Fishes of the Western North Atlantic 285 



To capture such prey requires some address on the part of the herring; they frequently throw themselves 

 almost clear of the surface and their splashings. . . are audible at a considerable distance. When feeding on 

 copepods the movements of the herring are less impetuous. They swim open-mouthed, ^^ often with their snouts 

 at the surface crossing and recrossing on their tracks and eventually straining out the minute crustaceans by means 

 of their branchial sieves. 



The sieves were described by Moore (95: 401) as follows: 



An examination of the mouth cavity of the herring wiU disclose a series of long bristle-like processes, 

 the gill rakers, projecting from the anterior face of each gill arch, like the teeth of a comb. When the mouth is 

 opened widely the tips of the gill rakers stand apart, but when it is closed or partly closed they become more 

 closely approximated and each series is pressed closely against the inner face of the series attached to the arch 

 next in front. There is thus formed a beautifully fine and effective sieve, capable of retaining small bodies contained 

 in the water taken in at the mouth and discharged through the gill slits. 



The amphipod genus Euthemisto is also an important food for this species off 

 Europe ; that this is not so in the Gulf of Maine no doubt reflects the scarcity of this 

 pelagic crustacean in our coastal waters. In default of an abundant supply of Crustacea, 

 and sometimes even when these are plentiful, the fish feed on whatever other kinds of 

 smaller planktonic animals and plants may be available. Small fish of various kinds 

 have been found in their stomachs: capelin, especially in Newfoundland waters in 

 winter; and grass shrimps (Crago), schizopod shrimps (Mysis), amphipods (Gammarus), 

 small squid, annelid worms, and crab larvae at Woods Hole, Massachusetts. But the 

 smaller planktonic plants, whether diatom or peridonidian, have never been found in 

 specimens longer than 1 5 mm, probably because their gill sieves are not fine enough 

 to retain them. 



Enemies. Their chief natural enemies include all kinds of marine predators, such 

 as cod, pollock, haddock, silver hake, mackerel, dogfish and other sharks, finback 

 whales, and the common squid {16: 104). An attack on a school of young Atlantic 

 Herring by squid has been described by Hildebrand and Schroeder {^g : 82) as follows: 



We had occasion to watch the wholesale destruction of 2 to 4 inch herring during June 1925, on the flats 

 about Provincetown, Mass. Schools of 10 to perhaps 50 squids circled around a school of herring until they had 

 bunched their prey into a compact mass. Individual squids then darted in and seized one, sometimes two, and then 

 darted back for more. Along the beach there remained a silvery streak of dead herring. 



A similar firsthand account of silver hake {Merluccius bilinearis) driving a school of large 

 Atlantic Herring up on the beach in Massachusetts Bay has been reported {15: 90). 

 Parasites. Among the European fish, "cestode larvae and trematodes were fre- 

 quently found as parasites in the gut. The latter were common and the incidence ap- 

 peared to increase as the herring grew, as many as 29-30 per cent being parasitized 

 in the large catches of May 2 1 and 30. Cestode larvae were less numerous, and they 

 too were more frequent in the older fish" (Marshall, et al., gi: 253). No fatalities 

 were specifically ascribed to these parasites; Sindermann and Rosenfield have found 

 that infestation with trematode larvae may be fatal — at least under experimental con- 



14. That the larger herring "swim open-mouthed" when feeding on copepods has been questioned by Batde, et al., 

 who are of the opinion that the fish seize the organisms individually (7:411). However, as to the organisms ingested 

 there is general agreement. 



