PROGRESS IN BIOLOGICAL INQUIRIES, 1926 . 643 
when an unsuccessful spawning occurs, two years thereafter there 
can not be a large run. Sometimes when a successful spawning 
occurs, unfortunately, a large run does not occur two years thereafter. 
It is possible to undo the effects of a large spawning and not possible 
to overdo the effects of a small spawning. 
Mr. Tuomeson. Is it your opinion that the large mortality in 
migrating to sea has in very many cases destroyed those 2-year and 
4-year cycles? Are these cycles not evidence, rather, of the stability 
of that correlation ? 
Doctor Gitpert. So far as that is concerned, I am ignorant at this 
time. The correlation will be between the commercial catch of a 
given year and the returns 4, 5, or 6 years thereafter. The correla- 
tion will have to be between the spawning escapement and the adult 
return. Unfortunately, prior to the present era, we have no statistics 
except those for the commercial catch. It may very well be in a 
given region that the commercial catch has a definite relation to the 
spawning escapement. In Bristol Bay the fishing is conducted ex- 
clusively by gill nets operated from small boats. If the season is 
very stormy the small boats can not operate freely and we will have 
a very much larger percentage of fish escaping than we have in a 
season of good weather in which it will be possible to fish every day. 
You can see that our correlations are based on very inadequate data. 
Doctor Davis. In regard to the marking experiments, we thought 
it would be very desirable to mark the young trout last summer. We 
cut off the fins, etc., and in practically every case within two months 
they had almost grown out again. 
Doctor Gitperr. If you had consulted with Doctor Rich before 
you attempted that experiment I think you might have had better 
results. We had this same experience. The known power of regen- 
eration of fins was a difficult factor to deal with until we ascertained 
that if you cut deep enough below the articulation of the rays with 
the underlying structures no regeneration will occur. You may cut 
the caudal fin off one-half inch from the base and that entire fin 
will regenerate. I took a harness punch and made circular cuts in . 
the fin. ‘They also filled up completely. There was nothing to show 
that this had been done except some pigment markings. If you will 
cut deep enough, you will find that no regeneration will occur. 
Mr. Bower. I have had something to do, more particularly in an 
administrative way, with the Alaska fisheries for more than 15 years, 
and I think I am in position to pay tribute to the excellent results 
that have been gained by Doctor Gilbert and Doctor Rich and others 
in solving the problems that confronted us when we sought to protect 
and conserve the salmon fisheries in Alaska. I can not use too high 
terms in indorsing the work that has been accomplished. 
Perhaps the record should be made to show the extent of the fish- 
eries of Alaska commercially. Employment is given at present to 
approximately 25,000 men. There is an investment of about 
$60,000,000, and the products, annually, are valued at substantially 
$40,000,000. That gives some idea of the extent of the industry 
with which we are dealing. Prior to the enactment of the law of 
1924, to which Doctor Gilbert made reference, we dealt with the 
fisheries of Alaska as best we could under the law of 1906. We 
realized its inadequacies, but we used the limit of authority given 
