FISHES OF THE GULF OF MAINE 103 



Food. — The herring is a plankton feeder. When first hatched, and before the 

 disappearance of the yolk sac, the larvae (European) feed on larval gastropods, diatoms, 

 peridinians, and crustacean larvae, but they soon begin taking copepods, and after 

 they are 12 mm. long depend on them exclusively for a time, particularly on the 

 little Pseudocalanus elongatus. 2 As they grow older they feed more and more on 

 larger prey, turning to the larger copepods and amphipods, pelagic shrimps, and 

 decapod crustacean larva?. Examination of 1,500 stomachs 3 showed that adult 

 herring near Eastport were living solely on copepods and pelagic shrimps, fish 

 less than 4 inches long depending on the former only while the larger herring were 

 eating both. When feeding on copepods herring swim open-mouthed, often with 

 their snouts at the surface, crossing and recrossing in their tracks and evidently 

 straining out the minute crustaceans by means of their branchial sieves, a straining 

 apparatus of coarser mesh than that of the menhaden and consequently capturing 

 larger plankton and letting the microscopic plants pass through. 



When feeding on euphausiids, as we ourselves have often seen them engaged 

 and with which the large fish are often gorged, they pursue the individual shrimps, 

 which often leap clear of the water in their efforts to escape. Even in winter 

 when shrimp are rarely seen on the surface Moore found them an important article 

 in the diet of the herring, and it is not unlikely that the local appearances and 

 disappearances of schools of large fish in the open Gulf are connected with the 

 presence or absence of shrimp. In the Gulf of Maine these pelagic shrimp (euphau- 

 siids) are taken by herring in preference to any other food, and are voluntarily 

 selected from among the hosts of copepods by such fish as are large enough to 

 devour them. Even when both shrimp and copepods abound, however, a few of 

 the larger fish, as well as the smaller, will usually be found full of copepods, though 

 most of them are packed with shrimp, and in the absence of shrimp (which are seldom 

 abundant west of Mount Desert except during brief periods) copepods are the chief 

 dependence of all our herring, large and small. Such, for instance, is the case at 

 Woods Hole, where copepods had been the chief diet of almost all the herring 

 examined by Doctor Linton during the summer of 1918, and there can be little 

 doubt that they actually select copepods in preference to other small floating 

 organisms, for they are often found packed with them at times and places when 

 the tow nets reveal the presence of a great variety of other animals. In European 

 seas the amphipod genus Euthemisto is also an important food for herring, hence 

 it is to no hesitancy to capture them that the absence of Euthemisto from the 

 fierring stomachs examined by Moore and by us is due, but to the comparative 

 scarcity of this large active crustacean in the coastwise waters of the Gulf of Maine. 



In default of an abundant supply of Crustacea, and sometimes even when 

 these are plentiful, herring feed on whatever molluscan larvae, fish eggs, Sagittae, 

 pteropods, annelids, etc., the water contains, even on objects as small as tintinnids 

 and Halosphaera, but the smaller microscopic plants, either diatom or Peridinian, 

 are never found in the stomachs of herring more than 15 to 20 mm. long, probably 



1 The diet of the young herring in the English Channel has been described by Lebour in a series of papers, especially in Journal. 

 Marine Biological Association of the United Kingdom, Vol. XH, September, 1921, pp. 458-467. Plymouth. 

 s Moore, 1898, p. 402. 



102274—25+ 8 



