FISHES OF THE GULF OF MAINE 



197 



tomcod is decidedly smaller than that of a cod 

 (about one-fifth to one-sixth as long as the head 

 in the tomcod, about one-fourth in the cod, in 

 fish 7 to 10 inches long) ; and the general form of 

 its body is more slender. A less obvious difference 

 is that the first dorsal fin of the tomcod originates 

 over the middle of the pectoral fins or farther back 

 still, farther forward in the cod; and the pectoral 

 fins reach back only a little beyond the middle of 

 the first dorsal fin in the tomcod, but nearly to the 

 rear end of the first dorsal on a cod. 



Unfortunately, the number of fin rays varies so 

 widely in both these fish that it is not diagnostic, 

 there being from 11 to 15 in the first dorsal, 15 to 

 19 in the second dorsal, and 16 to 21 in the third 

 dorsal of the tomcod: 12 to 21 in its first anal fin 

 and 16 to 20 in its second anal fin. Most of the 

 recent accounts list the position of the vent as 

 the chief external distinction between tomcod and 

 cod, describing it as in front of the origin of the 

 second dorsal fin in the former and back of it in 

 the latter. But we must caution the reader that 

 it is only for adults of the two species (which no 

 one could confuse in any case, cod being so very 

 much the larger) that this distinction holds; cod 

 as small as tomcod (that is, up to a foot long) often 

 have the vent well in front of the second dorsal, 

 while it may hardly be further forward than that 

 in adult tomcod in breeding condition. 



Color.- — Tomcod are not so variable in color as 

 cod. Those we have seen (a considerable number) 

 have been olive or muddy green above, with a 

 yellowish tinge, darkest on the back, paling on the 

 sides, and mottled with indefinite dark spots or 

 blotches. The lower parts of the sides usually 

 show a decided yellowish cast in large fish; the 

 belly is grayish or yellowish white; the dorsal and 

 caudal fins are of the same color as the back; the 

 anals are pale at the base but olive at the margin ; 

 and all of the fins are more or less dark mottled. 

 The tomcod has often been described (following 

 Storer) as thickly speckled with black dots, but 

 we have never seen one marked in that way. 



Size. — The maximum size is about 15 inches 

 and VA pounds, but few of them are more than 9 

 to 12 inches long. 



Habits. — The tomcod is strictly an inshore fish; 

 probably few ever descend more than two or three 

 fathoms, or stray as much as a mile outside the 

 outer headlands. In our Gulf they chiefly fre- 

 quent the mouths of streams and the estuaries into 



which these empty, as well as shoal, muddy harbors 

 like Duxbury Bay. As often as not they are in 

 brackish water, and they run up into fresh water in 

 winter. Dr. Huntsman, for example, writes us 

 that they are caught in the Petit Codiac River 12 

 miles above the head of tide. Tomcod are less 

 plentiful in harbors where there is no stream drain- 

 age, but now and then they are caught off open 

 shores, off Nahant, for instance, and such fish are 

 usually large ones. South of Cape Cod, most of 

 them move out from the shore into slightly deeper 

 (hence cooler) water in spring, coming in again in 

 autumn to winter in the estuaries. But a year 

 comes from time to time (such as 1925) when they 

 are plentiful close inshore all summer, as far south 

 even as New York. 12 And they do not carry out 

 any inshore-offshore migrations of a regular sort 

 in the cooler Gulf of Maine, so far as is known. 

 Indeed, they are so resistant to cold that we find no 

 record of them killed by winter chilling, a fate that 

 sometimes overtakes other fishes that live in shoal 

 water. And they are equally hardy toward sudden 

 changes of salinity. 



Tomcod feed chiefly on small crustaceans, es- 

 pecially on shrimps and amphipods, a great variety 

 of which have been found in their stomachs; also on 

 worms; small mollusks; squids; and fish fry, such 

 as alewives, anchovies, cunners, mummichogs, 

 herring, menhaden, launce, sculpins, silversides, 

 smelt, and sticklebacks. 



According to Herrick 13 tomcod arc not so keen- 

 sighted as pollock nor so active as hake, but spend 

 most of their time quietly on the bottom in the 

 aquarium. His experiments also proved that they 

 are able to recognize concealed baits by the sense of 

 smell if they chance to swim near and that they 

 search the bottom by dragging the chin barbel and 

 the sensitive tips of the ventral fins as they swim to 

 and fro, either for food, or to stir up shrimps and 

 other food items. 



Tomcod spawn in the shoal waters of estuaries, 

 in stream mouths and such places, either in salt 

 water or in brackish, and their eggs have been 

 hatched artificially in fresh water. The season 

 lasts from November to February, inclusive, with 

 the height of production in January. The eggs are 

 about 1.5 mm. in diameter with a conspicuous oil 



ii Nichols and Breder (Zoologies, N. Y. Zool. Soc, vol. 9, 192", p. 166) state 

 that tomcod up to 1094 inches long were common throughout that summer In 

 Sundy Hook Bay. 



" Bull. U. S. Fish Comm., vol. 22, 1904, p. 262. 



