476 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



thermal limit, for the well being of the cunner, is 

 something like 70°-72°, to judge from the distri- 

 bution of the species. 



Cunners are omnivorous. As a rule they find 

 their livelihood browsing among seaweeds, stones, 

 or dock piles, biting off barnacles and small blue 

 mussels, with the fragments of which they are 

 often packed full. They devour enormous num- 

 bers of amphipods, shrimps, young lobsters, small 

 crabs, and other small crustaceans of all kinds; 

 also univalve mollusks and the smaller bivalves, 

 hydroids, and annelid worms. They sometimes 

 eat small sea urchins, bryozoans, and ascidians, 

 and they occasionally capture small fish such as 

 silversides, sticklebacks, pipefish, mummichogs, 

 and the fry of larger species. Finally, eel grass is 

 often found in cunner stomachs besides the animal 

 food. Small cunner fry taken at Woods Hole 

 were found by Dr. Linton to have fed chiefly on 

 minute Crustacea such as copepods, amphipods, 

 and isopods. 



The cunner is a busj r scavenger in harbors, con- 

 gregating about any animal refuse, to feed on the 

 latter as well as on the amphipods and other 

 crustaceans attracted by the same morsels. They 

 are also said to eat fish eggs, and no doubt feed to 

 some extent on herring spawn. Our own belief 

 is that cunners are always hungry, no matter 

 what the stage of the tide. 



The cunner spawns chiefly from late spring 

 through early summer. The eggs are buoyant, 

 transparent, 0.75 to 0.85 mm. in diameter, and 

 they do not have an oil globule. Incubation 

 occupies about 40 hours at temperatures of 70° to 

 72°, but it is probable that about 3 days are 

 required for hatching in the cooler waters of the 

 Gulf of Maine (55° to 65°). At hatching the 

 larvae are about 2 to 2.2 mm. long, and at 15 mm. 

 the young cunner is of practically adult form. 

 On newly hatched larvae the pigment cells are 

 scattered uniformly over head and trunk, but by 

 the 3-mm. stage they have gathered into a pair of 

 black spots, dorsal and ventral, about halfway 

 between the vent and the base of the caudal rays, 

 which are characteristic of the species. And these 

 spots persist to about the 10- to 20-mm. stage. By 

 the time the fry have grown to about 25 mm. they 

 are as variable in color as their parents (it is on 

 record that Louis Agassiz had 60 colored sketches 

 of small cunners 3 to 4 inches long, of different 



hues, prepared at Nahant during a single sum- 

 mer). 76 



Fry of 1 to 1.2 inches have often been taken in 

 August, and young fish up to 2 inches long in 

 September in southern New England waters. 

 Hence we may assume that Gulf of Maine cunners 

 (probably hatched somewhat later) may average 

 about 2 to 2% inches by their first autumn, and 

 2% to 2% inches by the following June when they 

 are one year old, which Johansen 77 found true 

 also of the earliest hatched fry in the southern 

 side of the Gulf of St. Lawrence. The subsequent 

 rate of growth has not been studied for the cunners 

 of our Gulf. But Johansen's 78 age determina- 

 tions for cunners of the Gulf of St. Lawrence make 

 it likely that Gulf of Maine cunners 3 to 4 inches 

 long are 2 years old; those of 4 to 5 inches 2 or 3 

 years old ; those of 5 to 6 inches 3 years old ; those 

 of 6 to 7 inches 3 or 4 years old; those of 7 to 8 

 inches 4 or 5 years old; those of 8 to 9 inches 5 or 

 6 years old; those of 9 to 10 inches about 6 years 

 old; and those of 10 to 11 inches 6 or 7 years old. 

 But the relationship is complicated by the fact 

 that female cunners run larger than males, so that 

 males may be a year older than females of the 

 same size. 



Most of the cunners mature in their third 

 summer (i. e., when 2 full years old) when 2% to 

 3% inches long. 



General range. — Atlantic coast of North Amer- 

 ica and the offshore banks, from Conception Bay, 

 east coast of Newfoundland, and the western and 

 southern parts of the Gulf of St. Lawrence, 79 

 southward in abundance to New Jersey, and 

 occasionallv as far as the mouth of Chesapeake 

 Bay. 



Occurrence in the Gulf of Maine. — The cunner is 

 one of our most familiar fish, to be found all 

 around the shore line of the Gulf. The Massa- 

 chusetts Bay region is perhaps their chief center of 

 abundance, and they are so numerous there in 



r * The embryology and larval development and fry of the cunner have 

 been described by Agassiz (Proc. Amer. Acad. Arts, Sei., N. Ser., vol. 9, 

 1882, p. 290, pis. 13 to 15); Agassiz and Whitman (Mem. Mas. Comp. Zool., 

 vol. 14, No. 1, Pt. 1, 1885, p. 18, pis. 7-19, and Mem. Mus. Comp. Zool., vol. 

 40, No. 9, 1915, pis. 32-39); Kuntz and Radcliffe (Bull. U. S. Bur. Fish., vol. 

 35, 1918, p. 99, flgs. 18-29); and more recently by Johansen (Contr. Canad. 

 Biol., N. Ser., vol. 2, No. 17, 1925, pp. 44(M50). 



" Contrib. Canadian Biol., N. Ser., vol. 2, No. 17, 192B, p. 451. 



'• Johansen (Contrib. Canadian Biol., N. Ser., vol. 2, No. 17, 1925, pp. 

 451-455) worked out the age-length relationship for a large series of Gulf of 

 St. L3WTence cunners by a study of their scales and otoliths. 



'• See Johansen, Contrib. Canadian Biol., Ser. 2, vol. 2, No. 17, 1925, 

 pp. 5-6 [427-428]), for the distribution of the cunner in Canadian waters. 



