256 NORTHERN FISHES 



Figure 55. Brook stickleback, Eucalia inconstans, 1 \/'i inches long. 



The brook stickleback is found from Kansas to Maine and north- 

 ward into southern Canada. This little fish is abundant in almost every 

 small spring-fed brook in Minnesota and Wisconsin (Greene, 1935) . It 

 feeds on tiny insects and Crustacea. Brook sticklebacks spawn in Min- 

 nesota about the first week of May, depending on the seasonal condi- 

 tions. The nest is a hollow spherical or cylindrical mass of grass and 

 small twigs, several inches long. It is bound together by secretions of 

 the male and is fastened to some object in shallow water. Only a rela- 

 tively few eggs are deposited and these are large for the size of these 

 fishes. Sticklebacks are verj^ pugnacious; they readily attack fishes 

 much larger than themselves. 



GENUS Ptmgitius Costa 



This genus contains the ninespine stickleback found in both salt and 

 fresh waters in northern Europe, Asia, and North America. 



NINESPINE STICKLEBACK 



Pungitius pungitius (Linnaeus) 



The ninespine stickleback (Figure 56) is olive above and much 

 speckled. The sides have dark bars, and the belly is silvery. The body is 

 slender and a little compressed; the portion before the caudal fin is ex- 

 tremely slender. The head is short and blunt, and the eye is wider than 

 the length of the snout. The gill-rakers are long and slender. A ridge 

 or keel is developed along the caudal peduncle. The dorsal fin has 9 

 or 10 free spines and 9 rays. The dorsal spines do not all point in the 

 same direction. The pelvic spines are larger than the dorsal spines. The 

 anal fin has 1 spine and 8 rays. This species reaches a length of about 

 3 inches. 



The ninespine stickleback is very common in the shallow waters of 

 Lake Superior, where it was described by Agassiz (1850) as Gaster- 

 osteus nebulosus. A specimen was taken in Lake Superior at Grand 



