SEA-FISHERIES LABORATORY. 715 
Work aT PIEL. 
Mr. Scott has supplied the customary report on the 
events of the year at our Piel Hatchery, and has given a 
brief account of those investigations which it has been 
possible for him to carry on under the War restrictions which 
are imposed upon his work. His remarks and statistics in 
connection with the Periwinkle fishery are of special interest. 
PLANKTON INVESTIGATIONS. 
We have been able to carry on during the past year the 
periodic collection of plankton samples in Port Erin Bay, 
and these samples have been investigated in detail by 
Mr. Scott and treated statistically by Miss Lewis in the 
usual manner. ‘he detailed statements, tables and curves 
for the various dominant groups of plankton organisms are 
kept in reserve for publication in detail some time in the 
future. It may suffice now to state that, as in the previous 
year, I was able during 1917 to take a series of additional 
gatherings from the motor boat during the two critical 
periods—spring (April) and autumn (August and September) 
—when the Diatoms and Copepoda are respectively present 
in greatest abundance. ‘These gatherings show that the 
vernal maximum in 1917 extended from the middle of April 
to the middle of May, while the Copepoda reached their 
maximum in August. 
One conclusion that is becoming clear from our 
accumulated observations of the last ten years is_ the 
surprisingly small number of organisms that make up the 
bulk of the plankton. Our food from the sea depends in 
great measure ultimately upon some half-dozen species of 
Copepoda and about the same number of Diatoms. 
. W. A. HERDMAN. 
VisHerRiES LABORATORY, 
UNIVERSITY OF LIVERPOOL, 
March 19th, 1918. 
