QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by SWIFT, D. R. Search for Related Content PubMed Articles by SWIFT, D. R.

Journal of Experimental Biology 32,751-764 (1955)
Published by Company of Biologists 1955

Seasonal Variations in the Growth Rate, Thyroid Gland Activity and Food Reserves of Brown Trout (Salmo Trutta Linn.)

D. R. SWIFT ¹

¹ Freshwater Biological Association The Ferry House, Far Sawrey, Ambleside

1. Seasonal variations in the growth rate, food reserves and activity of the thyroid gland of hatchery-reared brown trout have been investigated.

2. Two peaks of maximum growth rate were found, in spring and autumn. A marked depression of rate occurred during midsummer and winter.

3. Fat which was laid down along the mesenteries and pyloric caecae was found to be the main food reserve. Glycogen was found in small quantities in the liver and muscle. The composition of the muscle and liver was constant except for an autumnal fall in the female liver glycogen level. The fat reserves reached a peak of 23% by weight of the gut wall during July then fell to 5% in autumn.

4. Maturation of the gonads commenced in females in June and in males in July and was completed during October. The protein content of the ovary increased by 16%, and of the testis by 10%. The fat content of the ovary increased by 3%.

5. A new method is described for the determination of thyroid activity in fish using radioactive iodine. Peak thyroid activity was found to occur in midsummer.

This article has been cited by other articles:

				U. G. Reinhardt Asset protection in juvenile salmon: how adding biological realism changes a dynamic foraging model Behav. Ecol., January 1, 2002; 13(1): 94 - 100. [Abstract] [Full Text] [PDF]