30S 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



Color. — Usually dull olive brown above, the 

 upper part of the sides faintly barred or blotched 

 darker; the belly silvery; the pubic and thoracic 

 regions often black. The color varies, however, 

 with the season of the year, with the state of 

 sexual maturity, and with the color of the bottom 

 on which the fish is living, those on dark mud being 

 darker and those on bright sand paler. All 

 become more brilliant during the breeding season 

 when reddish tints appear under the head, the 

 belly turns greenish, and black dots develop here 

 and there over the entire body. The male has 

 also been described as assuming a rosy tint 

 beneath. 



Habits. — Since the range of the nine-spined 

 stickleback hardly touches the open waters of our 

 Gulf, we need only note that its mode of life is 

 much the same as those of its three-spined relative 

 next to be considered (p. 308); that it is similarly 

 destructive to the spawn and young of other fish, 

 and similarly pugnacious. Probably it spawns 

 in summer w on the shores of the Gulf, for its 

 breeding season in northern Europe covers June 

 and July. The male often (but not always) builds 

 a nest attached to grass or weeds which the female 

 spawns, and he guards nest and eggs until the 

 latter hatch, which occurs in about 12 days. 



General range. — This is one of the most widely 

 ranging of northern fishes, occurring both in 

 fresh water and in salt in the northern parts of 

 both hemispheres; from northern Scandinavia to 

 France, the western Mediterranean and the Black 

 Sea on the European coast; from Arctic seas south 

 to New York along the American, and westward 

 to Saskatchewan and Alaska. 



Occurrence in the Gulf of Maine. — This stickle- 

 back is to be found all around the shores of the 



» At Woods Hole it spawns in April and May. 



Gulf of Maine from Nova Scotia and the Bay of 

 Fundy to Cape Cod, but it is chiefly restricted 

 there to harbors and the creeks in salt marshes, 

 where large numbers may often be taken in com- 

 pany with the mummichogs that swarm in such 

 locations, and where it is to be found throughout 

 the year. It is also found in fresh water. In 

 fact, the most exposed situations around the Gulf, 

 where we have heard of it, are Biddeford Pool, 

 Maine, 61 Passamaquoddy Bay, 62 and St. Mary's 

 Bay on the west coast of Nova Scotia. 



Commercial importance. — -This stickleback is of 

 no commercial importance in America, but it is 

 sometimes tried out for oil in northern Europe 

 when enough can be caught. 



Three-spined stickleback Gasterosteus 

 aculeatus Linnaeus 1758 



Two-spined stickleback; Stickleback; Thorn- 

 fish; Thornback 



Jordan and Evermann, 1896-1900, p. 747. 



Description. — The three-spined stickleback has a 

 very slender caudal peduncle, and squarish tail fin, 

 like its nine-spined relative, but it is a stouter fish, 

 being about one-fourth as deep as long, and it is 

 more flattened sidewise. Its most diagnostic 

 characters are the number of dorsal spines, of 

 which there are three (occasionally four and rarely 

 five), with the first two usually much the larger, 

 and each with a small triangular fin membrane; 

 the small size of the anal spine (this is free in the 

 three-spined stickleback but attached to the fin by 

 the fin membrane in the four-spined) ; and espe- 

 cially the presence of a series of 28 to 33 bony 

 plates on each side, besides a single ventral plate 



•i MacCoy, Bull. 74, Boston Soc. Nat. Hist. 1935, p. 16. 

 " Huntsman, Contr. Canadian Biol., (1921) 1922, p. 61. 



Figure 167. — Three-spined stickleback (Gasterosteus aculeatus). Woods Hole. From Jordan and Evermann. Drawing 



by H. L. Todd. 



