Abstract
The spiny butterfly ray (Gymnura altavela) is a species of ray of the family Gymnuridae distributed among coastal waters of the Atlantic Ocean, Mediterranean Sea, and Black Sea, classified as critically endangered in Europe and endangered worldwide (IUCN Red List) due to declining populations primarily because of fishing pressure and habitat destruction.1 Hematology provides us with important information regarding the health status of individuals and may improve the knowledge to monitor health and detect diseases in rays maintained under human care.2 The objectives of this study were to describe blood cell morphology plus hematological parameters of wild spiny butterfly rays. Twenty-one adult females were caught and released in Los Cristianos, a shallow beach of Tenerife (Canary Islands, Spain), to implant visual and acoustic tags. Blood was collected from the caudal vein of 19 of these animals. We observed all the leukocytes described in elasmobranchs;3 lymphocytes were the dominant leukocyte (60.4%), followed by heterophils or fine eosinophilic granulocyte (21.4%), eosinophils or coarse eosinophilic granulocyte (14.4%), monocytes (2.84%), neutrophils or non-eosinophilic granulocytes (0.84%) and basophils (0.05%). Median blood values were 358000 cells/µL for total red blood cell count; 34233 cells/µL for total white blood cell count; 25.1% for packed cell volume. The data provided in this study should improve our understanding of this species and can be used as a guideline for routine health monitoring in spiny butterfly rays maintained under human care.
Acknowledgments
We would like to thank Loro Parque Fundación and the regional government of the Canary Islands for supporting this work under the umbrella of CanBio project and also, special thanks are given to the Save Our Seas Foundation and Rays of Paradise project and to all those involved in tagging and sample collection.
*Presenting author
+Student presenter
Literature Cited
1. Dulvy NK, Charvet P, Carlson J, et al. Gymnura altavela. The IUCN Red List of Threatened Species. 2021:e.T63153A3123409.
2. Grant KR. Fish Hematology and Associated Disorders. Vet Clin North Am Exot Anim Pract. 2015;35:681–701.
3. Carmezim HS, Marcos R. There is plenty more fish nomenclature in the sea: The elasmobranch granulocytes. Vet Clin Pathol. 2020;49:196–197.