open access

https://hdl.handle.net/2115/39885

Relationship between eyed-egg percentage and levels of cortisol and thyroid hormone in masu salmon Oncorhynchus masou

英語

masu salmon

2007-04

Blackwell Publishing

Journal of Fish Biology

70(4)

1045-1056

This study investigated a possible cause of the low eyed-egg percentage that has occurred recently in pond-reared masu salmon Oncorhynchus masou, at the Kumaishi Fish Hatchery Station, Hokkaido, Japan. Serum cortisol levels of masu salmon during the spawning period were compared between individuals from Kumaishi and those from another station (Mori). Cortisol, thyroxine (T4) and triiodothyronine (T3) hormones were also measured in eyed eggs and their levels were compared to the eyed-egg percentage. Serum cortisol levels were significantly higher at Kumaishi than at Mori. There was a good relationship between serum cortisol and fertilized eggs cortisol levels. As cortisol levels in both ovulated females and in the eyed eggs increased, the eyed-egg percentage decreased, indicating a highly significant negative relationship between cortisol levels and eyed-egg percentage. In contrast, as the T3 and T4 levels in eyed eggs increased, the eyed-egg percentage increased. The consistently high cortisol level in serum and eyed eggs observed at Kumaishi may have had a significant effect in lowering the eyed-egg percentage.

学術雑誌論文

Accepted Manuscript

The definitive version is available at www.blackwellsynergy.com

0022-1112

AA00698121