638 U. §. BUREAU OF FISHERIES 
commercial value in Alaska, each species presenting a Series of problems dis- 
tinct from all the others. Furthermore, each of the almost innumerable streams 
of Alaska has, for each of these five species, its individual colony of spawning 
fish, which must have independent protection. The fishery is based exclusively 
on the spawning run, on the fish which, at maturity, are seeking their native 
stream for purposes of propagation; and it is obvious that the future of each 
stream depends on there being provided, each year, an adequate spawning 
escapement from the membership of its own colony. Regulations must be 
devised and enforced, which will so hold the fishing in check that enough of 
the salmon bound for each stream may escape the nets, to Serve as parents for 
a future generation. Failure to accomplish this for any year will make serious 
inroads on the salmon supply when the inadequate progeny of that year shall 
have matured and themselves comprise the spawning run of the year. 
It must be remembered that when these administrative problems were 
imposed on the Bureau of Fisheries a very extensive fishery was already 
established. Millions of dollars were invested, many thousands of men de- 
pended on it for their livelihood, and the products of the fishery formed an 
important food supply for domestic consumption and in foreign commerce. 
This industry had developed in entire indifference to the future. With each 
year all the salmon were caught that could be caught to commercial advantage, 
with no concern as to the size of spawning reserves. The inevitable conse- 
quence had been partial depletion, in varying degree, throughout the coasts 
and streams of Alaska. ‘The damage already done involved not only the current 
year. Salmon of the different species mature at different ages, from 2 to 7 
years, and the progeny of the inadequate brood years of the past were already 
in existence and must form our sole dependence for salmon runs extending 
over a term of years. 
Had it been feasible to abolish the industry out of hand, increased spawn- 
ing of all species in every stream would have resulted immediately, and rapid 
improvement could have been predicted confidently. But nothing approaching 
this simple solution was possible. A gradual curtailment of fishery operations 
was all that could be hoped for, which would occasion as little harm as possible 
to the fishery and at the same time insure progressively larger spawning 
reserves. It was a new experiment in fisheries conservation, the exact results 
of which could not be foretold. Regulations to. insure the desired result called 
for the establishment of a delicate balance between commercial catch and 
spawning reserve. The effect of the regulations must be made the subject of 
careful analysis in each district, and modifications made from year to year, as 
experience should dictate. The pressure of this responsibility has been so 
great that Commissioner O’Malley has felt constrained to take the field each 
year in person, and has found full scope for his intimate knowledge of the 
Alaska situation and his wide practical experience of the fisheries. | 
As Doctor Rich has pointed out, the scientific staff of the bureau fortunately 
had made substantial progress in working out the life histories of the salmon 
before these heavy responsibilities devolved upon the bureau. <A firm basis 
for conservation measures was thus at hand. But with the assumption of new 
duties toward the salmon, the demand for increased knowledge was at once 
experienced, and some of the unexplored regions took on a sudden and pressing 
importance. Among these unsolved problems, and the most urgent of them, 
was the question of how large a spawning reserve could be considered ade- 
quate in any stream, or, stated in different form, how large a yield can normally 
be expected from any given number of spawning fish. No even approximate 
answer to this problem was at hand, and yet the bureau found itself suddenly 
confronted with the duty of providing an ‘ adequate spawning reserve” in 
each of the streams of Alaska. It is to throw light on this all-important subject 
that the Karluk and Chignik experiments have been devised. 
The urgent necessity for this investigation had been appreciated even prior 
to 1924, and a beginning had been made before that date. The difficulties of 
the problem were seen clearly. The normal or average yield from a given 
number of spawning salmon could be expected to vary more or less widely 
for the same species in different streams, and would surely vary extensively 
for different species even in the same stream. Furthermore, a certain amount 
of variation could be anticipated between one year and another for the same 
species in the same stream. 
The final yield from a given number of spawning fish would depend on 
percentage of successful spawning, percentage of escape from destructive 
physical agencies, from diseases, and from predatory enemies; and these, with 
