104 UNIVERSITY OF COLORADO STUDIES 



first spine of the anal, dorsal spines XII to XIV, rays 19 to 22; anal spines II, 

 rays 12 to 14; scales rather small, strongly ctenoid, 10 to 12, 80-100, 20 to 25; 

 size large; reaching length of 3 feet and a weight of 10 pounds or more. 



Color olivaceous above, shading to almost white below, sides brassy; region 

 above the lateral line mottled with dusky spots; dorsals and caudal dusky, the 

 soft dorsal and the caudal somewhat barred with rows of spots on the rays; eye 

 brown, golden yellow near the center, cornea milky white, hence the name, 

 "Wall-eye." 



This species ranges throughout the central portion of the Mississippi Valley, 

 being quite abundant in the northern lakes. It is a voracious fish feeding upon 

 other fishes^ and to some extent on crayfish. Because of its large size and vigorous 

 fighting when hooked as well as its firm white flesh it is prized as a game fish of 

 considerable importance. It is known in Colorado only from a few of the eastern 

 lakes where it has been introduced from the East. 



Subfamily Percinae 



Genus PERCA (Artedi) Linnaeus 



The River Perch 



Perca (Artedi) Linnaeus, Syskma Naturae, ed. X, 1758. 



Body compressed, not much elongate; back elevated; spinous dorsal of XII 

 to XVI spines; size moderately large. 



The three species of this genus are known from the northern hemisphere only, 

 one occurring in Asia, one in Europe and one in North America. They are 

 locally quite abundant and are esteemed as food fishes. The American species 

 has been introduced into the lakes and ponds of eastern Colorado and from these 

 has escaped into some of the streams. 



Perca flavescens (Mitchill) 

 Yellow Perch, Ringed Perch 



Morone flavescens Mitchill, Repl. Fish. N.Y., p. 18, 1814. 



Body somewhat elongate, distinctly compressed, especially in the posterior 

 half, back elevated; depth 3 to 3 . 5 in the length to the base of the caudal; head 

 large and compressed, its length equal to or slightly greater than the depth of the 

 body; top of the head slightly depressed just above the eyes, making the snout 

 rather prominent ; snout 3.5 to 4 in the head ; eye large, situated in the dorsal 

 half of the head, nearer to the tip of the snout than to the posterior margin of the 

 operculum; dorsal margin of the eye about one-fourth the length of the snout from 



' Forbes, op. c, pp. 273 and 274, states that "reckoning the average life of a pike at three years, the 

 smallest reasonable estimate of food for each pike-perch would fall somewhere between eighteen hundred and 

 three thousand fishes": also that "the young [wall-eye] begin to practice their carnivorous instincts on each 

 other when only about ten days old." 



