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

Abstract

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.

Evidence of tide pool use by a viviparous elasmobranch as a parturition site

“…Dynamics of the tide pool of the presently reported study; (A) rocky shore located in Arraial do Cabo, Rio de Janeiro, Brazil. The black arrow points to the tide pool location; (B) tide pool being formed via connection with the intertidal zone; (C) tide pool during the isolation period; (D) tide pool in the late afternoon, being slowly connected to the intertidal zone in one of the females, morphological alterations consistent with parturition in viviparous elasmobranchs (Wosnick et al 2018).…”

The role of aquaria in the advancement of elasmobranch reproductive biology

“…For oviparous species, in particular, aspects of their reproductive life history (such as fecundity and embryo development time) are particularly difficult to estimate in the field but are crucially important. Despite the limitations of field samples, fecundity is a fairly reliable metric that can be estimated for viviparous species because the number of young can directly be associated with an individual female, assuming she does not spontaneously abort prior to sampling (Wosnick et al, 2018). For oviparous species, point-in-time sampling to quantify fecundity is not possible since females lay clutches of eggs over a reproductive period that can last for months (Wyffels et al, 2021;Adams et al, 2022).…”

Primeiro registro de eversão vaginal em Psammobatis rutrum Jordan, 1891 (Rajiformes: Arhynchobatidae)

“…Outro fator responsável por este quadro pode estar associado a dificuldades durante o parto/ ovoposição (distocia), como observado para diferentes grupos zoológicos, incluindo peixes (Wildgoose, 2000;Asiimwe et al, 2014;Gal, Baska, Farkas, Mándoki, & Szabó, 2014;Manjunatha, Girish & Narayanaswamy, 2016;Staggs, 2016;Van Zeeland, 2016;Chaudhari et al, 2018;Leite, Wosnick, Giareta & Freire, 2020). Assim, no presente estudo também podemos considerar que a eversão da parede vaginal pode ter sido resultante de um processo de prolapso pélvico intensificado por um evento de cópula malsucedido, postura repentina de ovos devido ao estresse, ou ainda à distocia, geralmente relacionada ao tamanho e posicionamento anormal de ovos/ embriões ou a problemas de contração abdominais (Noakes, Parkinson, England & Arthur, 2001;Henningsen, Smale, Garner & Kinnunen, 2004;Eid-Arimoku & Trompetas, 2011;George et al, 2017;Wosnick, Adams & Freire 2018;Wosnick et al, 2019;Akpan, Akpanika, Nwagbara, Asibong, & Etuk 2019;Leite et al, 2020).…”