THE WHITEFISH PRODUCTION OF THE GREAT LAKES. 675 
TABLE 17a.—SHOWING THE RELATION BETWEEN THE AVERAGE PLANT OF WHITEFISH FRY PER SQUARE 
MILE PER PERIOD AND PER POUND CAUGHT PER PERIOD TO THE AVERAGE PERCENTAGE OF INCREASE 
OR DECREASE IN THE CATCH OF EACH PERIOD OVER THE PRECEDING PERIOD. 
Average per- 
centage of in- 
Average plant | Average plant eters: (+) or 
per square per pound Baar s = 
Whitefish areas. mile per area caught per aeyok s 
for five-vear | area for five- 2 presen 
| periods. year periods. isos a866) 
and of period 3 
over period 2. 
Miamninteciatinlti Tan MOVE << ierinicta nom oan eee ce eee e on 
I [ike nie CANAAN) tam ao ene 28, 000 96 4472.0 
Lake Michigan (southeast shore 
Lake Michigan (north shore) _ 
2 {rake Huron (west shore) - -_- a 10,000 32 + 0.7 
Lake Superior (south shore) _--_-________-_ cll 
Peake Ontaria (Northshore) 2). - |= 223 eo anne ene a ane cae 
ace RA INEES TE VEE SE SCE) Os Se ce oe ee Sn ee ee cape 
3 |\Lake Superior (north Shore) =e) xr 26.0 
CH ALESP ALD: SPLVTE TR sp ee SS a ee p= ey 
@If we exclude Lake Michigan, southeast shore, on account of the phenomenal increase of 350 per cent inthe third 
period, this value becomes +31, but there appears to be no valid reason for such exclusion. 
In table 17a is shown the relation of the average intensity of plant of 
each of the-three groups of areas to the average catch in the same areas. ‘The 
first Column contains the average of the plant for the areas of each group for the 
three periods expressed in fry per square mile and the second column contains a 
like average expressed in fry per pound of whitefish caught. Thus the value 
28,000 in the first column of table 17a is obtained by adding all the numbers 
in the first column of table 17 opposite the areas of the first group and dividing 
the sum by 9, and the remaining values in columns one and two of table 17a 
are obtained in like manner. The percentages in the third column of table 
17a are obtained by adding for each group of areas the percentages given in 
the third column of table 17 and dividing by 6 in the case of groups 1 and 2 
and by 8 in the case of group 3. 
It thus appears that, on the average, a plant of approximately 30,000 per 
square mile of whitefish area or of 100 per pound of whitefish caught is cor- 
related, under existing conditions, with an increase of 72 percent inthe catch; a 
plant of 10,000 and 32 with a practically stationary whitefish product; a plant 
of 2,200 and 11 with a decrease of 26 per cent in the whitefish product. This 
appears to the writer to amount to a mathematical demonstration of the 
efficacy of the planting of whitefish and to afford a measure of the intensity of 
plant necessary. This measure applies, of course, to present conditions; as the 
whitefish production increases it is possible that a plant of less than 100 per 
pound will suffice to maintain the fisheries. 
In table 22 is given the total plant and catch for the Great Lakes and from 
this appears the average intensity of plant for 1903, the last year for which data 
are available for the catch. The intensity of the plant per pound caught is here 
