TIME AND MANNER OF ASCENT OF RIVERS. 47 



where two weirs are built on the same hedge that near shore takes more salmon than the 

 other.' 



Time and Manner of Ascent of Rivers. 



By those who have investigated salmon and salmon rivers it seems to be quite generally 

 conceded that in some rivers adult salmon are present at least to some extent every 

 month in the year. If such is the case, the question is why are they there when the 

 spawning time is a comparatively limited period in late fall or early winter? 



In connection with this subject the caution expressed by Miescher-RUsch (1883, 

 p. 462) in referring to other points of discussion, may well apply to the consideration of 

 the present subject. He said: 'In reviewing this whole subject I feel compelled to warn 

 people not to apply the experiences gained in other rivers to the Rhine salmon, and 

 vice versa.' And later he remarked that, 'The habits of migration, therefore, seem to 

 vary in the different rivers, perhaps according to the length of the route traveled and 

 the extent of distribution in the sea within which certain kinds are found.' He also 

 added: 'From what is known relative to the salmon fisheries of Scotland and Norway, 

 the habits of life of the fish, even, seem to vary.' At about the spawning time of salmon 

 in the neighborhood of Basel, he shows that there are other salmon, which he calls 

 'winter' salmon, that are not in breeding condition but are fat marketable fish. These 

 fish, he maintains, and presents data in evidence, remain in the river until the next fall. 



Miescher-Rusch did not apply his data to the lower Rhine. As he had not been able 

 to observe the Dutch and North Sea salmon during the season of the year, he could not 

 decide whether, as Barfurth said, numerous large salmon, in almost a mature condition, 

 immigrate from the sea late in summer and during autumn, and all that he maintained 

 was that such belated immigrants, with the exception of a few male fish, did not go up 

 as far as Basel. 



Hoek (1910, p. 821-823), however, in 1893 made extensive observations upon the runs 

 of salmon of the lower Rhine in Holland. After referring to the work of Miescher- 

 Rusch in 1878 and 1879, in which it was demonstrated that three different ages were 

 represented in the salmon of Basel Market and that the difference in age between the 

 youngest and middle-aged salmon was about the same as that between the latter and 

 the oldest fish, Hoek says: 'To check the results arrived at by the Basel professor, I 

 ordered to be measured for me (1893) a large number of salmon caught near the mouth 

 of the Rhine and offered for sale at the Kralingsche Veer market. From March to 

 December 4,653 salmon were measured and the curve constructed with these figures 

 corresponds in the main with that given by Miescher-Ruesch for the Basel salmon.' 



Hoek then shows that the salmon of the Rhine present themselves in three sizes: 

 smallest, 54 to 74 centimeters, mean 64 centimeters (2 to 4 kilograms) ; middle size, 74 

 to 98 centimeters, mean 88 centimeters (6 to 10 kilograms); largest, 98 to 134 centi- 

 meters, mean 106 centimeters (12 to 25 kilograms). Of these fish he says: 'The fishes of 

 different sizes do not enter the river together or in a haphazard way. The different 



