58 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. 



in nearly the same latitude as the months of the rivers in which they 

 were born, and return to them at the proper season. The young remain 

 in ths fresh water for a time, the period varying- with the species, after 

 which they also follow their parents in their return to the sea. 



The movements of what we had previously designated as inshore and 

 pelagic fish are also largely connected with the same reproductive in- 

 stinct, and even the fishes of the Banks illustrate it to a greater or less 

 degree. 



Search for food. — Next, perhaps, to the influence of reproduction 

 comes the search for food as influencing the migration and movements 

 of fishes, certain species of fishes following up particular forms of other 

 fishes, the attempts of which to escape fall under the same category; 

 or of the lower animals, as they are carried almost unresistingly by 

 winds and currents in various directions. A notable illustration of this 

 is seen in the herring. 



Professor Mobius, in investigating the food of the herring in the Ger- 

 man seas, found that a certain copepod shrimp, one of the Entomostraca 

 (Temora longicornis), was more eagerly sought after than anything else; 

 this being so minute, however, that 18,000 were taken from the stomach 

 of one herring and 00,000 from that of another.* 



Professor Mobius thinks that the comb like fringes attached to the 

 gills of the herring serve as tangles in' capturing these shrimps, pre- 

 cisely as do the similar apparatus of the basking shark and the whale- 

 bone of the whale. These specimens were obtained in February of 

 1872, when both the shrimp and the herring were in exceptional abund- 

 ance; and he subsequently observes that the same relations were found 

 continually, the abundance of the herring being in strict proportion to 

 that of the shrimp, t 



The chain of connection does not cease in the relation between the 

 Temora or shrimp and the herring. A great variety of sea birds, gulls, 

 gannets, &c, follow up the herring, as also numerous mackerel, tunnies, 

 blackfish, swordfish, and even whales and porpoises, which devour the 

 herring in countless numbers. The movements of the capelin in the 

 North Atlantic influence very largely those of the cod and other species, 

 as when the former come into the shores of Newfoundland and else- 

 where in immense numbers to deposit their eggs on the beach, the cod, 

 &c, follow, and are then captured within a very short distance of the 

 shore. 



Driven by enemies. — A notable instance of these relationships is 

 seen in the menhaden and the bluefish. The menhaden, in its move- 

 ments along the coast, is very frequently accompanied by vast schools 

 of bluefish, which, as already explained in a previous report, probably 

 destroy more menhaden in a day than are taken by man in a whole sea- 



* Circulare ties Deutscheu Fischerei-Vereins, 1873, p. 112. 

 tCirculare des Doutscben Fisclierei-Vereius, 1874, p. DO. 



