574 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



tlie kinds wliich one prizes as objects of esijecial care, as corresponds 

 with the existing" nourishing capacity of the water-area. The more min- 

 nows which under such conditions occur, and the better they thrive, the 

 more profitable for the development of the species of fish which one de- 

 sires to produce as the particular fruit of culture. 



A species related to this — 



The MoRT {Leuciscus rutilns), occurs in the eastern and southern 

 portion of the country in nearly all the waters and rivulets with a cur- 

 rent not too strong and with a muddy bottom, up to a somewhat lower 

 level than the preceding. It will probably also admit of being planted 

 in waters more elevated than those in which it is now found. It is, as 

 the most of the genera belonging to the great cyprinoid family, i)artic- 

 ularlj' fruitful. It spawns in spring, in April and May. There is no diffi- 

 culty in the way of its introduction in great numbers, if it be found 

 necessary in this way to insure that the supply of this food may not di- 

 minish too much, which may easily occur with merely natural reproduc- 

 tion, where the spawn as well as the tender young are the defense- 

 less prey of every fish, small and large, of other and even the same 

 kind. At a still lower height occurs another cyprinoid — 



Lau or LojE {Alburnus htcidus), which occurs in large lakes and 

 rivers, but resembles the mort in habits and appearance; the most evi- 

 dent difference is that it has a yellow iris, while the mort has a red 

 one. It spawns on grassy bottoms, at the same time as the mort, 

 and might j^erhaps be introduced to more elevated waters. Both of these 

 species feed on aquatic plants as well as aquatic insects. It tlirivesthus 

 in a less degree than other fishes of choicer kinds, if the insect world 

 yields it nourishment. 



The Karudsen {Gyprinus carassius) lives in j^ools and ponds Avith 

 muddy bottoms, up to a height of 150 to 200 metres above the sea-leveL 

 It will probably easily admit of being transferred to more elevated j)lacea 

 in still waters with muddy bottoms. It lives, as the two species pre- 

 viously named, to a great extent on vegetables, occasionally rotten ones. 

 It spawns in May and June, and is very fruitful. The Karudsen may 

 reach a very considerable size, even up to one kilogram, and are then 

 considered well flavored. 



Of the salmon family occur, as before intimated, in the great Scandina- 

 vian lakes, two species, which may be mentioned. 



Slom or ISToRS {Osmerus epcrlanus) and Lake Herring or Sikloje 

 {Coregonus albula) appear abundant in very numerous schools where 

 they are found. Both occur in Mjosen, where the last, at the spawning 

 time in autumn, is now and then caught in great multitudes, many hundred 

 barrels. In Sweden, also, the nors is caught in great abundance at the 

 spawning time, which occurs in March to April. The attempt has been 

 made to introduce the lake-herring into many of our larger lakes, but the 

 attempts hitherto made have, so far as is known, not succeeded. If suffi- 

 cient care should be exercised, it might be possible to introduce both 



