bucto bay, 20 inches; gulf of St. Lawrence, 24 inches. These figures 
refer only to the lots that we have just considered and probably 
represent the average condition that would be found on examina- 
tion. Occasionally one is sure to find still larger individuals. We 
have reached in this study the general result that in the colder 
water the lower death rate more than makes up for the slower 
Ada 
Gulf of St. Lawrence Chedabucto Bay Passamaquoddy Bay 
Age in years 
La 
=) 
Fic. 14.—Relative numbers of the various ages in the stock of plaice in different regions. 
growth in producing large individuals. As to the cause of the 
higher death rate in the warmer water, we can only suppose that 
the rapid, forced growth makes the fish, just as it makes hothouse 
plants, less hardy, and that they therefore succumb more readily 
to disease. We have already seen that they contain more parasites 
than the fish living in colder water. 
THE EFFECT OF FISHING ON THE STOCK. 
If we have a more or less stationary condition of the stock from 
year to year, the loss by death being made up yearly by the fish 
newly spawned, what will be the result of beginning to fish the area? 
Let us suppose that there exists a condition in which the death rate 
is one-seventh of the total population per year and that all fish 
of five years or more in age are suitable for market. In this case, 
which is very similar to what we have found in the gulf of St. 
Lawrence, the marketable stock at the end of each year will have 
the composition shown in figure 15 at the left (‘original condition’). 
30 
