PROGRESS IN BIOLOGICAL INQUIRIES, 1926 535 
are wholly unprotected and appear to be abundant in Lake Huron, 
each year the fishery is being prosecuted with increased vigor, for as 
the abundance of the more desirable species of coregonines decreases, 
the demand for the herring increases. It is evident from the bio- 
logical data, however, that in all probability the herring can not 
withstand further exploitation without disastrous results. The re- 
sults of this investigation are given in greater detail on p. 662 of this 
report. 
Whitefish material has been collected by Doctor Van Osten from. 
Lake Huron every year since 1923. These data indicate that the 
whitefish taken by gill nets in summer are younger than those taken 
in the fall. The summer catch consists principally of 4-year-old 
fish, a large percentage of which is sexually immature though of legal 
size. The fall catch consists mostly of 6-year-old fish, the 7-year-old 
individuals being second in abundance. ‘The youngest fish taken in. 
these samples were in the fourth year of life, the oldest in the 
thirteenth. Most of the fish of a year class probably do not spawn 
until the sixth year of life. Ths result was unsuspected, as it is 
generally believed that the whitefish attains sexual maturity in its. 
third year. There is some evidence, however, that this is true in 
the case of the Lake Erie whitefish. 
SURVEY OF SANDUSKY BAY IN LAKE ERIE 
In response to an appeal from the Izaak Walton League at Fre-. 
mont, Ohio, a preliminary survey was made of conditions in the San- 
dusky Bay region, with special reference to the destructiveness of 
commercial nets (especially the seines) to game fish. All complaints. 
were considered and investigated. It was concluded that the commer- 
cial fishermen of the Sandusky Bay region were not as destructive of 
fish life in general, or of strictly game fish in particular, as many 
sportsmen alleged. On the contrary, it appeared very probable that 
the seiners, by capturing carp and goldfish, were aiding in preserving 
conditions necessary for the existence of game fish and waterfowl. 
BIOLOGICAL SURVEY OF THE UPPER MISSISSIPPI RIVER 
In July, 1926, A. H. Wiebe was assigned to make a biological 
survey of the upper Mississippi River. The object of this survey 
was to determine if the pollution from the cities of Minneapolis. 
and St. Paul is destroying life in the Mississippi River. The part 
of the river covered by this survey extends from just above Minne- 
apolis to just above Winona, about 110 miles below St. Paul. 
The field work was carried on during August and September. After 
the completion of the field work (September 30) the plankton and 
the bottom samples were moved to the University of Wisconsin, at 
Madison, for study. The samples were analyzed and a report was 
prepared. 
The investigation showed that pollution from the Twin Cities is a 
factor in the destruction of life in the Mississippi River from Minne- 
apolis down to Red Wing, at the head of Lake Pepin, as is shown 
in more detail on p. 669. 
