£32 U. S. BUREAU OF FISHERIES. 
reater than is indicated by these figures, for in 1919 comparatively 
low fish of larger size were taken out for mild curing, while in 1920 
there were put up 145 tierces of mild-cured kings, with 800 pounds 
to the tierce. These were all selected from the larger sizes and would 
have materially diminished the number required per case if all had 
been canned. 
During the early part of the fishing season the king salmon were 
silvery in color, without trace of red; the testes are small, hard, and 
purplish in color; the eggs are always small, not more than half the 
size when mature. The snout of the males was then so little pro- 
duced as to give no certain indication of sex. This condition con- 
tinued during the greater part of June, near the latter end of which 
the run indicated a decided falling off. But on June 29 a second 
run appeared of small dimensions, and it was at once apparent that 
these fish were further along in their development. The jaws of the 
male were now somewhat prolonged and hooked, and the enlarged 
teeth had begun to show. They were now reddish in color, and the 
bellies were so thin that they were little valued for mild-cure pur- 
poses. These changes were abrupt and coincided with the sudden 
increase in the run. 
The natural enemies which left traces of their presence on the 
entering salmon were the white whales, or belugas, and the lamprey 
eels. Belugas were very much in evidence in the lower river chan- 
nels during the latter part of the season, the size of their schools 
increasing as the salmon were running more abundantly. Un- 
doubtedly they were feeding on the salmon, and it is safe to assume 
that they captured and devoured a very large proportion of those 
on which they succeeded in closing their jaws. But the number of 
salmon which appeared on the cannery floor bearing unmistakable 
tooth marks of the beluga was surprising. The sides were scored 
lengthwise by widely spaced lines, which usually described a gentle 
curve, but were occasionally angulated. Evidently these salmon had 
escaped from the very jaws of their pursuers. 
Other marks which attracted universal attention and were usually 
mistaken for hatchery brands were the scars made by the lamprey 
eel. This slender eel-shaped animal has an oval sucker-shaped 
mouth provided with rows of rasping teeth. By means of the sucker 
mouth it attaches itself to the salmon and may rasp off the skin 
and even deeper-lying tissues for food. A scar is left which often 
reproduces with great fidelity the details of the mouth, with its 
outer fringe of filaments and its inner groups of teeth, which in 
the scar often give the impression of printed characters. 
Such lamprey scars have been occasionally observed in other 
rivers, but never before in such abundance as on the Yukon. This 
fact probably stands related to the large lamprey run which is 
indigenous to this stream. They enter the mouth of the river in the 
fall after the surface has frozen and run up under the ice, to the 
under surface of which they often attach themselves when resting. 
Although the run lasts but few hours at any locality, it is of enor- 
mous dimensions and furnishes tons of food to those who dip them 
up through holes cut in the ice. 
Like the salmon, the lampreys enter the river for purposes of 
propagation, and all die after the eggs are laid. The young soon 
