PROPAGATION AND DISTRIBUTION OF FOOD FISHES, 1923, 57 



MUSSEL INFECTION IN CONJUNCTION WITH THE RESCUE OF LANDLOCKED 



FISHES. 



fH. L. Canfield, in charge.] 



The infection of rescued fishes with the larvae of commercial fresh- 

 water mussels was undertaken on a large scale and resulted in the 

 release of 2,048,977,910 larval mussels (glochidia) in a state of 

 parasitism on the gills of host fishes. This total, representing by 

 far the largest amount of mussel-infection work ever accomplished 

 in a single year, was done at a very considerable reduction in cost 

 as compared with that of the previous year, the average per thou- 

 sand glochidia being only $0.0025. By combining the operations 

 connected with the rescue and the mussel-infection work it has been 

 possible to produce enormous quantities of juvenile mussels at a low 

 cost, and the clam fishermen and others engaged in the industry 

 have cooperated with the bureau to the fullest extent to make the 

 work a success. The following table summarizes the mussel work 

 of the bureau during the fiscal year 1923, showing the fields in which 

 operations were conducted and the numbers and species of mussels 

 handled in each. 



Extent of mussel-proixtf/ation work in 1923, shoiving fields of operation and 

 numbers and species of mussels handled in each. 



Field. 



Grass mucket. 



(Lampsilis 



luteola.) 



River 



mucket. 



(Lampsilis 



ligamentina.) 



Pocket-book.' 

 (Lampsilis 

 ventricosa.) 



Total. 



Minneiska, Minn 



Winona, Minn 



Homer, Minn 



Dakota, Minn_ _, 



La Crosse, Wis 



Brownsville, Minn... 



Genoa, Wis 



Ferryville, Wis 



Lyn.wille, Wis._ 



^iarquette, Iowa 



Guttenberg, Iowa 



Bellevue. Iowa._ 



Rock Island. Ill 



Gordons Ferry, Iowa. 



Number 

 30, 209, 

 70, 060, 

 58, 338, 

 4. 082, 

 61, 853. 

 67, 579, 

 97, 070, 

 63, 800, 



614, 763, 

 13, 600, 

 20, 565, 



255, 635, 

 67, 275, 

 26, 737, 



500 

 000 

 000 

 500 

 750 

 750 

 000 

 000 

 000 

 000 

 000 

 610 

 500 

 000 



Number. 



14, 506, 500 



13, 500, 000 



3, 235, 000 



5, 343, 000 



860, 500 



21, 193, 350 



121, 310, 000 



21, 3.50, 000 



68, 472, 500 



Number. 



1, 798, 300 



36. 000, 500 

 64. 375, 000 



28, 567, 500 

 143, 451, 100 

 35, 201, 550 



18, 243, 500 



Number. 



44, 716, 000 



83. 560, 000 



63, 371, 300 



9, 425, 500 



62, 714, 250 



124, 773, 600 



282, 755, 000 



85,150,000 



683, 235, 500 



13, 600, 000 



49, 132, 500 



417,330,210 



102, 477, 050 



26, 737, 000 



Total -...- I 1,451,569,610 



I 



476, 991, 000 ! 120, 417, 300 



2, 048, 977, 910 



' This mussel is not first class in quality, and fishes are infected with it only when first-class mussels are 

 not available. 



FISHES OF MINOR INTERIOR WATERS. 



Under this general head is included tlie work of the Rocky Moun- 

 tain trout stations, the New England trout and salmon stations, the 

 combination trout and pond fish-cultural stations, and that group 

 of stations devoted exclusively to the production of warm-water pond 

 fishes. The fishes propagated at these stations are, as a rule, dis- 

 tributed to applicants, but considerable numbers, especially of the 

 black-spotted trout, are returned to the ^yaters from which the eggs 

 are derived. Since the advent of the automobile and the extensive 

 opening up of roads in formerly inaccessible regions, many streams 



