comes very great. The increase in the gain, that is shown, is not 
quite regular especially in the later years. This is partly due to the 
difficulty of measuring the length of the old fish accurately enough, 
for a very small mistake in measurement makes a big mistake in 
the calculated weight. We can, however, depend upon the general 
Zz 
Gain in weight in ounces. 
Years of Life. 
Fic. 13.—The yearly gain in weight in ounces for different regions. 
increase in gain shown being substantially accurate. We may con- 
clude that the older the plaice gets the more valuable it is as a 
machine for converting animals like the sand dollar and sea urchin 
into food suitable for man. 
DEATH RATE. 
During the first year while the fish is in the egg and fry stages, 
the death rate must be very high, so high indeed in the bay of Fundy 
and Passamaquoddy bay that apparently not a single egg hatches 
out. Because of the small number of old fish in this region very few 
eggs are to be found and of these none seem to reach the last stage 
previous to hatching. In the gulf of St. Lawrence on the other hand 
the conditions are more favourable and a high percentage of the 
eggs, which are very abundant, hatch. The fry are likewise 
numerous, but much less so than the eggs, there being one larva to 
10 eggs, certainly no more. The older fry are still fewer in number, 
so that only a fraction of the young spawned each year ever change 
into the adult form and reach the bottom. We will consider the 
death rate of the adult fish in connection with our discussion of the 
stock. 
26 
