PROGRESS IN BIOLOGICAL INQUIRIES, 1937 33 



w'liile data obtained from the marking experiments indicate that the 

 chars grow only about one centimeter a month during this period. 

 Hence, it appears that these lish have a relatively long life span, a 

 supposition Avhich is, in a measure, confirmed by the otolith readings. 



Both scales and otoliths have been examined and it has been found 

 that the scales are virtually useless as a means of age determination, 

 and that the otoliths, while of some value, are not altogether satis- 

 factory. This difficulty makes the study of the life history much more 

 complicated and other methods of age determination are being tried. 



At Karluk Lake it was noted that chars take a very heavy toll of 

 red salmon fry in the spring at the time the young fish are entering 

 the lake from the spawning streams. However, during the summer 

 and fall relatively little damage is done to the salmon populations by 

 these chars. They have been caught by means of seines and gill nets, 

 and only rarely was one found that had been feeding on salmon finger- 

 lings. Although salmon eggs do comprise a large part of the diet of 

 these fish, it was noted that the chars were feeding almost entirely on 

 floating eggs displaced by the spawning activities of the salmon and 

 these eggs would die whether they were eaten or not. An analysis of 

 stomach contents of chars in Karluk River showed that the chars in 

 the river were not feeding on seaward migrants. 



PINK SALMON 



The pink salmon investigation in southeastern Alaska was continued 

 in 1937 by Dr. F. A. Davidson and Samuel J. Hutchinson. The inves- 

 tigation, as in the past, covered numerous pink salmon research prob- 

 lems. Activities were about equally divided between the sunmier field 

 work in Alaska and the compilation of scientific data at the laboratory 

 in Seattle. The summer field station at Little Port Walter, Alaska, 

 was operated for its fourth consecutive year, remaining in active opera- 

 tion throughout the summer from May 20 to September 20. 



The runs of pink salmon in southeastern Alaska during the 1937 

 season were comparatively light in practically all districts. The 

 total pack of canned salmon was below average but the proportionate 

 take of the total population was as gTeat, if not greater, than in pre- 

 vious years. Catch statistics and studies of escapements into the 

 streams for each district show that in the majority of cases the spawn- 

 ers were insufficient in number to make adequate use of all the avail- 

 able spawning ground atforded throughout the region. In 1937, the 

 rainfall was in excess and most streams provided suitable water condi- 

 tions for that portion of the population that successfully escaped the 

 intensive commercial fishery. 



All through Alaska the trend is toward cannery modernization and 

 increased capacity. As a result the amount of fishing gear is expand- 

 ing in an efi'ort to increase the take of raw material. It is clear that 

 the saturation point has been reached in all districts in southeastern 

 Alaska and that the industry must, to maintain itself, be content with 

 a smaller average pack per plant if it is to continue in the future. The 

 problem facing the production of salmon in Alaska is nothing more 

 than a farming problem. Seed must be planted if a crop is to be 

 produced, and part of the cro]) produced must be conserved for seed. 

 The spawning grounds are of limited size, tending to decrease rather 

 than increase, thus making it impractical to think of the salmon 

 resources as an ever increasing commodity. 



