of the Fishery Board for Scotland. 



101 



On looking over these tables, especially the one given on pp. 99, 

 one is struck by the very marked variations in the composition of the 

 muscle of the female at different periods during its reproductive life. In 

 all probability much the same changes occur in the case of the muscles 

 of the male herring during the growth of the testes, but the data which 

 are given are insufficient to warrant one in drawing definite conclusions 

 on this point. 



Summary of Results. 



(1) The tables on pp. 97, 98, show clearly the alteration in the ratio 

 between the weight of the fish and the weight of the ovaries before, 

 during, and after spawning, the variations being produced by the 

 proportionately much greater increase in the ovaries than in the rest of 

 the fish during the period of maturation. 



(2) As the muscles constitute the main source of the nutritive value of 

 the herring, it is most important to recognise the variations in their 

 composition. These are most striking, especially as concerns the 

 percentage of fat, and as this food principle possesses such a high caloric 

 value, any marked decrease in its amount lowers the nutritive value of 

 the fish to a serious extent. 



The lowest fat percentage which was obtained occurred in the large 

 spent herrings obtained from Lochboisdale in February last, and the 

 total amount of fat present in the collective muscles of the average fish 

 was exceedingly small. The percentage amount of water in these 

 muscles was higher than normal, but the proteid and P 2 0 5 percentages 

 were but little affected. 



The herrings obtained from the same district at the close of December 

 of last year contained a slightly larger percentage of fat in their muscles, 

 and of the two series of fish examined those which were spent contained 

 rather less than those which were spawning. 



In the herrings obtained from Helmsdale at the beginning of December, 

 the fat percentage was but little above that of the Lochboisdale spawning 

 fish. Some of these herring were evidently just about to spawn, the 

 ovaries being very large. 



The herrings obtained from Loch Gair about the middle of December 

 show a moderately high percentage of fat, but still markedly lower than 

 in any Loch Fyne herrings caught during the months of September, 

 October, and November. The highest percentage of muscle fat was 

 found in October fish. 



In the summer fish from Loch Fyne, where the ovaries were in an 

 immature condition the fat percentage was usually about that which is 

 often given as the average for the herring. The fat percentage of the 

 herring muscles, therefore, continues rising during the three months, 

 probably, of August, September, and October. It begins to fall slightly 

 in November, markedly in December, most markedly during spawning 

 and continues at a low level until the fish begin to feed again. 



The variations in the total amount of fat present in the muscles of the 

 fish are practically the same as those observed in the percentages, except in 

 cases where the herrings being extremely large — as, for example, the Loch 

 Gair specimens — the absolute amount of fat present remains high although 

 the percentage has commenced to fall. For further details with regard 

 to the fat percentages the reader is referred to the tables. 



The variations in the percentage amounts of proteid are less marked. 

 It is naturally lowest when the fat percentage is highest unless in cases 

 where the amount of water in the muscles is below the average when 

 both proteid and fat may show a fairly high percentage. 



