THE WHITEFISH PRODUCTION OF THE GREAT LAKES. 661 
in Michigan has been taken directly from the original records on file in the office 
of the Michigan Fish Commission, while the catch in Canadian waters has been 
kindly furnished by the Department of Marine and Fisheries of the Dominion 
of Canada. The plants of whitefish that have been made in Canadian and Michi- 
gan waters have been taken from the reports of the Department of Marine and 
Fisheries of the Dominion of Canada, from the reports of the United States Fish 
Commission, and from the reports of the Michigan Fish Commission. In the 
column headed “‘ Total gill and pound nets in fathoms” are given in fathoms the 
added lengths of gill nets and of pound-net leaders. The lengths of gill nets are 
given in fathoms in the official records. The lengths of pound nets are also given 
in fathoms in the Michigan records, but in the Canadian records the number only 
of pound nets is given, without theirlengths. In order to obtain the lengths of 
pound nets used in Canadian waters I have averaged the lengths of approxi- 
mately 1,000 Michigan pound nets selected at random, and have multiplied the 
number of Canadian pound nets in each year by this average value. In the last 
column of the tables 1 to 10 are given the values obtained by dividing the total 
catch of whitefish in pounds by the lengths of gill nets and pound nets in 
fathoms. ‘The figures in this column therefore express in pounds for each year 
the catch of whitefish per fathom of nets used. It should be understood, how- 
ever, that these tables give the total lengths of all gill and pounds nets used in the 
waters referred to whether the nets actually took whitefish or not. I have 
found it impossible to separate the nets which were set for whitefish or which 
took whitefish from those which were set for other fish, and I have been there- 
fore under the necessity of taking the total lengths of all gill and pound nets 
used in the waters under discussion. As will appear in the discussion which 
follows, I attach relatively little importance to this part of the table. 
I have already alluded to the difficulty encountered in obtaining statistics 
which deal with whitefish only and which do not include at the same time 
longjaws, bluefins, or menominees. We are assured by the superintendent of 
the Michigan Fish Commission that the data for the catch of whitefish in Michigan 
waters contained in tables 1 to 10 include true whitefish (Coregonus clupetformis) 
only, and I am assured that the statistics of the catch of whitefish collected by 
the authorities of the Dominion of Canada and included in tables 1 to 10 refer 
to the true whitefish only and do not include bluefins or longjaws. These tables 
therefore have a peculiar interest in being, so far as I know, the only tables 
published of the catch of true whitefish for a continuous period of fifteen years. 
