Serum T4 and serum T3 concentrations in immature captive whitetip reef sharks,Triaenodon obesus

Abstract

Serum T3 (3,5,3′ triiodothyronine) and serum T4 (thyroxine) concentrations were repetitively assayed by radioimmunoassay over a three‐year period in two male and two female immature captive whitetip reef sharks, Triaenodon obesus. These sharks were maintained at the Waikiki Aquarium, Honolulu, Hawaii, in an open system holding pool receiving 568 liters per minute of water from a saltwater well with an iodide concentration of 0.076 mg/liter. No significant male‐female difference was observed for either serum T3 or serum T4. No seasonal pattern of serum T3 was detected (P = 0.07). Serum T3 concentrations ranged (mean ± SEM) from 0.52 to 0.83 ng/mL (0.67 ± 0.01; n = 64). A significant seasonal difference was observed for serum T4 (P < 0.001). Serum T4 concentration was higher in winter (October–January) with a mean (range ± SEM) of 6.58 ng/mL (1.48–8.77 ± 0.35; n = 24) and lower in summer (May–August) with a mean of 3.62 ng/mL (1.34–5.71 ± 0.22; n = 24). The thyroid hormone T4 has a seasonal rhythm even in immature sharks and may have an important role in physiology. J. Exp. Zool. 284:500–504, 1999. © 1999 Wiley‐Liss, Inc.

Comparison of histological features, and description of histopathological lesions in thyroid glands from three species of free‐ranging sharks from the northwestern Atlantic, the blue shark, Prionace glauca (L.), the shortfin mako, Isurus oxyrhinchus Rafinesque, and the thresher, Alopias vulpinus (Bonnaterre)

“…1987; St Aubin & Geraci 1989). In sharks, limited data suggest that migration status might influence thyroid morphology but reproductive status might not (Woodhead 1966; Crow et al. 1999).…”

“…1987). Interestingly, goitre in captive sharks has been described frequently, and it has been linked to low environmental iodine and/or increased concentration of goitrogens in their enclosures (Dimond 1963; Blum & Luer 1985; Uchida & Abe 1987; Crow, Atkinson, Ron, Atkinson, Skillman & Wong 1998; Crow, Ron, Atkinson & Rasmussen 1999). There are only limited, incidental descriptions of the morphology of thyroids in free‐ranging sharks (Crow, Luer & Harshbarger 2001).…”

The influence of light on elasmobranch behavior and physiology: a review

“…More broadly, seasonal rhythms in shark physiology have been observed in five species (Table 1). Concentrations of the reproductive hormone, T4, were found to follow seasonal rhythms in whitetip reef sharks (Triaenodon obesus) by (Crow et al, 1999). Blood cholesterol levels were found to follow seasonal rhythms in small-spotted catshark (Scyliorhinus canicula) by (Valls et al, 2016).…”