794 



SCANDINAVIAN FISHES. 



82V'o" of that tVoia the same ])oint to tlie dorsal tin. 

 The j)real)doininal length measures on an average 22',A, 

 %, and the postabdominal length 18'o ?», of the length 

 of the Ijody. 



The texture of the thin scales has already been 

 remarked. It is fairly eiiaract eristic of the Bleaks and 

 their nearest relatives, in the dense, concentric striae, 

 most dense in the anterior (covered) part of the scale, 

 around the eccentric nucleus, which also lies in the 

 covered part. Towards the nucleus run a few (on the 

 scales of the sides commonly 4, on tiie dorsal scales 

 as many as 10) scattered grooves, extending forward 

 for a greater or less distance from the hind margin 

 (if the scale. The scales are generally of a broad 

 elliptical sha])e (those of the lateral line more quadri- 

 lateral, with the posterior part rounded), the longi- 

 tudinal axis of the ellipse pointing up and down. They 

 are rather large, but deciduous. The inner surface of 

 their posterior part is lined with a dense layer of long, 

 almost filiform crystals, which give them their silvery 

 lustre. 



The colour of the back and the upper part of tlie 

 Iiead is greenish gray. The rest of the body is silvery. 

 The iris is also silver}', Init above the pupil yellowish, 

 with dense, confluent spots of gray. The pectoral, 

 ventral, and anal fins are white, the first pair faintly 

 tinged with green at the anterior margin. The dorsal 

 and caudal fins are gray. 



The Bleak is spread over the whole of Europe 

 north of the Alps, with the exception of Scotland and 

 Ireland*. In Sweden it is common enough, under the 

 names of hoja, Lofia, Bpnloja, Pjiln, Pijn, etc., up to 

 the neighbourliood of Quickjock'' (lat. 67° N.). It does 

 not seem to thrive, however, in the highlands, for it 

 is rare in Lapland, and in Western Jemtland, according 

 to Olsson, it is wanting''. In Finland, where it is 

 called Salakka, a name which at Tornea is altered, 

 says WiDEGREN, to Salk, its range extends, according 

 to Mela, to 68° 20' N. lat. In Norway, a country 

 not very rich in Cyprinoids, the Bleak is found 

 (jiily in the south-east, no further north, accord- 

 ing to CoLLETT, than Lake Mjosen. It lives in the 

 great lakes, in clear rivers and streams, and also in 



the iiuier part of tlie Baltic island-belt, as ^\•e]l as in 

 Gothland and round the coasts of that island. Accord- 

 ing to ScHAGERSTKuji it also occurs in the Sound, at 

 least off Landskrona. 



The Bleak lives in shoals, solitary specimens being 

 never met with, and prefers clear, running water with 

 a stony or sandy bottom. It is consequently found 

 but seldom in small lakes \vith a bottom of weeds or 

 raud. Sportive and lively in temi)erainent, it always 

 kee])S to the surface from spring to autunui, and 

 catches the insects tJiat drop into the water. It loves 

 sunshine and calm, and in rainy and stormy weather 

 makes for sheltered shores. At such times it probably 

 descends some way below the surface, but it does not 

 stay there long, and is never found at the l)ottom, 

 except in autumn, when, like the other Cyprinoids, it 

 retires to its winter-quarters in the depths. Less shy 

 than timid, it soon returns to the spot whence it has 

 been driven away by some noise. On the other hand, 

 it is voracious, and instantly seizes any small sub- 

 stance thi'own into the water. If it finds the morsel 

 unfit for food, it again disgorges its prize. Its food 

 consists principallj' of insects, small crustaceans, and 

 worms. 



At the end of May or begiiniing of June the 

 Bleak assembles in large shoals to spawn in shallow 

 water with a stony or sandy bottom. The shoal ])resses 

 in serried array close to the shore, and seems like a 

 dark cloud in the water. The spawning now begins; 

 the fish leap time after time, at brief intervals, above 

 the surface, and meanwhile deal frequent and rapid 

 bloAvs with the tail on the water, thus producing a 

 hissing sound like that heard wlien a piece of cloth is 

 suddenly torn in two. The roe attaches itself to stones 

 or Uv'igs at the bottom. How soon the eggs are hatclied 

 under ordinary circumstances, we cannot state with 

 certainty, the time allotted by different statements to 

 this j)rocess varying l)et\\'een 24 hours and as many 

 daj's; but it undoul)tedly varies according to the tem- 

 jjerature of the ^vater. Of the growth of the fry we 

 learn from Malm tliat in tlie middle of September he 

 caught young Bleak IB — 23 mm. long in tlie H5je 

 (a stream in S('ania); and in Lake Millar Lill.ieborg 



" Accordiug to our measurements 79 — 8'2"2 %. 

 * Day, 1. c. 



" According to LOwenhjelm, Vet.-Akad. Handl. 1843, p. 411. Tlje statement is, liowever, somewhat dubious, for tlie spawning- 

 season is said to occur in September. 



'' According to Fatio it ascends in the Swiss lakes to a liuight of about 700 ni. above the level of the sea. 



