46 SALMON AND TROUT IN ALASKA. 



the latter lot is slightly smaller, but the decrease is not sufficient to 

 indicate a movement of the larger individuals out of the lake. A 

 more significant fact is the growing scarcity of surface food and 

 o-reater amount of bottom material — the caddis found in tlieir 

 stomachs. 



As early as April 6 (1903) coho yearhngs of 145 to 165 mm. were 

 gilled at the Fortmann Hatchery in Heckman Lake at the mouth of 

 the river. They were attracted by the waste eggs thrown in the 

 river. 



May 17, 1903, 11 males taken at station 2 averaged 119 mm., and 

 8 females 112; May 24 of the following year 12 males averaged 125 

 and IS females 123. If these may be regarded as typical there 

 appears to be a growth of about 50 per cent between September and 

 May, or about twice that which from similar data was estimated for 

 the sockeye. The yearling cohos taken in the Naha were found to 

 eat the young salmon fry whenever taken mth them in the nets. 

 That they sometimes were able to pre}^ upon them in a natural state 

 was evidenced by the presence of digested fry in some examples that 

 were seined in Roosevelt Lagoon in May. 



September 12, 1897, the ^^Titer seined a number of young cohos at 

 the mouth of Klawak River. No other fish except sticklebacks were 

 noted. Of the 71 cohos saved the 37 males averaged 85 mm. in 

 length (50-125); the 34 females averaged a small fraction of a milli- 

 meter greater (47-135). At this time the hatchery was operating 

 and sockeyes were spawiiing in the lake tributaries above. Many of 

 these young cohos contained salmon eggs. A more common food 

 was a large maggot, probably the blowfly larva? from dead fish 

 along the stream. One stomach contained 2 leeches, and man}^ of the 

 smaller had insects. Examples taken with a hook in brackish water 

 at the Klawak cannery wharf contained insects and a few beach 

 crustaceans; 50 examples from the lake, October 14, 1905, averaged 

 about 75 mm. These were taken with a dip net and do not give the 

 average size of lake residents of that date. (See also record in salt 

 water, p. 53.) Like the king fingerhng the coho is readily taken 

 with a hook, either with a fly or bait, salmon spawn being especially 

 attractive in season. During the spawning season the coho in a few 

 places may do some damage to the sockeye eggs. Large numbers 

 are attracted to the scene of the hatchery work at Loring by the 

 washings from the freshl}^ spawned eggs. They wxre nowhere noted 

 in any number on the natural beds. 



As the result of the wide diversity of spawning regions, the coho 

 may be said to possess three movements seaward, first as fry, second as 

 fall fingerlings in the same manner as the king, and third as yearlings, 

 lake winter residents leaving in the spring with the sockeyes. This 



