PROGRESS IN BIOLOGICAL INQUIRIES, 1937 29 



rainbow trout showed that the usual strap tags on the tail or on the 

 jaw were not satisfactory. The Atkins tag through the dorsal fin, 

 however, was well retained and should be tried on a large scale with 

 mature salmon. Its visibility is better than tliat of the strap tag, 

 an especially valuable feature in searching for marked salmon on the 

 spawning grounds. 



A new type of tag was also developed and tried out on fingerli^ig 

 king and sockeye salmon. This mark, which was named the "internal 

 anchor" tag, consists of three parts: an ordinary fiat plate, similar 

 in shape to the nickel herring tag, but preferably smaller; a second 

 small plate of any desired shape, made out of bright -colored celluloid 

 (except bright shades of red which are attacked by other fish) ; and 

 a short piece of fine silver chain. The long flat plate is inserted into 

 the body cavity with the chain (which is fastened to its center) 

 protruding through the body wall; the second plate of bright-colored 

 celluloid is fastened by one end to the free end of the chain. 



In experiments with king salmon fingerlings there was a heavy 

 loss from over-chlorinated city water but after 161 days the survivors 

 were as. follows : 36 percent of the controls, 10 percent of those marked 

 with a large anchor and 20 percent of those marked with a small 

 anchor. These fish were between 2 and 3 inches in length when 

 tagged and the mortality was greater than would be expected from 

 the tagging of slightly larger fish. 



After 85 days the survivors of marked sockej^e fingerlings are: 

 Controls 100 percent, small anchors 91 percent, large anchors 90 per- 

 cent, and medium anchors 100 percent. 



Coho. — The coho sahnon investigation of the causes of the decline 

 in abundance of tliis important commercial and sport fish and of 

 methods for rebuilding runs of former importance was continued dur- 

 ing the past year by (jeorge B. Ivelez. 



During the winter and early spring, final returns from the first 

 Samish River marking experiments - were obtained. The total return 

 of 3-year fish from the two lots of hatchery-reared native stock, 

 marked and released in 1934, was 469 fish. Of these, 7 recoveries 

 were from 26,150 fingerlings, averaging 47.4 mm (approximately 

 1% inches) in length, marked by excision of a pair oi fins in May; 

 and 462 were from an ecjual number of fingerlings, averaging 101.6 

 mm (approximately 4 inches) in length, marked by fin excision in 

 November. The ratio of return of the large fingerlings to that of the 

 small ones indicated a much higher survival rate due to the prolonged 

 rearing period. 



Final returns from 9.800 fingerlings, averaging 49.2 mm (approxi- 

 mately 2 inches) in length, transferred from the Skykomish River and 

 marked and released in the Samish in 1934 were also obtained during 

 this period. Recovery of a total of 11 fish was made from this experi- 

 ment, a return considerablv greater than that from the smaller native 

 fish. 



Marked fish returning from the experiments carried on in 1935 in 

 Voight's Creek, a tributary of the Puyallup River were recovered 

 during the late fall of 1937. Two lots of fingerlings had been marked 

 by excision of diffei'ent pairs of fins. The first of these consisted of 

 50,000 fish reared at the Puyallup River State hatchery, which aver- 



2 See Progress in Biological Inquiries, 1934 and 1936. 



