EEPORT OF COMMISSIONER OF FISH AND FISHERIES. 



85 



Fry. — All eggs were liatched in April and the fry were in good condi- 

 tion, except Atlantic salmon, and the parentage of this lot is mentioned 

 under the heading of Green Lake Station. In order to accommodate 

 and successfully care for the young fish in process of rearing, it was 

 necessary to erect, in advance of more permanent constructions, a 

 temporary outdoor stand containing 46 troughs. These, with 38 half 

 hogsheads, arranged at the same point, and the interior troughs of the 

 hatchery, afforded 126 receptacles. The supply conduit, 7,050 feet 

 long, was ventilated by the removal of boards at more than 300 points, 

 and for still more complete aeration 25 breakwaters were inserted. The 

 flow was increased to permit the employment of 15 to 25 gallons of 

 water per minute to each trough and tub. Four temporary ponds, to 

 receive the waste of outdoor receptacles, were among the preparations. 



Supplies of food, consisting principally of liver, were obtained at 

 Bangor instead of Ellsworth at a reduced rate of cost. The older fry 

 began feeding May 12, all others following before the end of the month. 

 The approximate stock of fry May 31, with losses, is given below: 



The only material loss during June was through the instrumentality 

 of a parasite which attacked and destroyed the greater portion of the 

 lake trout and a relatively smaller number of salmon. A report on 

 this subject, by S. G. Worth, contained the following: 



The lake-trout fry iu rearing-troughs, both outdoors and under shelter, were nnder- 

 going a higher rate of mortality than any other species, their bodies being dotted 

 Tvith white spots. It had been found that the treatment with salt, termed "salt- 

 ing," had lowered the death rate, practically ending it, but no solution of the malady 

 was given. My examination showed that the spots on an average were the size of a 

 common fly speck, scattered irregularly over the bodies of the fish, on the foreheads, 

 sides, tail, and fin bases, and even on the extremities of these appendages. The 

 spots were white with a tinge of blue, the blue being due, perhaps, to sky reflection. 

 They were easily removed by a knife blade and came off immediately on contact with 

 cheesecloth hand-net. 



The fish had been feeding i)oorly and at first I thought the spots were pimples 

 resulting from intestinal inflammation — in other words, an eruption. This surmise 

 was strengthened by the limp consistency of the pimples, some of which were 

 pointed at their apexes, the general appearance being that of mucus. Upon detach- 

 ing specimens they had the appearance of clabber (sour milk), and under a pocket 

 glass of low power I found irregular watery markings, occupying, in some specimens, 

 25 per cent of the area. Upon examining them patiently I discovered a movement 

 in one and later in another, and finally seven specimens on the pane of glass, as 

 if recovering from the shock incident to detachment, were all iu motion, circling 

 around at the rate of one-eighth to one-fourth inch per second. Hence I inferred 

 that the spots were animals, parasites, perhaps the larvte of some insect. 



