646 U. S. BUREAU OF FISHERIES 
ered, and additional returns from some of the experiments are to be expected 
during future years. 
The collection of the data from the returning adults has proved to be a difii- 
cult matter. Some representative of the Bureau of Fisheries has spent the 
greater part of each season in the commercial fishing district, but it has been 
necessary to depend, for the greater part, upon the assistance of fishermen, can- 
nery employees, and hatchery men for these data. The majority of the returns 
have come as a result of the payment of rewards for records of recoveries. 
Two species of salmon have been marked—the chinook salmon (Oncorhynchus 
tschawytscha) and the sockeye salmon (Oncorhynchus nerka). The experi- 
ments with sockeye salmon will be considered first. 
A thorough understanding of the sockeye marking experiments will require 
a knowledge of the history of the Columbia River fishery for Oncorhynchus 
nerka, which is known there as “blueback salmon.”** In the early years of 
the fishery this species contributed an important part of the pack. For the five 
years, 1890 to 1894, it supplied an average of 43,000 cases. With the exception 
of a large pack in 1898, there was a rapid decline until the low level of less 
than 6,000 cases was reached in 1907. For the five years, 1904 to 1908, the 
average pack was about 9,000 cases—less than one-fifth of that of the period 
15 years earlier. 
In 1905 the Oregon Fish Commission made an effort to rebuild the run by 
artificial propagation and built a hatchery for that purpose on the Wallowa 
River. For some unknown reason, no bluebacks were intercepted by the racks 
at that station. Having failed in this undertaking, and knowing of no other 
tributary in which spawning bluebacks might be found, the Oregon Fish Com- 
mission called upon outside sources for a stock of eggs. In 1910 they received 
a shipment of 1,500,000 sockeye eggs from Alaska. Similar shipments of 
Alaska sockeye eggs were obtained each following year. 
In the years in which the imported sockeyes should have reached maturity, 
none entered the tributaries in which they had been liberated, and there was 
some question as to the success of their propagation. It was suggested by some 
that the fish had returned to the Columbia River but not to the particular 
tributaries in which they had been liberated, the supposition being that in this 
case they would have been mistaken for native bluebacks. Other persons, who 
were not convinced of the truth of the “ parent stream” theory, suggested that 
the fish might have entered some other river system for spawning. 
The marking experiments with sockeye salmon were undertaken primarily 
to determine these points. The first experiment consisted of a marking of 
50,000 yearlings, which were liberated in a tributary of the Columbia River 
in March, 1916. Adult fish from this experiment returned to the Columbia in 
1918 and 1919, when they were in their fourth and fifth years. Authentic 
records of about 100 of them were reported from the commercial fishery. This 
number is of little significance, however, as no rewards were offered at that 
time, and as a result the reported returns are known to have represented only 
a small part of the actual recoveries. 
The most interesting fact coming from this experiment was that these Alaska 
sockeyes differ sufficiently from the native bluebacks as to make it possible 
to distinguish the two classes of fish from each other by appearance only. This 
suggested the question of why these fish had not been observed in the Columbia 
River during the preceding four years when results of the propagation of the 
sockeyes should have been obtained. The only logical answer to this question 
was that the propagation had not been successful. The confidence in this 
answer was strengthened when it was observed that the fingerlings in former 
years had been liberated at a much earlier age. More conclusive evidence was 
obtained by a second marking. In this experiment the marked fingerlings 
were liberated during the fall of their first year, instead of being held until the 
spring of their second year, as in the first experiment. Not one return was 
obtained from this marking. It is evident, then, that under the conditions that 
prevail at these Columbia River hatcheries, success with sockeyes obtains only 
when the fingerlings are held until the spring of their second year—until their 
normal time of seaward migration. 'These results might be presented as 
evidence of the necessity of carefully checking the success of hatchery opera- 
tions. In this instance it has been shown that success does not necessarily 
result from the liberation of large and vigorous fingerlings. 

16 As a matter of convenience, the term ‘ blueback ”’ will be used in referring to the fish 
native to the Columbia River, ‘and the term “sockeye ’’ will be used in speaking of the 
imported fish. Both are of the species Oncorhynchus nerka, 
