FISHES OF THE GULF OF MAINE 



287 



cold waters (30°-32°) on the banks as well as in 

 the higher temperatures (40°-42°) of the deep 

 channels. 87 Apparently it is never found in 

 any numbers in water warmer than 50°, but we 

 hesitate to propose high temperature as the factor 

 barring it from shoal water because there is no 

 evidence that it works inshore in our gulf in 

 winter when this bar would not operate. 



Food. — It feeds on invertebrates, like other 

 small-mouthed flatfishes; European experience 

 points to small crustaceans, starfish, small mol- 

 lusks, and worms, as its chief diet. 88 It is not 

 known to eat fish and does not take a bait often. 



Breeding as it does through a long season, over 

 many degrees of latitude, and in both sides of the 

 Atlantic, the witch spawns in temperatures ranging 

 from close to the freezing point of salt water up to 

 48°-50° F. (p. 288). And experiments, added to 

 captures of eggs naturally spawned, and of newly 

 hatched larvae, have shown that incubation pro- 

 ceeds normally in water at least as cold as 45°-46° 

 F., and as warm as 50°-55° F. 



The eggs are buoyant, spherical, transparent, 

 with narrow perivitelline space (the perivitelline 

 space is broad in the eggs of the dab or Canadian 

 plaice, which overlap them in dimensions), without 

 oil globule, and 1.07 to 1.25 mm. in diameter. As 

 noted (pp. 288 and 203), there is danger of confusing 



•' According to Huntsman, Trans. Roy. Soc. Canada, Ser. 3, vol. 12, Sect. 

 4, 1918, p. 63. 



•• No witch-flounder stomachs have been examined In the Oulf of Maine, 

 so far as we know. 



newly spawned witch eggs with those of the cod 

 and haddock, for they overlap these in size and in 

 season. But identity is easily recognizable after 

 a few days' incubation, for black pigment is to be 

 seen in the gadoid eggs soon after the embryo is 

 visible as such, but does not appear in the witch- 

 flounder eggs until after hatching. 



Incubation occupies 7 to 8 days at temperatures 

 varying from 46° to 49° F., and the newly hatched 

 larvae are about 4.9 mm. long, with a larger yolk 

 sac than those of our other flatfishes. The yellow 

 and black pigment becomes aggregated into five 

 transverse bands on body, yolk (now much reduced 

 in size), and fin folds within a few days after 

 hatching, when the larva is 5 to 6 mm. long. One 

 of these bands is at the region of the pectoral fin, 

 one at the vent, and three of them on the trunk 

 rearward from the vent. The yolk is entirely 

 absorbed in about 10 days after hatching, the 

 caudal rays have begun to appear at a length of 

 15 mm., the rays of the vertical fins are well 

 advanced at 21 mm. and they are complete in 

 their final number at about 30 mm. The eyes 

 are still symmetrical, or nearly so, up to this stage. 

 But the left eye has moved to the dorsal surface 

 of the head in larvae of about 40 mm. And the 

 migration of the eye is complete at a length of 40 

 to 50 mm., when the young fish takes to the 

 bottom. 



The witch is perhaps the most easily recogniz- 

 able of Gulf of Maine flatfishes throughout its 



Figure 147. — Egg (European). After Cunningham. 



TV 



Figure 149. — Larva (European), 16 mm. After Kyle. 



Figure 148.— Larva (European), 10 days old, 5.6 mm. Figure 150.— Smallest bottom stage (European), 42 mm. 

 After Holt. After Petersen. 



Witch flounder (Glyptocephalus cynoglossus) 



