Title
Reproductive structure of the adult green sturgeon, Acipenser medirostris, population in the Rogue River, Oregon
Author(s)
Webb, M.A.H.; Erickson, D.L.
Published
2007
Publisher
Environmental Biology of Fishes
Abstract
The primary objective of this study was to determine the reproductive structure of the adult green sturgeon population in the Rogue River. Green sturgeon were captured by gillnet in the lower 11.6-68.4 river kilometers in April to July 2000-2003 and September and October 2002-2003. Gonadal tissue, collected by biopsy, was processed histologically, blood was collected from the caudal vasculature, and fork length (FL) and total length (TL) (±0.5 cm) were measured for each individual. Sex steroids, testosterone (T), 11-ketotestosterone (11-KT), and estradiol-17ß (E2), were measured by radioimmunoassay. Biological samples were collected from a total of 88 green sturgeon of which 37 females and 41 males were confirmed by histological analysis. Four gravid females, captured in the spring, were visually identified, and oocyte polarization index and ovarian follicle diameter indicated that these females were in spawning condition. Gonadal samples collected from six individuals did not contain gonial cells, hence the sex and stage of maturity in these individuals remains unknown. Of the 20 females captured in the spring, 1 was vitellogenic, 4 were post-vitellogenic, and 15 were post-ovulatory. Twenty-one females were captured in the fall of which 6 were pre-vitellogenic, 7 vitellogenic, and 8 post-ovulatory. Of the 16 males captured in the spring, 2 were pre-meiotic, 8 were ripe or actively spermiating, and 6 were post-spermiation. Twenty-five males were captured in the fall: 11 pre-meiotic males and 14 post-spermiation. The majority of green sturgeon captured in the Rogue River were reproductively active or had recently spawned indicating the importance of this river for the preservation of green sturgeon. © 2006 Springer Science+Business Media B.V.
Keywords
fish; gillnet; histology; immunoassay; reproduction; sex hormone; sexual maturity; spawning; testosterone; North America; Oregon; Rogue River; United States; Acipenser medirostris; Green sturgeon; Reproduction
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PUB10686