SEA-FISHERIES LABORATORY. 115 
amounted to as much as a gramme and a half. Adult sprats, 
measuring 134 millimetres, practically 54 inches in length, 
with the reproductive organs half developed, usually weighed 
19°2 grammes. Young sprats, half that length, only weighed 
1:6 grammes, or just one-twelfth the weight of the adult. 
Kstimations of the oil m the muscle substance were made 
by means of the Soxhlet apparatus, in the manner described 
by Dr. Johnstone on page 154 of the report for 1914. The 
percentage of oil amounted to 9:4, which is practically the 
same as that found in immature sprats collected in May. 
The sprat fishery exhibits a noticeable falling off in 
February, and by March it may become so unproductive 
that it is abandoned. It occasionally happens, however, 
that the invasion of the adults is followed by wandering 
shoals of young clupeoids, chiefly herrmg, which may prolong 
the fishery in a spasmodic manner throughout the summer. 
The departure of the adults is due to natural causes. The 
reproductive organs are advancing towards maturity when 
the fish arrive in the area. Development continues—and by 
the end of February the organs are practically mature. The 
fish then begin to leave the shallow coastal areas to spawn 
in the deeper water where the specific gravity is higher. 
The eggs are buoyant and float near the surface. The larva 
hatches in less than a week. If the spawning took place close 
in-shore, where the adults pass the winter, many of the eggs 
and larvae would be destroyed through stranding. 
During the winter fishery practically the whole of the 
clupeoids sent to the market are sprats, from half grown to 
the adult state. The range in leneth varies from 2} to 53 inches. 
Young herring are seldom met with in the winter catches. 
None of the samples contained more than 2 per cent. These 
proportions are quite reversed in the summer. A sample 
taken at the end of July contained 86 per cent. of young 
herring, and only 14 per cent. of young sprats. The herring 
H 
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