Seasonal changes of thyroid hormones in field‐collected Atlantic cod in relation to condition indices, water temperature and photoperiod
Serum T 4 and T 3 in wild Atlantic cod Gadus morhua ranged from 1 to 12 ng ml −1 and from 2 to 27 ng ml −1 respectively over a 3‐year period. In general, the concentrations increased from summer (T 3 ) or early autumn (T 4 ) to maxima in mid‐winter and declined abruptly during spring. The T 4 /T 3 m...
| Published in: | Journal of Fish Biology |
|---|---|
| Main Authors: | , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Wiley
2000
|
| Subjects: | |
| Online Access: | http://dx.doi.org/10.1111/j.1095-8649.2000.tb00261.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1095-8649.2000.tb00261.x https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1095-8649.2000.tb00261.x |
| Summary: | Serum T 4 and T 3 in wild Atlantic cod Gadus morhua ranged from 1 to 12 ng ml −1 and from 2 to 27 ng ml −1 respectively over a 3‐year period. In general, the concentrations increased from summer (T 3 ) or early autumn (T 4 ) to maxima in mid‐winter and declined abruptly during spring. The T 4 /T 3 monthly means were lowest in summer and highest in winter. The seasonal patterns of thyroid hormones were weakly correlated with changes in water temperature. However, both T 4 and T 3 co‐varied simultaneously with photoperiod. In addition, T 3 was correlated with the hepatosomatic index and condition factor during summer and autumn. It is suggested that the seasonal changes in the release of T 4 from the thyroid were photoperioddriven, and that the course of T3 was regulated by the metabolic state of the fish during the somatic growth period. |
|---|