6 . U. 8. BUREAU OF FISHERIES. 
activities, vast numbers of eggs would be sent to market in the fish 
and become a total loss. In the case of certain species, notably but 
not exclusively the salmons of the Pacific coast, where commercial 
fishing does not extend to or is not permitted on the spawning 
areas, employees of the bureau capture the spawning fish either in 
seines or in traps and artificially incubate im its hatcheries the eggs 
thus obtained. The object of this work is to bring about a higher 
percentage of fertility in the eggs than is possible in natural repro- 
duction and to afford the eggs and the resulting young fish protection 
from their natural enemies. Eggs in appreciable numbers are also 
obtained from domesticated fish, which are maintained in ponds at 
fish-cultural stations from year to year under more or less artificial 
conditions. 
A decrease of approximately 121,000,000 in the aggregate egg 
collections occurred this season as compared with last year, as is indi- 
cated by the accompanying table, and the same causes that were 
operative to the detriment of the work then were again in evidence. 
However, in any line of enterprise where results are dependent to a 
large extent upon weather conditions, as is the case in all of our ege- 
collecting fields, a comparison of one season’s work with that of 
another will indicate a considerable fluctuation in total results, and 
it is only by comparing the results over a period of years that the 
actual trend of the work may be traced with any degree of accuracy. 
The most noticeable variations in the egg collections of 1921 as 
compared with 1920 are increased collections of eggs of chum salmon, 
cisco, rainbow trout, blackspotted trout, whitefish, “pike perch, yellow 
perch, striped bass, ¢ carp, haddock, and glut herring, and decreased 
collections of eggs of the chinook, silver, sockeye, humpback, and 
steelhead salmon, landlocked salmon, lake and brook trout, shad, 
buffalofish, cod, pollock, and other species of less importance. It is 
to be noted that while a decrease occurred in the number of eggs 
collected during 1921, as compared with the previous year, there was 
an increase of approximately 179,000,000 in the aggregate output of 
the stations in eggs, fry, and _fingerlings. This apparent dis- 
crepancy in fioures i is accounted for by the better quality of the eggs 
handled during the year and the higher percentage of fry produced; 
also to an increase in the numbers of eggs fertilized and planted on 
the spawning grounds. 
COMPARISON OF EaG COLLECTIONS, 1920 AND 1921. 
Ris ost Fiscal year Fiscal year . Fiscal year Fiscal 
Species. 1920 1921. Species, 1920. “192 
Butialoy nish. ccnee: 236, 400, 000 163, 267,000 || Blackspotted trout. . 2, 617, 600 5, 993, 600 
(Of DSoegaeccon causes 47, 250, 000 117, 218, 000 || Loch Leven trout. --. 85, 000 94, 220 
SUiGs Gece ceten cee 65, 667, 000 37, 549, 000 |} Lake trout........... 53, 753) 000 44,247, 500 
Glittering S425. oc |.0sscosce come 55, 130, 000 |} Brook trout......... 19, 947, 900 16, 110, 810 
Milewites a. ctestoneeine = 130; OG0K| nar verse A Se Grayling ae seo cceae 700,000 | .5 cz 2 fentes 
Wihitetishs 2-5 Jecec<- 422,769, 000 5402776" 000)||"SMelt-2:e aso cccocscc|oesonacece aso 8, 000, 000 
CISCO hes maaensoe 181, 150, 000 317, 200, 000 || Pike perch. - 416, 100, 000 508, 942, 000 
Chinook salmon..... 51, 793, 000 43, 829, 820 || Yellow perch . 175, 398, 000 218, 333, 750 
Chum salmon........ 15, 417, 000 28, 182, 000 |) Striped bass 19, 358, 000 24, 600, 000 
Humpback salmon... 579 (3004) dency eens p Cader .+ 912, 417, 000 482,012, 000 
Silver salmon........ 10,079 000 8, 273, 000 |} Haddock... 406, 235, 000 635, 950, 000 
Sockeye salmon...... 108, 115, 000 76,012, 500 || Pollock. .......- 954, 800, 000 650, 850, 090 
Steelhead salmon.... 4,006, 609 1,603, 000 || Winter flounder 1, 805, 167, 000 | 1,980, 291, 000 
Atlantic salmon. .... 797, 600 Oi $207 || POL NOUNGEL- unis. - acl secs nsc cman eee 19. 410, 000 
Landlocked salmon. - 2,026, 800 1,063, 200 
Rainbow trout. ..... 9, 631, 200 10,994) 750 Potals A.J... 6, 121, 390,009 | 5,996, 844, 870 
