İnek Burunlu Vatoz (Rhinoptera bonasus) Balığının Makroskobik Olarak İncelenmesi

Abstract

The cownose ray, Rhinoptera bonasus, is currently listed as vulnerable and threatened species by the IUCN Red List due to overfishing and bycatch in worldwide resulted declines of the steep population declines of 30-49% in only 43 years. We aimed to present suitable dissection methods for a necropsy of cownose ray with a large, rhomboid-shaped wing-like pectoral disc and compressed dorsoventrally using a specific approach to observe external and internal anatomy. The fish were obtained from a public aquarium after natural death and were dissected with four incision area to open chondrocranium, gills, pericardial cavity and pleuroperitoneal cavity. The dorsal surface of the body is completely naked and smooth, greenish-brown colored, in contrast the ventral surface of the body is white. The liver fills most of the pleuroperitoneal cavity and covers the esophagus, stomach, duodenum, valvular intestine, spleen, kidney and uterus. The valvular intestine or spiral valve is one of the largest organs of the digestive system. In most rays, only the left ovary is developed and functional; therefore, the ovaries of the specimens are located on the left to the median line, close to the cranial end of the pleuroperitoneal cavity, and caudal to the stomach. In conclusion, the presented dissection techniques will enable to examine of the external and internal anatomy of cownose rays and will contribute to a suitable approach to organs.

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“…The fishing operations conducted during breeding seasons, which vary depending on the fish species, result in the separation of fish offspring from their natural environments. For some pregnant fish (such as cownose ray), the dread of being caught during these activities in their natural environments and the stress factors that occur during the transfer to aquariums contribute to offspring mortality [13,14]. The transfer of fish under the threat of extinction from their natural habitats to aquariums negatively affects their feeding, reproduction, migration, and welfare levels.…”