REPORT OF THE COMMISSIONER OF FISHERIES. 19 
As the egg collections were not equal to the available hatching 
facilities, the shortage was made up by the transfer of 117,800,000 
eggs to the Detroit hatchery from the collecting field in Lake Erie, 
near Monroe, Mich. An assignment of 6,000,000 was deducted from 
the stock on hand for shipment to the Wisconsin Fish Commission 
and 49,280,000 eggs failed to develop. On reaching the eyed stage 
the 162,000,000 constituting the remainder were subdivided, 70,000,000 
being retained at Detroit, and the remainder forwarded to the auxil- 
iary hatcheries in northern Michigan, to be hatched in connection 
with the lake-trout eggs elsewhere referred to. 
Pike-perch egg collections in Michigan waters were confined to the 
field off Bay City, in Saginaw Bay, the work extending over the 
last half of April and yielding 102,600,000 eggs. Of these 20,000,000 
were shipped green to the Duluth hatchery and 12,500,000 fry were 
hatched and planted in various waters in the State. 
_ The whitefish propagation in Lake Erie was satisfactory. A 
scarcity of fish occurred in the Put-in Bay field, and there was a 
shortage in the catch at Monroe Piers, owing to the destruction of 
some of the fishermen’s nets by floating fields of ice at the height of 
the spawning season. The take of eggs in all other fields in this 
lake was greater than ever before, and the yield from some of them 
was twice that of the preceding year. While the aggregate egg col- 
lections, amounting to 479,290,000, were nearly 10,000,000 less than 
in 1914, their quality was so good that there was a decided increase 
in the whitefish output of the Put-in Bay station. The superior 
quality of the eggs is attributed partly to the supervision of the 
operations of the commercial fishermen by the Michigan fish wardens, 
who were constantly on the grounds during the spawning season, and 
partly to a change in the method of handling unripe fish. Hereto- 
fore it lias been customary to hold large numbers of immature white- 
fish in pens on the spawning grounds for the ripening of their eggs, 
and it has been noted that a considerable per cent of the fish so held 
became affected by a condition known as “ plugging,” whereby no 
eggs were secured from them. This year it was determined to place 
no fish in the pens until they were nearly ready to spawn, and the 
results of this change in method were clearly apparent, the eggs not 
only being of a finer grade but the average yield per fish being larger 
than under the old system. The output from the Put-in Bay station 
included shipments of green and eyed eggs to the number of 235,- 
700,000 and the liberation of 209,000,000 vigorous fry in the waters of 
Lake Erie. 
Incidental to the whitefish operations 6,930,000 lake herring eggs. 
were taken and hatched, the output of fry numbering 3,400,000. 
Notwithstanding the fairly good results obtained with the pike 
perch in Lake Erie, as regards both quality of eggs and number 
secured, the collecting period was the shortest every known in Lake 
Erie. Weather conditions in the early spring were all that could be 
desired, thus permitting of the installation of fishing and spawn- 
taking apparatus in advance of the season; and while brood fish 
appeared in plentiful numbers near the beginning of April, none in 
spawning condition were taken until the middle of the month. Be- 
tween that time and the end of the season, which lasted 15 days, eggs 
to the number of 511,715,000 were taken, the majority being obtained 
