THE MIGRATIONS OF FISHES. 213 



able are the schools of fish of the salmon family that resort to the great 

 rivers of Siberia after the breaking up of the ice. 



The resort of the fish to the same place is repeated every year with 

 a wonderful regularity. The appearance of the herring in Norway 

 varies at most not more than fourteen days. The energy of the move- 

 ments, is remarkable. The salmon, traveling from the sea to its spawn- 

 ing-places, surmounts considerable difficulties, leaping up to the tops 

 of falls several feet high, and repeating its jumps if it fails at first, till 

 it succeeds. Eels are able to ascend waterfalls forty or fifty feet high, 

 and it has been asserted that they have been known to climb the falls 

 of the Rhine at Schaffhausen ; and since the sluices have been put 

 down they have been able to pass the six falls of the Trollhatta, which 

 have together a height of a hundred feet. 



Fish travel to very considerable distances in these journeys. Brehm 

 estimates that the salmon of the Obi and Irtish travel about 7,000 kilo- 

 metres (4,340 miles) a year up and down the stream ; and salmon and 

 sturgeon often go from 1,500 to 2,400 kilometres (930 to 1,500 miles) 

 from the sea to their spawning-places, and salmon to a height of 2,000 

 feet above the level of the sea. Salmon may occupy six or eight months 

 in going up the stream and accomplishing their spawning, but will re- 

 turn to the sea in one or two months, traveling from ten to thirty kilo- 

 metres {<o\ to 18f miles) a day. 



Fish, like birds, return from the most distant journeys to the places 

 of their nativity. This has been ascertained by marking individuals 

 and watching for their return. This faculty of localization bespeaks 

 a higher degree of intelligence than we have been accustomed to as- 

 cribe to fish. 



The theories that have been proposed to account for these migra- 

 tions have failed to give a fully satisfactory explanation of them. 

 The migrations as a whole may be considered under five heads, of 

 which the first and most important comprises the journeys to the 

 places of spawning. The most notable instances of such excursions 

 are those of the salmon tribe, and of the sturgeon, lampreys, eels, and 

 tunnies. The proper home of all these fish, except the eel, is the sea ; 

 and, besides the eel, all of them except the tunny make yearly consid- 

 erable journeys up the rivers to find places suited to the development 

 of their spawn. Such places are, for the sturgeons, about the middle 

 of the course of the river, in shallow, sandy spots ; for the salmon 

 kind, among the hills near the sources, or in the fountain-streams them- 

 selves, where the water runs in a lively current over a stony or grav- 

 elly bed. The lampreys ascend about as far as the sturgeons. Their 

 young, which are very different in appearance from the parents, may 

 be found in great numbers in nearly all the still brooks and ditches of 

 the middle parts of the river-courses. The eel is the only European 

 fish which goes from fresh water to the sea to spawn. Its joui*neys 

 take place some time before the fish are ready to spawn, an abode in 



