16 TJ. S. BUREAU OF FISHERIES. 



is gray, with purplish reflections ; the sides of the head and body are 

 lighter, with purplish and silvery iridescence ; the belly is pure white ; 

 there are a few V-shaped black spots on the anterior part of the body ; 

 a dark heavy line, more distinct in males, extends along upper border 

 of belly from ventral to pectoral fins. The dorsal fin is richly varie- 

 gated with a rosy border, four to six rows of roundish rosy spots in 

 whitish areas, with dark blotches forming lines between the spots. 

 The ventral fins have three rose-colored branching stripes along the 

 rays. The anal and pectoral fins are plain with dark border. 



The Michigan gi^ayling resembles, in general, the fish of Montana, 

 but is distinguishable by its larger dorsal fin and certain differences 

 in coloration. The Arctic grayling has a higher dorsal fin with 

 22 to 24 rays, a smaller head, contained five and one-half times in 

 length of body, and more brilliant colors; the back and sides are 

 purplish gray, the belly blackish gray with irregular white blotches, 

 and the head brown ; on the anterior part of the body are five or six 

 deep blue spots, and on each side of lower jaw a blue mark; the dark 

 gray dorsal has pale blotches and cross rows of rich blue spots edged 

 with red ; the ventrals show red and white stripes. 



SIZE. 



The Michigan grayling rarely exceeds a weight of 1^ pounds, and 

 the average is probably not more than one-half pound. In Montana 

 waters the average weight of Thymallus montanus is somewhat 

 greater. As is true with all fish, the size is governed to a consider- 

 able extent by the water temperature, food supply, and other local 

 conditions. In Georgetown Lake, Mont., where the Montana Fish 

 and Game Commission has been eminently successful in its efforts 

 to establish the species, the average weight is placed between 1^ and 

 2 pounds, and although specimens taken in the South Fork of the 

 Madison River weighing as high as 3 pounds have been recorded 

 they seldon exceed 2 pounds in weight. 



SPAWNING HABITS. 



Grayling prefer clear, cool streams with sandy or gravelly bottom, 

 although they will at times extend their range to streams where the 

 bottom is strewn with bowlders and broken rock. Unlike salmon 

 and trout, it would appear that grayling make no attempt at nest 

 building. In this respect they, perhaps, more closely resemble the 

 whitefish, as they deposit their eggs in the small eddies formed by 

 roots and rocks or on natural barriers of sand and gravel. 



In Michigan, where spawning occurs in April, the eggs are nor- 

 mally laid in the gravel beds of clear streams having a temperature 

 range between 50 and 60° F. In certain tributaries of the head- 

 waters of the Madison River, in Montana, they spawn in February 

 and March, while farther down the river, near McAllister and • 

 Ennis, the fish spawn late in April or in early May. In Ashley, 

 Ronan, and Rogers Lakes the height of the spawning season occurs 

 late in May and is at least two weeks later in Georgetown Lake. 



Grayling usually ascend the tributaries of the larger streams, 

 being very partial to spring-fed creeks for spawning purposes. 

 They are persistent swimmers and whenever possible will ascend 



