FISHES OF THE GULF OF MAINE 



363 



THE BUTTERFISHES. FAMILY STROMATEIDAE 



The members of this family are deep bodied and 

 very much flattened sidewise, with one long dorsal 

 fin that is soft rayed except for a few short weak 

 spines at its forward end, an anal fin of corre- 

 sponding size and shape, a deeply forked caudal fin, 

 a blunt nose, and a small mouth. The two 

 species that occur on the east coast of North 

 America lack ventral fins, but the extremity of the 

 pelvic bone projects through the skin as a spine 

 but this is so short that it is likely to be over- 

 looked unless felt for. 



Two species occur in the Gulf of Maine: one (the 

 butterfish) a common summer visitor, the other 

 (the harvestfish) a rare stray from the south. 



KEY TO GULF OF MAINE BUTTERFISHES 



1 . The forward one-fourth of the anal fin is only about 2 

 or 3 times as high as the rear portion of the fin. 

 The margins of the anal and dorsal fins are only 



slightly concave in outline Butterfish, p. 363 



The forward one-fourth of the anal fin is at least seven 

 times as high as the rear portion of the fin. The 

 anal and dorsal fins are both very deeply concave 



in outline ... Harvestfish, p. 368 



=■ Pt>pr,lu<; -triaxati THuj 



Butterfish Poronotus triacanthus (Peck) 1800 



Dollarfish; Shiner; Skipjack; Sheepshead; 

 Harvestfish 



Jordan and Evermann, 1896-1900, p. 967, as 

 Rhombus triacanthus. 



Description. — The most distinctive characters of 

 the butterfish are its very thin deep body, like a 

 flounder on edge; the fish is only about twice as 

 long as it is deep to the base of its tail fin (the only 

 common Gulf of Maine species of this shape), 

 combined with a single, long, soft-rayed dorsal fin, 

 an anal fin almost equally long, and a deeply 

 forked tail, but no ventral fins. The absence of 

 ventral fins separates it from the pompanos; the 

 dorsal without obvious spines fromthescup (p. 411) 

 and John Dory (p. 297); the lack of detached dor- 

 sal spines from the triggerfishes, which are, fur- 

 thermore, very different in general aspect (p. 520). 

 And it is easily distinguishable from its relative, 

 the harvestfish (p. 194), which is rare in northern 

 waters, by its much lower dorsal and anal fin 

 (compare fig. 192 with fig. 194). The dorsal fin 



(about 45 rays) originates close behind the axils 

 of the pectorals and tapers at first abruptly and 

 then gradually backward, while the anal (about 40 

 rays) narrows evenly from front to rear. There 

 is a forward-pointing spine close in front of the 

 dorsal fin, so short as hardly to be visible though 

 it can be felt; also 3 very short spines in front of 

 the anal, almost wholly embedded in the skin, the 

 first of which points forward. Both the dorsal fin 

 and the anal extend rearward almost to the base of 

 the caudal fin. 



Distinctive, also, are the long pointed pectoral 

 fins, short head, blunt snout, small mouth, weak 

 teeth, and the short and slender caudal peduncle, 

 which does not have longitudinal keels. The 

 scales are very small, and are easily detached when 

 the fish is handled, and there is a row of very 

 conspicuous mucous pores below the forward half 

 of the dorsal fin. 



Color.- — Leaden bluish above, pale on the sides, 

 with numerous irregular dark spots which fade 

 after death. The belly is silvery. 



Size.- — The largest are about 12 inches long; 

 the general run are about 6 to 9 inches long. The 

 weight runs about 1% ounces at 6 inches, 4 to 4% 

 ounces at 8 inches; about 1 pound at 11 inches 

 (if fat). The largest weigh about l)i pounds. 



Habits. — Astonishingly little is known of the 

 manner of life of the butterfish considering how 

 familiar and valuable it is. As a rule they travel 

 in small bands or loose schools; and draggers re- 

 port catching several times as many by night as by 

 day, suggesting that they are active enough to 

 dodge a trawl, except during the hours of darkness. 

 They often come close inshore, into sheltered bays 

 and estuaries, hence their frequent capture in 

 pound nets. And it shows so decided a preference 

 for sandy bottoms rather than for rocky or muddy, 

 that few are taken in traps on muddy ground while 

 other traps along the sandy beach nearby may 

 yield considerable numbers. General experience 

 is that the butterfish keeps chiefly near the sur- 

 face during its stay near the coast, and schools are 

 often to be seen. At Cohasset (on the south side 

 of Massachusetts Bay), for instance, schools of 

 butterfish, fifty to a few hundred, are often to be 

 seen where the flats are covered by only 4 or 5 feet 



