Investigation into the fat content in the sardine tissues (Clupea pilchardus Walb.)
Abstract
Basing on investigations dealing with the fat content in the sardine tissues, which were carried out from May to October 1949, with the purpose to establish its relation to the length, sex, and the stage of maturity, as well as to observe the variation of fat content during the fishing season of that clupeid species, the following facts have been recorded:
1) During the period of these investigations a somewhat higher amount of fat present in the tissues was generally shown by sardine measuring 16 cm and upwards than by specimens having a total length from 12 to 16 cm.
2) The fat content in the sardine tissues varied in a wide range from May to October. The lowest values of this fat could be found in May, and the highest ones in August and September. The minimal amount of fat found in May was probably in connexion with the termination of sexual activity of sardine. The regaining of fat in the tissues could be observed in May, and it took place in a relatively short time. The decrease of the amount of fat present in the sardine tissues in July, as shown by analyses, has not been wholly explained. The fat content in the tissues at the beginning of the sardine ripening was relatively high.
The amount of the periintestinal fat, approximately estimated during the parallel biometrical analyses of sardine catches, showed a similar course in their general features. The highest value of the periintestinal fat could be observed in August, whilst a certain decrease of it was manifest already in September.
3) Fish measuring 16 cm and upwards, and those from 12 to 16 cm generally showed a similar course as to the variation of fat content in the tissues during the period extending from May to October. The maximal amount of fat appeared earlier in larger fish than in smaller ones. The same applies also to the definitive decrease of the fat content in the tissues preceding the spawning season.
4) Sardine of equal length, catched on different localities during a short time interval, did not show always the same amount of fat present in the tissues.
5) During the period of these investigations, the sardine males showed in most cases a somewhat higher fat content in the tissues than the females. The samples yielding a higher amount of fat in females belonged to the time of minimal fat content or of its downward trend. The observed differences between the sexes might, however, have been influenced by the individual variations of fat content.
6) A considerable influence of the advanced stage of maturity (III, IV) on the fat content could be observed in May, that is after the termination of the spawning season. The initial ripening of sardine before the begining of the spawning season did not notably affect the amount of fat in the tissues and of the periintestinal fat.
