82 FISHES OF PENNSYLVANIA. 


nels. They feed in spring and early summer among the rapids upon 
insects and small crustaceans. 
Reproduction.—The brook trout is a nest builder. Cavities are made 
in the gravel and the nest is shaped with the tail and the larger stones 
are carried in the mouths of the parents. After the eggs are deposited 
they are covered with gravel. The eggs are not all deposited at one 
time. Spawning usually begins in October, but brook trout are spawn- 
ing at some locality in almost every month of the year except mid- 
summer. The egg is about one-fifth of an inch in diameter, and varies 
in color from pale lemon to orange red. The average yield of the female 
is from 400 to 600. Mr. Livington Stone has taken 1,800 from a fish 
weighing one pound. The period of hatching will depend upon the 
temperature, ranging from 165 days in water of 37° to 32 days in water 
of 54°. The yolk sack is absorbed in from 30 to 80 days, and after its 
absorption the young fish begin to feed. The rate of growth will of 
course depend upon the amount of food consumed. In artificial culture, 
yearlings, according to Mr. Ainsworth’s estimate, will average two 
ounces; two-year olds four ounces; three-year olds eight ounces, and 
four-year olds one pound. 
The value of the brook trout as a food fish, and its game qualities are 
so well known that I need not refer to them here. 
94. Salvelinus namaycush (Wats. ) 
The Lake Trout. (Figure 8.) 
The lake trout or Namaycush hasastout and moderately elongate body. The caudal 
dal peduncle is slender, its height little more than one-third greatest height of body. 
The eye is large, placed near the top of the head, two-thirds as long as the snout, 
and contained four and a-half to five and a-half times in length of head. The rmax- 
illa reaches far behind the eye; its length is nearly one-half that of head. The ori- 
gin of the dorsal is midway between the tip of snout and root of tail. The length 
of the base equals length of maxilla. Its longest ray one-sixth of total without 
caudal. The ventral is under the hind part of dorsal; itslength half length of head. 
The appendage is very short, about one-half length of eye. The fin when ex- 
tended reaches nearly to the vent. The distance between ventral origin and anal 
origin is one-fifth total length without caudal. Theanal baseisabout one-third length 
of head. The longest ray one-half length of head. The last ray equal to eye. The 
pectoral is nearly two-thirds as long as the head. B. 11 to 12; D. 9 to 10, besides sey- 
eral rudiments; A. 9 and several rudiments; V.9. Scales of lateral line about 200. 
The coloration is extremely variable, generally grayish, in the variety known as 
the Tuladi, nearly black. Alaskan specimens are usually very dark; occasionally 
the upper parts are pale. The sides are profusely covered with roundish pale spots, 
sometimes with a reddish tinge. On the back and top of head there are fine vermic- 
ulations resembling those of the brook trout. The caudal in addition to numerous 
pale spots has many small dark blotches. 
Names.—The lake trout has received many names, among which are 
the following: Mackinaw or Namaycush, Togue, Tuladi and salmon 
trout. Additional names of the species are Lunge, red trout, gray 
trout and black salmon. Togue and Tuladi are names applied in Maine, 
New Brunswick and Canada, Mackinaw and salmon trout in the Great 
