PEOPAGATIOISr AND DISTRIBUTIOX OF FOOD FISHES, 192 8 371 



number of fish bandied was greater. Extensive trout-hatching operations are 

 now conducted at the La Crosse station. Brook-trout and rainbow-trout eggs 

 were obtained from the bureau's stations in Missouri and Iowa and from the 

 Pend Oreille County Fish and Game Commission througli exchange. A number 

 of Loch Leven-trout eggs also were incubated, but the fry suffered a rather 

 heavy mortality. The demand for this species in Wisconsin and Minnesota 

 appears to be increasing. The Lincoln Park Aquarium at Chicago incubated 

 a number of rainbow-trout eggs, the fry from which were distributed under the 

 direction of the La Crosse station. Inasmuch as the capacity of the La Crosse 

 station is insufficient to handle the full number of fish needed, the surplus is 

 transferred to the substation at La Crosse and to the Lynxville auxiliary pend- 

 ing distribution. 



Much of the time of the La Crosse station personnel is taken up in adminis- 

 tering the many cooperative nurseries in that territry. Thirty-nine nursery 

 projects, having a total of 49 ponds or tanks, are now in operation under the 

 bureau's direction in Minnesota and Wisconsin. The rescue operations were 

 very successful. In the upper Mississippi River field 145,176,900 fish were 

 handled. The usual small percentage, amounting to four-tenths of 1 per cent, 

 was distributed to other waters on application. The rest of the fish were re- 

 turned to parental waters. The cost of the work amounted to approximately 

 $0.12G per thousand fish rescued. Certain areas formerly handled by the 

 bureau were covered by the States of Wisconsin and Iowa. _ In connection with 

 the rescue work, almost 2.000,000.000 larval mussels were released in the 

 parasitic stage on rescued fish. The aggregate number of trovit hatched was 

 over 1,500.000. 



Homer (Mmn.) siidstrition. — The construction of new boats and equipment 

 and the overhauling of engines, machinery, boats, and trucks were the im- 

 portant features of the work at this substation. Fish-cultural operations 

 are confined to rescue work, as the water supply is unsatisfactory and inade- 

 (.[uate for the successful hatching of eggs. This work is limited, however, and 

 the station is used chiefly as headquarters for construction and repair work 

 on boats and as a center for work in the upper Mississippi River wild life 

 refuge. It is planned to build propagating ponds in the refuge, and then the 

 location of the Homer substation will make it the logical headquarters for 

 the supervision of that work. 



Marquette (Iowa) suhstation. — During the year this substation rescued 

 more than 50.000,000 fish, the territory covered including areas around Gut- 

 tenberg and Buena Vista, Iowa. Mussel-infection work also was carried on. 



Bellevue (Iowa) suhstation. — In addition to the usual rescue work eggs of 

 the bufiialo fish and carp were collected, fertilized, and planted, and some mus- 

 sel-infection work was done. 



Lifii.rviUc (Wis:) substatioji. — Ten galvanized-iron holding tanks, capable of 

 holding about three carloads of fish, were added to the equipment of this sta- 

 tion. These will be of material assistance to the distribution work during 

 periods of low water. Electric-light lines also were installed. The work at 

 this substation consists chiefly of rescuing the commercial species and the 

 catfish. It also collects mussels and sends them to the field crews for in- 

 fection. During April, May. and June surplus trout from the La Crosse sta- 

 tion were handled at Lynxville. The results of this work are described in 

 the section of this report dealing with the La Crosse station. 



MussBX Infection 



[Conducted by the Pairport (Iowa) and La Crosse (Wis.) stations in conjunction witli the 



rescue of landlocked fishes] 



The customary work of infecting rescued fishes with the larvae obtained 

 from gravid mussels of the commercial varieties was continued. At La 

 Crosse 1.915.485,750 glochidia of various species were i-eleased on fishes, while 

 at the Fairport biological station 139,069.400 young mussels were planted in 

 connection with the rescue of 2,405,194 fishes and the hatching of over 80.000. 

 This large number of larvae was handled at a cost ranging at from a little 

 over 1^2 to 4314 cents per thousand, depending upon the location of the work. 

 The total output surpassed that of the previous year, though it did not reach 

 that of some of the earlier years. 



