the latter, so remarkable is the effect of cold water as compared 
with warm water on the growth of this fish. 
It is possible not only to tell the age of a fish from the scales, 
but also to calculate approximately the amount of growth in each 
year of its life. We first find out the correspondence in rate of 
growth between the scale and the whole fish by getting the average 
size of the scale in fish of different lengths. Then on measuring 
the distances between successive winter points on the scale we can 
calculate the amount of growth in length of the fish for correspond- 
ing years. This also gives us the length of the fish at each year of 
its age. 
In this way we have found out that in Passamaquoddy bay with 
a temperature at the bottom as high as 50° F. in the late summer 
the plaice reaches a marketable size (12 inches) in from three to five 
years, in the open bay of Fundy with a temperature as high as 
46° F. in from four to six years, in Chedabucto bay (temperature 
probably up to 38° F.) in from six to nine years, in the gulf of St. 
Lawrence about halfway between Cheticamp and the Magdalen 
islands with a temperature not above 35° F. in from eight to eleven 
years, and in the Bay of Islands, Newfoundland, where the tem- 
perature never seems to go above 32° F., no marketable fish were 
found, but the rate of growth shown by the small fish captured 
would mean that from 10 to 13 years would be required to produce 
marketable fish. 
Figure 12 shows the average growth of the plaice in each of these 
waters, the successive years in the life of a fish being marked off 
at the bottom of the figure and the height to which the heavy line 
for each locality rises for each year showing the average length 
reached at that age. To what this amounts in inches is shown on 
the right side and in centimetres on the left. The steeper the rise 
in the line the more rapid is the growth. The growth is most 
rapid in Passamaquoddy bay, where a length of 15 inches may be 
reached in less than five years. The slowest growth takes place 
in the Bay of Islands, where the plaice are little more than five 
inches long at the end of the same length of time. Temperature is 
therefore a most important factor in the growth of these fishes. 
The important thing, however, is the production of marketable 
fish of large size. Neither the very warm nor the very cold water 
are best from this standpoint, for in Passamaquoddy bay, although 
23 
