FISHES OF THE GULF OF MAINE 



309 



on the lower surface between and behind the 

 ventral fins. The fact that the dorsal fin (1 spine, 

 10 to 14 rays) originates some distance in front 

 of the anal (1 spine, 8 to 10 rays) is diagnostic 

 also, while its ventral spines are longer and stouter 

 than those of the nine-spined stickleback. 



This is one of the most variable of fishes; 

 Smitt, 63 lists no less than 32 named species or 

 races based on its varieties. Thus its dorsal 

 spines may be long or short, and they vary in 

 number as noted above; its bony plates range 

 from none at all to very well developed; and its 

 caudal peduncle may be keeled or it may not. 

 Most American authors have recognized an 

 American species, at the least as contrasted with 

 a European, the former supposedly with longer 

 dorsal spines; the latter with shorter. But the 

 long-spined, as well as the short-spined form is 

 known to occur on the other side of the Atlantic 

 with every possible gradation between the two. 

 Seeing that we have found both in the Gulf of 

 Maine among fish indistinguishable otherwise, 

 we believe that the various forms are environ- 

 mental races of the one species. And this is 

 well established for the relative strength of the 

 dermal armature, which is weak in fresh water, 

 but strong in salt. 



Color.- — This stickleback is extremely variable 

 in color, a fact hardly mentioned in most American 

 accounts. They are deep grayish, or olive, or 

 greenish-brown above, or sometimes blue; paler 

 and often with silvery reflections on the sides; 

 silvery on the belly. The fins are pale, except 

 that the fin membranes often are red. In 

 breeding season the males are described as turning 

 reddish below from nose to vent and often up the 

 sides. In females, the whole body except the 

 top of the back may then be reddish; at the 

 same time the back turns brownish with trans- 

 verse bands, and the sides develop brassy 

 reflections. 



Size. — Maximum length about 4 inches, but 

 few of them are more than 3 inches long. Tt 

 matures sexually at a length of about 2 inches. 



Habits. — This is distinctively a shore fish like 

 all the sticklebacks, the great majority of them 

 living their whole lives in estuarine situations. 

 But it is equally at home in sea water of full 

 salinity as in fresh water. And enough stray 



•> Scandinavian fishes, vol. 2, 1895, p. 648. 



out to sea for it to be rather a common experience 

 to pick up a few here and there in the tow net, 

 far from land. On such occasions they usually 

 hide in clumps of floating eelgrass (Zostera) or 

 of rockweed {Fucus, Ascophyllum) ; indeed we 

 have learned to expect a stickleback or two 

 whenever we dip up bunches of weed of any size. 

 These wanderers keep to the surface except, 

 perhaps, in very rough weather. 



Tt is a permanent all-the-year resident where- 

 ever it is found alongshore, entering creeks and 

 the mouths of streams in the spring to spawn, 

 and dropping down into slightly deeper water 

 for the winter. Tn such situations it probably 

 lies in schools in a more or less sluggish condition 

 while the temperature is lowest. 64 It is a pro- 

 verbially pugnacious fish, using its spines with 

 good effect as weapons of offense and defense, 

 even on other fishes much larger than itself. 

 Tt feeds indiscriminately on the smaller inverte- 

 brates, on small fish fry, and on fish eggs, to 

 which it is exceedingly destructive in fresh water. 

 The diet fist of specimens examined by Vinal 

 Edwards at Woods Hole included copepods, of 

 which they are often full, isopods, schizapod 

 shrimps, and young squid, while some had fed 

 on diatoms only. And it is not only omnivorous 

 but very voracious. 



This stickleback affords the classic instance of 

 nest building and of the care of eggs among fishes, 

 and its nesting has been described so often in 

 popular natural histories that a bare outline will 

 suffice here. 66 Recent studies in Europe make it 

 likely that this stickleback spawns chiefly in 

 brackish or fresh water, if not exclusively there, 

 for which purpose it enters the estuaries and the 

 mouths of streams. The spawning time is pro- 

 bably the same in the Gulf of Maine (May to 

 June) as in north European waters, 66 when the 

 fish assume the nuptial dress described above, and 

 the males fight fiercely. It is the male that 

 builds the nest, selecting some sheltered spot in 

 shoal water for his purpose, or some rock pool. 

 Here he makes a barrel-shaped mass of bits of 

 grass, weed, and other vegetation an inch or so in 

 diameter, cementing it together with mucous 

 threads, which he spins from his kidneys, and 



M Large numbers are sometimes seined In winter in Scandinavian waters. 



« Smitt (Scandinavian Fishes, vol. 2, 1895, pp. 653-656) and Regan (The 

 freshwater fishes of the British Isles, 1911, pp. 247-249) give accounts of the 

 nest building on which the following is based. 



<• About Woods Hole it spawns from May until the last week, in July. 



