REPORT OF COMMISSIONER OF FISH AND FISHERIES. LXXIX 



Marsh was detailed from November 14 to 27 to investigate the disease, 

 and on his return to Washington, Dr. 0. M. Blackford was sent to 

 continue the investigation, remaining in Northville from December 5 to 

 January 14. The affection was apparently traced to bacteria, supposed 

 to have been caused by the rotting timbers of which the ponds were 

 constructed. From experiments conducted at the station it would 

 appear that even where an epidemic of this character prevails, if the fish 

 can be transfeired to open waters and allowed to subsist on natural 

 food the mortality will at once cease. On June 9, 5,000 brook-trout 

 fry, which had been fed for several months in the rearing-troughs and 

 were from 2^ to 3 inches long, were placed in the spring pond, where 

 they received only the natural food contained in the spring water. 

 After remaining there for some time they began to assume a different 

 color from those fed on liver, their tails and fins becoming very brilliant 

 and presenting a beautiful appearance. Not over half a dozen dead 

 ones were taken from the spring from the time they were introduced 

 to September 30, yet when counted on that date there were only 3,400, 

 the loss being attributed to kingfishers and destructive animals. 



The Loch Leven brood trout were quite old and yielded onlj^ 14,500 

 eggs, all of which were shipi)ed to Prof. William A. Locy, of the North- 

 western University, Evanstoii, 111., and to the Connecticut Fish and 

 Game Commission. On June 30 there were 107 Loch Leven trout of the 

 hatch of 1895, 1,404 of 1897, and 2,308 of 1898. The fish of 1897 will 

 probably yield a considerable number of eggs during the coming fall. 



Of the steelhead trout on hand at the beginning of the year, 2,500 

 were planted in September in streams along the line of the Flint and 

 Pere Marquette Kailroad. At the close of the year there remained on 

 hand 607 of the hatch of 1897 and 3,549 of the hatcli of 1898. A case 

 of eggs was received from Oregon in June, but unusually warm weather 

 en route caused almost a total loss. The 5,000 fry hatched from them 

 were doing well at the close of the year. 



On February 2, 16,500 rainbow-trout eggs were received from Neosho; 

 these yielded 13,000 fry, which were distributed during the spring. 



On the 6th of June 67,360 grayling eggs were received from Elk 

 Creek, Montana. Though the weather was very warm, the condition 

 of the eggs on arrival was excellent, the temperature of the top tray 

 being 55° and the middle of the case 60^. They were hatched on open 

 trays in shallow troughs. A few of the fry came out immediately after 

 being unpacked, and by June 13 they were all hatched, but it was noted 

 that the fry remained at the bottom of the trough for several days 

 before attempting to swim. The fry from Michigan grayling, handled 

 at Northville fifteen years ago, commenced to swim as soon as hatched, 

 and were much larger and stronger than these. Of the 55,000 result- 

 ing from the shipment, 50,000 were planted in the Au Sable and Pere 

 Marquette rivers. The balance were retained for observation and 

 experiment, and at the close of the year they were doing well, apparently 

 taking food as ireely as the trout. 



