 ng/ml; 17,20P: 24.47 ± 7.34 ng/ml) during vitellogenesis (March) and ovulation (May),
respectively. In both sexes, testosterone concentration shows maximum levels in May (females:
61.68 ± 15.75 ng/ml; males: 107.8 ± 11.6 ng/ml), suggesting the physiological importance of this
hormone during maturation, either directly or as a substrate for the synthesis of other hormones.
In males, the maximum level of 17,20P (22.33 ± 4.5 ng/ml) also occurs in May during total spermiation,
which confirms its role in semen production and semen fluid regulation as described in
the literature about this hormone in salmonid males. On the basis of the data obtained, a reproductive
pattern is proposed for 2-year-old salmon cultured in southern Chile.