Howard. — Glochidia Infection on River Herring 95 



At the time I visited Lake Pepin, August 5th to 

 8th, herring were being taken each day, averaging 

 only about a dozen per day. Wagner in his report on ob- 

 servations made in 1904 upon the fishes of Lake Pepin 

 (Wagner, 1908) calls this species exceedingly abundant 

 at that time. My Nyhart told me that he had not seen 

 many for over five years. They are of no known com- 

 mercial value, so ordinarily are allowed to escape. 



The method of capture was somewhat unusual. Mr. 

 Zack Nyhart operates here a three thousand foot seine 

 of large, (3 inch) mesh in which the principal catch 

 seemed to be buffalo-fish, German carp, pickerel, paddle- 

 fish, and sheepshead. As the large seine approaches the 

 shore the "propagation crew" of the Bureau of Fisheries 

 extends a 200-yard seine around it, thus capturing a 

 number of game fish which escape through the large net 

 when the area enclosed becomes restricted. Ordinarily 

 the U. S. Fisheries crew hold their catch impounded tem- 

 porarily in their seine and infect the fish in lots appropri- 

 ate to the size of their infecting tank, a container of gal- 

 vanized steel with a capacity of 3% barrels. 



For this experiment the herring were transferred by 

 hand or dip-net to the tank and taken, with the least pos- 

 sible delay, in a gasoline launch to the pound. During 

 this run, which took 5 minutes, infection was carried on, 

 the glochidia having been put into the tank prior to the 

 introduction of the fish. In the first attempted infection 

 and transfer, all the fish, thirteen in number, were trans- 

 ported at one time. As it required several minutes to 

 separate the herring from the other fish, those first in- 

 troduced were subjected to a much longer confinement 

 than the last. In this case out of 13 carried, only 4 were 

 alive at the end of the run. In the second attempt a total 

 of 14 were carried in three trips instead of one, with 

 much better results, the total mortality being only 4. 

 In all the runs the tank was kept covered, on the 

 suggestion of Mr. Canfield, to keep out the light and to 

 reduce the factor of fright. I have not, myself, had an 



