A practical guide for assigning sex and stage of maturity in sturgeons and paddlefish

Abstract

The goal of this paper is to improve the assignment of sex and stage of maturity for sturgeons and paddlefish by providing both an overview of the gonadal stages of maturity and general guidelines and training needs for the four most commonly used techniques to assign sex and stage of maturity including ultrasound, endoscopy, plasma sex steroid analysis, and biopsy of the gonads via celiotomy. Sturgeons and paddlefish do not express external sexual dimorphism, which can make assignment of sex and stage of maturity challenging. Correct assignment of sex and stage of maturity is important for management of wild populations as well as for aquaculture, whether for conservation or commercial production. Selecting a technique to use when assigning sex and stage of maturity will depend on a number of factors; a comparison among these techniques is provided in this review, including tradeoffs, to help assist in technique selection based on specific research or production goals. The use of more than one technique may be beneficial to determine error rates associated with a single technique. This review is intended to serve as a practical resource when assigning sex and stage of maturity in field or laboratory settings in addition to stressing the importance of correctly identifying sex during research and in the management of populations.

Reproductive ecology and movement of pallid sturgeon in the upper Missouri River, Montana

“…Sturgeon species are not sexually dimorphic; thus, several tools (minor biopsy, ultrasound, endoscopy, and blood plasma sex steroid concentrations) have been developed to determine sex and stage of maturity (Webb, Van Eenennaam, Crossman, & Chapman, ). Pallid sturgeon were assigned to reproductive classifications based on sex (male [M], female [F], or unconfirmed [U]), maturity (reproductively‐active [RA] or non‐reproductively‐active [NRA]), and origin (hatchery‐origin [HO] or wild [W])).…”

“…Sex steroid (testosterone [ T ] and estradiol‐17β [ E 2]) concentrations in blood plasma were measured by radioimmunoassay (RIA) to determine sex, stage of maturity, and ovulatory success when combined with other techniques (Webb & Doroshov, ). In the field, blood samples were collected from the caudal vasculature using a 2 ml syringe and processed according to the protocol described in Webb et al (). Frozen plasma samples were stored at −20 to −80°C prior to analysis in the lab.…”

“…In addition to blood plasma sex steroid analysis, gonadal biopsies were collected after visual examination of the gonads to determine sex, stage of maturity, and spawning readiness (Webb et al, ). Ovarian follicles were collected from ripe females for macroscopic analysis and calculation of oocyte Polarization Index (PI) in the laboratory.…”

Using machine learning algorithms to analyse the scute structure and sex identification of sterlet Acipenser ruthenus (Acipenseridae)

“…However, sturgeons have no reliable external sexual characteristics, as previously described (Chebanov & Galich, ; Fopp‐Bayat, ). Currently, to determine sex, hormonal (Du et al, ; Mosyagina & Zelennikov, ; Wheeler, Novak, Wippelhauser, & Sulikowski, ), biochemical (Barulin, ; Yarmohammadi et al, ), histological methods (Golpour et al, ) and biopsy, laparoscopy (Falahatkar & Poursaeid, ; Webb, Eenennaam, Crossman, & Chapman, ), endoscopy (Munhofen, Jiménez, Peterson, Camus, Jiménez, Peterson, Camus, & Divers, ) are used. Above methods have difficulties with mass application in aquaculture and can have a high error (the first two methods) or can traumatize fish (the last four methods).…”

“…Furthermore, a sturgeon sex gene has not been found, unlike most fish species (Fopp‐Bayat, ; Keyvanshokooh & Gharaei, ; Khodaparast, Keyvanshokooh, Pourkazemi, Hosseini, Keyvanshokooh, Pourkazemi, Hosseini, & Zolgharnein, ; Vizziano‐Cantonnet, Di Landro, & Lasalle, ); however, a study in this area are still under way (Burcea et al, ; Havelka, Fujimoto, Hagihara, Adachi, Fujimoto, Hagihara, Adachi, & Arai, ; Vizziano‐Cantonnet et al, ; Vizziano‐Cantonnet, Lasalle, DiLandro, Klopp, & Genthon, ). Currently, the ultrasound diagnostics is the most successful method of early sturgeon sex determination (Chebanov & Galich, ; Memiş et al, ; Webb et al, ) and can determine the sex starting from 2 years for Sterlet sturgeon ( Acipenser ruthenus ), from 2–3 years for Siberian ( A. baerii ) and Russian ( A. gueldenstaedtii ) sturgeons, from 3–4 years for White sturgeon ( A. transmontanus ) and from 4–5 years in Beluga ( Huso huso ) (Chebanov & Galich, ). However, the ultrasonic diagnostics requires the expensive equipment and high qualification of fish farmers.…”