Reproductive Anatomy of Chondrichthyans: Notes on Specimen Handling and Sperm Extraction. II. Sharks and Chimaeras

Abstract

The chondrichthyan fishes, which comprise sharks, rays, and chimaeras, are one of the most threatened groups of vertebrates on the planet. Given this situation, an additional strategy for the protection of these species could be the ex situ conservation projects developed in public aquaria and research centers. Nevertheless, to increase sustainability and to develop properly in situ reintroduction strategies, captive breeding techniques, such as sperm extraction and artificial insemination, should be developed. These techniques are commonly used in other threatened species and could be also used in chondrichthyans. However, the different reproductive morphologies found in this group can complicate both processes. Therefore, a comparison of the reproductive anatomy of eight distinct chondrichthyans, with an emphasis on those important differences when performing sperm extraction or artificial insemination, is carried out herein. Sharks and chimaeras belonging to the Scyliorhinidae, Carcharhinidae, Centrophoridae, Etmopteridae, Hexanchidae, and Chimaeridae families were obtained from commercial fisheries, public aquaria, and stranding events. In addition, the process of obtaining viable sperm samples through cannulation, abdominal massage, and oviducal gland extraction is described in detail for both living and dead animals.

Hematology and Plasma Chemistry Reference Values in Nursehound Shark (Scyliorhinus Stellaris) Maintained Under Human Care

“…We collected blood samples from 94 clinically healthy Nursehound Shark (47 females and 47 males). We determined gender based on the presence of claspers (copulatory organs only present in males) ( 20 ). We determined body weight (kg) using a crane scale (GRAM CR 150-S, Gram Precision S.L., l'Hospitalet de Llobregat 08907, Spain), and we took measures for total length (snout to tip of the tail; TL, in cm), and snout to vent length (snout to cloaca; SVL, in cm) using a flexible nylon measure.…”

“… Shark were sampled from five different aquaria in Spain. Sex was determined based on the presence of claspers and developmental stage was determined based on their total length ( 17 , 20 ) . …”

“…We submitted all individuals to a fasting period which ranged from 24 to 36 h prior to sampling, as imbalances in plasma chemistry Shark were sampled from five different aquaria in Spain. Sex was determined based on the presence of claspers and developmental stage was determined based on their total length (17,20).…”

Andrology of shortnose guitarfish Zapteryx brevirostris (Müller & Henle, 1841) (Chondrichthyes, Trygonorrhinidae)

“…Both testes were larger in terms of length and width, as well as greater echogenicity, in late April for Raja erinacea (Mitchill, 1825) (Hamlett, 1999) and G. poecilura (Henderson et al, 2013). Although the main function of the gland is still being discussed, it is known that its secretions have a positive effect on the activation of the sperm, thus increasing spermatozoa motility (García-Salinas et al, 2021b;Hug et al, 2000).…”

“…Semen collection in elasmobranchs can occur via abdominal massage or by using a cannula or catheter, inserted through the urogenital papilla (García-Salinas et al, 2021b;Wyfels et al, 2021). Both methods require knowledge of the anatomy of the species being managed.…”