298 FISHES 



females being eighteen inches ; the largest reach 40 to 60 

 lbs. in weight and specimens of 80 or even 200 lbs. have 

 been recorded. It is not known that all these fish are of the 

 same age, some may become mature when only a year old, 

 others at two years or several years, but there is no evidence 

 that any survive after spawning. In the case of Salmo salar in 

 the Atlantic, the young, called parr, remain in the rivers for the 

 first year and then in the following spring, or after two or three 

 years, they "become smolts and descend to the sea. It was 

 formerly believed that the smolts returned to spawn in the 

 autumn of the year in which they descended, but it has recently 

 been shown that they remain more than a year in the sea. 



The migration of the eel, that is to say, of the European 

 Angnilla vulgaris and of other species of Anguilla in other 

 parts of the world, resembles that of Oncorhynchus, except that 

 it is in the opposite direction, but a description of it is given in 

 a special section devoted to the life-history of the eel. The 

 majority of the sturgeons, that is, species of Acipenser, are ana- 

 dromous, the common sturgeon spawning in European rivers 

 about July, but in North America in the Delaware in May. 

 xA.mong the Clupeids or herring family there are several ana- 

 dromous species, such as those commonly called shads, Clupea 

 alosa and C.finta in Europe, and C. sapidissima in North America. 

 The Galaxiidae are mostly confined to fresh water in the southern 

 hemisphere, but G. attenuatus in New Zealand descends to the sea 

 to spawn. Whether the katadromous or descending habit is due 

 to a fresh-water species acquiring the habit of spawning in the sea, 

 or a marine species ascending rivers in search of food, must be 

 decided by the affinities of the species in each case ; the flounder 

 is evidently an example of the latter case, it ascends estuaries 

 to brackish, or even fresh water, but always descends to the 

 sea to spawn. 



Many fresh-water fishes become more or less torpid in the 

 winter in northern and perhaps in southern latitudes. They do 

 not fall into a completely unconscious condition like reptiles and 

 some mammals, but cease to feed and hide in sheltered places ; 

 this is the case with many of the carp family (Cyprinidae) ; the 

 common eel remains buried in the mud or in holes. Marine 

 fishes are not known to hibernate as a rule, they usually retire 

 to deeper water where the reduction of temperature is not very 



