SEA-FISHERIES LABORATORY. PUM | 
be economised. The fish were therefore trawled only 
when they were abundant. Small experiments were 
made—10 to 75 fish as a rule—and the marked fish were 
at once liberated. Occasionally the fish had to be 
marked on a passage from-the fishing ground to some 
other place, and it happens therefore that they were not 
always liberated on the ground where they were 
captured: JI have mentioned the experiments where 
this was the case. Later on much larger experiments 
were made, and from 100 to 150 plaice were marked on 
the same day, the vessel ‘‘ standing by’’ the fishing 
ground till the fish were liberated. On two occasions the 
fish were caught in stake nets and taken alive to the 
laboratory at Piel. They were then marked, and after 
remaining for some hours in the tanks were taken out 
to sea and liberated in the neighbourhood of the place 
of capture. When the fish were trawled a beam trawl of 
30 feet beam, and with a net of 6-inch mesh, was used, 
and short hauls—3? to 1 hour—were made. In all future 
work it will be advisable to make large experiments, and 
to liberate at least 250 fish in the course of each. The 
other procedure need not, however, be different from 
that described above. 
Some defects inherent in the methods adopted may 
be mentioned, and some criticisms noted. The _ brass 
label and the bone button are both liable to corrosion; 
the former because of electrolytic action, the brass being 
electro-negative to the silver wire, and the latter 
apparently because of the solvent action of the CO, in 
the sea-water. The result of this is that after about two 
years the numbers on the brass label may become 
illegible; while the hole in the bone button may enlarge 
so that the latter drops over the looped wire. The wire 
and label may then work their way out from the wound. 
