Notes on female reproductive biology and embryos of the brown guitarfish Rhinobatos schlegelii from the Penghu Islands, Taiwan

Schluessel, Vera; Giles, Jenny; Kyne, Peter M.

doi:10.1007/s10228-014-0431-x

Cited by 10 publications

(6 citation statements)

References 11 publications

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“…The weak relationship between litter size and L T found in this study could be due to overall lower mean fecundity in R. leucorhynchus , and that it is common for females to lose embryos as a result of stress during capture. The embryonic sex ratio was not significantly different from 1:1, similar to results reported for several species of Rhinobatidae (Márquez‐Farías, ; Blanco‐Parra, et al, ; Rocha & Gadig, ; Schluessel et al , ). Embryonic growth was negatively allometric, meaning that length increased more rapidly than body mass, a result reported for R. leucorhynchus in Colombia (Payán et al , ).…”

Section: Discussionsupporting

confidence: 88%

“…Rhinobatos leucorhynchus exhibit a simultaneous cycle because vitellogenesis occurs in parallel to embryonic development, as evidenced by continued oocyte growth and observations of pregnant females carrying mature oocytes and term embryos at the same time. This strategy has been recorded in several rhinobatids, including R. productus , R. schlegelii and Z. exasperata (Márquez‐Farías, ; Blanco‐Parra , et al, ; Schluessel et al, ). The presence of uterine eggs year‐round and embryos at different developmental stages suggests asynchronous reproduction.…”

Section: Discussionmentioning

confidence: 85%

“…Uterine fecundity was within the expected range for R. leucorhynchus (Payán et al , ) and was lower in comparison with R. planiceps (nine embryos; M. Carrera‐Fernández, unpubl. data), Rhinobatos schlegelii Müller & Henle 1841 (14 embryos; Schluessel et al, ) and Z. brevirostris (six embryos; Abilhoa et al , ). In contrast to R. leucorhynchus , fecundity is directly related to L T in these species (Márquez‐Farías, ).…”

Section: Discussionmentioning

confidence: 97%

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Reproduction of the whitesnout guitarfish Rhinobatos leucorhynchus in the Ecuadorian Pacific Ocean

Romero-Caicedo

Carrera‐Fernández

2015

Journal of Fish Biology

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Biological sampling of whitesnout guitarfish Rhinobatos leucorhynchus, caught as by-catch in the commercial fisheries on the Pacific coast of Ecuador, was conducted from specimens caught between April 2013 and January 2015, in order to provide further information on the reproductive biology of this species, for which data are limited. Samples comprised 1024 specimens (458 males and 566 females), with the sex ratio (1:1·23) significantly in favour of females. The total length (LT) ranged from 20·5 to 106·0 cm and showed sexual dimorphism, with females attaining a larger size. The relationship between body mass (MT) and LT was not significantly different between sexes. The length at 50% maturity for males based on internal reproductive organs was 60·9 cm LT , which was slightly larger than when based on clasper condition alone (58·5 cm LT). The LT at 50% maturity for females was 57·8 cm, and the LT at maternity was 65·1 cm. Fecundity ranged from one to seven embryos and LT at birth was 20-26 cm. According to oocyte development, two peaks of ovulation were observed (May to June and November to December). The ovarian cycle was estimated at 6 months and gestation between 5 and 6 months. Embryos showed different sizes all year-round, indicating an asynchronous cycle.

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Section: Discussionsupporting

confidence: 88%

Section: Discussionmentioning

confidence: 85%

Section: Discussionmentioning

confidence: 97%

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Reproduction of the whitesnout guitarfish Rhinobatos leucorhynchus in the Ecuadorian Pacific Ocean

Romero-Caicedo

Carrera‐Fernández

2015

Journal of Fish Biology

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“…The most significant impact due capture stress during the reproductive period is capture-induced birth or abortion, characterized by premature expulsion of an embryo (Adams et al, 2018), which could be confirmed by our results. This process has been reported to be common in numerous viviparous species at different stages of development resulting from capture and handling (Zagaglia et al, 2011;Schluessel, Giles & Kyne, 2015;Adams et al, 2018). However, our study brings the first detailed report combined with physiological alterations related to the phenomenon in an elasmobranch.…”

Section: Discussionmentioning

confidence: 75%

Impacts of fisheries on elasmobranch reproduction: high rates of abortion and subsequent maternal mortality in the shortnose guitarfish

Wosnick

Awruch

Adams

et al. 2018

Animal Conservation

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The fate of bycatch species released back into the water is crucial to estimate population status and consequent decisions to implement adequate management measurements for elasmobranchs. The shortnose guitarfish, Zapteryx brevirostris, is an endemic species of the Southwest Atlantic. It is currently listed as 'Vulnerable' both in the International Union for Conservation of Nature and Brazilian red lists. Although this species displays high tolerance to capture and transportation by fishers from the capture site to the fish market, a significant reduction in survival rates is observed during the reproductive period. Thus, the aim of the present study was to examine post-capture and post-commercial transportation consequences in pregnant females obtained as bycatch from artisanal fisheries in Southern Brazil. Results showed high abortion rates and reduced maternal survival after abortion, with all abortions occurring within 28 h of monitoring in laboratory. Stress plasma markers were also evaluated, to determine the physiological consequences of capture-induced parturition to pregnant females. Results showed alteration in all markers measured (plasma urea, pH, lactate, phosphorus, and potassium) with values for dead pregnant females being different from non-pregnant females and those which survived capture and subsequent abortions. The mortality caused by fisheries bycatch may prove difficult to manage, with immediate release and specific handling protocols for pregnant females implemented through environmental education environmental education and fishermen training programs, potential options to maintain adequate maternal survival and recruitment for this species.

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“…A particularly concerning consequence of stress during the reproductive period is abortion, characterized by the spontaneous expulsion of an embryo before it is sufficiently developed to survive (Adams et al ., ). This type of trauma has already been reported for many viviparous elasmobranch species, with involuntary embryo loss at different stages of development because of capture and handling (Adams et al ., ; Rincon, ; Schluessel et al ., ; Zagaglia et al ., ). Thus, a better understanding of possible abortion consequences due to stress of capture is of utmost importance to understand potential effects on reproduction and recruitment in the following year and to develop successful conservation and sustainable management programs.…”

Section: Introductionmentioning

confidence: 99%

Ultrasonography as a promising methodology to indicate captured‐induced abortion in viviparous elasmobranchs

Wosnick

Adams

Freire

2018

Journal of Fish Biology

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This study aimed to characterize morphological aspects related to abortion through a non-lethal approach in the shortnose guitarfish Zapteryx brevirostris, an endemic and threatened species commonly caught by artisanal fisheries. Two females with signs of abortion and one female exhibiting external signs of pregnancy were purchased alive at a fish market during the period when this species has developing embryos in southern Brazil. Scans were conducted using a portable ultrasound. Females with signs of abortion revealed an absence of embryos despite having a similar morphology of the uterus when compared to the pregnant female. Examination of the pregnant female revealed the presence of two embryos, measuring c. 100 mm, each detected through their midline. This study presents new data on uterine macromorphology following successive abortive events in a viviparous elasmobranch species and validates ultrasonography as a diagnostic tool for the species. Ultrasonography is an effective, non-lethal and less-invasive methodology that is recommended for use in future studies of abortion and other reproductive events in elasmobranchs.

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Notes on female reproductive biology and embryos of the brown guitarfish Rhinobatos schlegelii from the Penghu Islands, Taiwan

Cited by 10 publications

References 11 publications

Reproduction of the whitesnout guitarfish Rhinobatos leucorhynchus in the Ecuadorian Pacific Ocean

Reproduction of the whitesnout guitarfish Rhinobatos leucorhynchus in the Ecuadorian Pacific Ocean

Impacts of fisheries on elasmobranch reproduction: high rates of abortion and subsequent maternal mortality in the shortnose guitarfish

Ultrasonography as a promising methodology to indicate captured‐induced abortion in viviparous elasmobranchs

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