72 REPOKT OF COMMISSIONER OF FISH AND FISHERIES. 



Manchester Station, Iowa (R. S. Johnson, Superintendent). 



The construction work in progi*ess at the close of the year was com- 

 pleted during the summer and a considerable number of improvements 

 were made by the station force, the most important being the con- 

 struction of a frame building, 14 by 21 feet, to be used as a fuel-shed 

 and store-room. The roadways around the 80-foot ponds were graded 

 and gi-aveled, atnd the land behind the stone protection-wall from the 

 upper spring reservoir was filled in and graded: the walls of the 

 kitchen, mess-house, boiler-house, office, reception-hall, and stairway 

 in the hatchery building were given a coat of paint, and all of the 

 hatching apparatus was thoroughly overhauled and repaired; the 

 rearing-ponds, which were damaged bj' frost during the winter, were 

 torn out and rebuilt, and considerable repairing was done to the stone 

 protect ion- wall and dam, which had been injured by the ice-gorge. 



Fish-cultural operations were conducted on the same lines as in the 

 previous year, j^onds Y, Z, and V being used for the propagation of 

 large-mouth black bass and rock bass. The propagation of crappie 

 was abandoned, as they do not do well at the station, and it is possible 

 to collect large numbers at small expense from overflowed lands at 

 the substation at Bellevue. 



In the summer and fall of 1899 a very peculiar disease appeared 

 among the adult and 2-year-old brook trout in the 80-foot ponds, 

 which resulted in the almost total loss of the younger fish and a large 

 numlDcr of the adults. It first appeared among a lot of 2-year-old 

 fish during the summer and gradually spread until late in the fall, 

 the greatest loss occurring just before and during the spawning sea- 

 son. The s^Tnptoms varied greath', some of the fish being attacked 

 with inflammation of the gills, some with a slimy skin disease, some 

 with tumorous sores, while many died without any outward sign to 

 indicate the trouble. The majority that died, though, were affected 

 with the sores, which seemed to originate from some internal cause, 

 first appearing as a knotty substance under the skin and gradually 

 enlarging and breaking out in a running sore. The sores were not 

 confined to any particular part of the fish, but were distributed over 

 the entire body, sometimes appearing on the head and back, and at 

 other times on the aMomen and tail. The development of the disease 

 was rapid, death taking place two or three days after it appeared. 

 When the epidemic began every effort was made to check it by the 

 liberal use of salt and clay baths, a change of food, and the trans- 

 ferring of the diseased fish to isolated ponds, but all remedies proved 

 unavailing, and it continued until all the brook trout at the station 

 were more or less affected. 



It is questionable whether the disease was infectious, for, while it 

 spread to all of the ponds, they all have independent water supplies 

 and drains, none of the water being used more than once. In addi- 

 tion to chis, the rainbow trout, confined in the same kind of ponds 



