420 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



any given locality is governed by their food at the 

 time. On open coasts they often feed on bottom 

 right in the surf. They also feed on bottom in 

 estuarine waters when dieting on bottom-living 

 animals, but in the upper water layers when 

 preying on small fish. 



Weakfish feed on a wide variety of animals, 

 including crabs, amphipods, mysid and decapod 

 shrimps, squid, shelled mollusks, and annelid 

 worms, but chiefly on smaller fish, such as men- 

 haden, butterfish, herring, scup, anchovies, silver- 

 sides, and mummichogs, of which thej r destroy 

 vast quantities. The precise diet varies with the 

 locality (that is, with what is most readily avail- 

 able), but small menhaden are probably the most 

 important single item. The adult weakfish usu- 

 ally depend on fish, though occasionally they have 

 been found feeding exclusively on crabs and 

 shrimps. The young depend more on shrimp and 

 on other small crustaceans than the adults. 76 

 Weakfish bite greedily on various kinds of bait, 

 especially on shedder crabs, clams, shrimp, and 

 mummichogs or other small fish. And they are 

 often caught on artificial lures of one kind or 

 another. 



The females do not make an^y sounds, but the 

 males have well-developed croaking muscles in the 

 walls of the abdomen, with which they make a 

 drumming noise. 



Breeding habits.- — On the middle Atlantic coast 

 the weakfish spawn from May to October, with 

 the chief production of eggs between mid-May and 

 mid-June. 76 The eggs have been taken in tow 

 nets at various localities in temperatures ranging 

 from 60° to 70°, in salinities of 28.01 to 30.9 per 

 mille. And it is probable that weakfish spawn 

 locally around the shores of Cape Cod Bay in 

 years when the fish are plentiful there, as they do 

 regularly about Woods Hole, if the summer 

 temperature of the surface is high enough. 

 Spawning takes place chiefly in the larger estuaries 

 or close to their mouths, usually at night. The 

 eggs are buoyant, spherical, 0.74 to 1.1 mm. in 

 diameter, usually with one, rarely with as many 

 as four, oil globules that coalesce into one large 

 one as development progresses. Incubation oc- 



cupies 36 to 40 hours at a temperature of 68° to 

 70°, and the newly hatched larvae are 1.75 mm. 

 long. 



At 30 mm. the young weakfish have attained 

 most of the structural characters of the adult. 

 But they continue much deeper and more flat- 

 tened sidewise until they are 6 to 8 inches long; 

 the head and eyes are relatively larger; and their 

 caudal fin is obtusely pointed with the center 

 rays much the longest, instead of concave. The 

 smaller fry {\}{ to 3 inches) are marked with four 

 dark, saddle-shaped patches extending downward 

 on the sides to a little below the lateral line, which 

 are not lost until a length of about 4% inches is 

 reached. As the young fish grow, other bands of 

 pigment are interpolated below the lateral line, 

 the adult coloration not being fully developed until 

 they are 7 to 8 inches long. 77 



Bate of growth. — Weakfish fry grow at so variable 

 a rate during the first summer that they may be 

 anywhere between 4 inches and 6 inches long in the 

 fall, when they are about 6 months old. The 

 smallest fish seen in spring (no doubt yearlings) are 

 8 to 10 inches long. Thereafter the rate of annual 

 growth is slower. But the variation in the length 

 attained by the fry during their first summer and 

 autumn, consequent on the protracted spawning 

 season, combined with the fact that scale studies 

 of this species have proved puzzling, make it diffi- 

 cult to group the older age classes by size. As far 

 as known, a weakfish of 10 to 12 inches is likely to 

 be about 2 years old; one of 13 inches, about 3 

 years; 15 inches, about 4 to 5 years; 18 inches, about 

 5 or 6 years; one of 22 inches about 6 to 7 years 

 old; 78 24 inches perhaps 9 years; and 30 inches per- 

 haps as old as 12 years. Both males and females 

 usually mature at 2 to 3 years of age, i. e., when 

 10 to 13 inches long. 



General range. — Eastern coast of the United 

 States from the east coast of Florida to Massachu- 

 setts Bay, straying northward to the Bay of Fundy, 

 and perhaps to Nova Scotia. 79 



71 For diet lists of weakfish of various sizes, see especially Welsh and Breder 

 (Bull. U. S. Bur Fish. vol. 39, 1924, p. 159); also Peck (Bulletin U. S. Fish 

 Comm., vol. 15, 1896, p. 352). 



™ The following account of the breeding and development of the weakfish 

 Is condensed from Welsh and Breder (Bull. U. S. Bur. Fish., vol. 39, 1924, p. 

 150). 



" Tracy (Thirty-eighth Ann. Rept. Comm. Inland Fish., Rhode Island, 

 1908, pp. 85-91), Eigenmann (Bull. U. S. Fish Comm., vol. 21, 1902, p. 45), and 

 Welsh and Breder (Bull. U. S. Bur. Fish., vol. 39, 1924, p. 154) describe the 

 older larvae and fry. 



»» According to studies by Taylor (Bull. U. S. Bur. of Fish., vol. 34, 1916, 

 p. 318); by Welsh and Breder (Bull. U. S. Bur. of Fish., vol. 39, 1924, p. 158); 

 and by R. A. Nesbit, formerly U. S. Bur. Fish, (unpublished). 



'» It is credited indefinitely to "Maine" by ITolmes (Fishes of Maine, 1862, 

 p. 74); Ooode (Fish. Jjid. U.S. Sect. 1, 1884, p. 362), states that scattering indi- 

 viduals have been caught as far as the Bay of Fundy; and Ilalkett (Check 

 List Fishes Canada, Newfoundland, 1913, p. 87) mentions one as probably 

 caught off Nova Scotia. 



