462 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [36] 
I therefore consider it probable that the spawning period of the 
salmon of the second curve (length, without tail, 680 to 790 millimeters) 
is for the majority three and for the minority four years later, and with 
the salmon of the third curve (from 791 millimeters on), four, five, and 
six years later than the spawning period of the St. Jacob’s salmon, to 
determine the age of which I feel utterly incompetent. On the other 
hand, it seems strange that everything comes to an abrupt close with 
this powerful third curvé and its steep slopes. Females of exception- 
ally heavy weight, weighing more than 12 kilograms (during the spawn- 
ing period), are very rare. I consider this as a proof of the truth of the 
assertion that the salmon fisheries certainly interfere with the keeping 
up of the species. J believe that but very few of those female salmon 
which have not gone through a spawning period as St. Jacob’s salmon 
spawn three times during their lives. The circumstance that most fish 
do not participate in every spawning period to which their age would en- 
title them is perhaps the only cause which has saved the salmon fisheries in 
the Rhine from complete decadence, and which has kept the average 
weight of the Basel Rhine salmon at about 8 kilograms. 
In reviewing this whole subject [ feel compelled to warn people not 
to apply the experiences gained in other rivers to the Rhine salmon, and 
vice versa. Among many imported river salmon (with empty intestines) 
which I had occasion to observe in the course of many years, and which, 
according to Mr. Glaser’s statement, came partly from the Oder and 
partly from the Elbe, the fish of the second curve were decidedly in the 
majority ; and this could hardly have been brought about by the char- 
acter of the orders for these fish. The Swedish salmon, on the other 
hand, were very much mixed, and among them I found more exception- 
ally large fish, weighing 16 to 21 kilograms, than among any other kind. 
The habits of migration, therefore, seem to vary in the different rivers, 
perhaps according to the length of the route traveled and the extent 
of distribution in the sea within which certain kinds are found. 
From what is known relative to the salmon fisheries of Scotland and 
Norway, the habits of life of the fish, even, seem to vary. Very prob- 
ably the flesh does in all cases furnish building material for the ovarium, 
but doubtless in greatly varying degree. 
WINTER SALMON. 
After the curves, showing the length of the fish, have led us to the 
view that the conditions of migration of the Rhine salmon can show 
various exceptions from the general rule (supposing, of course, that any 
such rule can be laid down), we shall feel justified in using this cireum- 
stance in explanation of various striking phenomena. The appearance 
of the so-called winter salmon has always been considered as a mys- 
terious problem in the biology of the salmon. These winter salmon 
immigrate from the sea simultaneously with the last spawning salmon, 
from September on, in small numbers (Dutch market reports), and from 
