Vol. 64, 2025
Hematology and Plasma
Biochemistry in Whale Sharks (Rhincodon
typus): Baseline Reference Intervals Based on Captivity Status,
Blood Sampling Sites, and Handling Methods
Takaomi
Ito1,* and Takao Segawa2
doi:-
1Osaka
Aquarium Kaiyukan, 1-1-10 Kaigandori, Minato-ku, Osaka 552-0022, Japan.
*Correspondence: Tel +81-6-6576-5545. E-mail: ito@kaiyukan.com (Ito)
2Nihon University Veterinary Research Center, 1866
Kameino, Fujisawa, Kanagawa, 252-0880, Japan. E-mail:
segawa.takao@nihon-u.ac.jp (Segawa)
(Received 15 June 2024 /
Accepted 12 January 2025 / Published -- 2025)
Communicated by Chien-Hsing Lin
This study aimed to establish
reference intervals for red and white blood cell counts, hematocrit
levels, mean corpuscular volume, and 25 key plasma biochemistry
parameters in captive and wild whale sharks (Rhincodon typus). Blood
samples were collected from the caudal vein (CV) and dorsal cutaneous
vein (DCV) of 30 wild sharks caught in fixed nets off the Kochi
Prefecture coast, Japan, and from 24 captive sharks between 2007–2023.
Samples were obtained from restrained captive and wild sharks as well
as unrestrained captive sharks trained for husbandry. Comparative
analyses considered three factors: captivity status (wild vs. captive
sharks under restraint), blood sampling sites (CV vs. DCV under
restraint), and handling methods (DCV sampling under restrained vs.
unrestrained conditions). Analysis of captivity status revealed
significant differences in 12 of 29 parameters, with triglyceride
levels significantly lower in wild sharks, possibly indicating
nutritional deficiencies due to their prolonged migrations. Comparisons
of blood sampling sites revealed significant differences in 11
parameters, including red and white blood cell counts and hematocrit
levels, with most CV-derived parameters being higher than those from
the DCV. A strong correlation (r > 0.7) was found between the CV and
DCV for 19 parameters, indicating predictive values between these
vessels. Additionally, the relationship between RBC, Ht, and MCV
indicates that the RBC and MCV results may not be entirely reliable and
should therefore be interpreted with caution. In the handling method
comparison, eight parameters exhibited significant differences;
specifically, aspartate aminotransferase, ammonia, and creatine
phosphokinase levels were likely influenced by stress effects,
including restraint-induced muscle damage. These findings emphasize the
importance of unrestrained blood collection, facilitated through
husbandry training, for accurate blood parameter evaluations.
Integrating statistical results across the three studied factors
allowed for the establishment of reference intervals, means, and
medians for whale sharks, contributing to health management in captive
sharks and conservation in wild populations.
Key words: Shark health assessment,
Comparative blood analysis, Captive vs. wild comparison, Husbandry
training
Citation: Takaomi Ito T, Segawa T. 2025.
Hematology and plasma biochemistry in whale sharks (Rhincodon typus):
baseline reference intervals based on captivity status, blood sampling
sites, and handling methods. Zool Stud 64:01.

Supplementary
materials: Table S1
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