822 



BULI^BTIN OF THE BUREAU OF FISHERIES. 



also for the female grilse, though the males are by far in the majority. Of the 

 grilse, as far as our observations go, not more than 17 per cent are females. 



The middle-sized salmon (of 74-98 centimeters) are the so-called "small 

 summer salmon" of the Dutch market. They present themselves for the first 

 time in the river in May, and they continue to ascend until the end of the year. 

 They are most numerous in June and July, but they form also a very important 



Fig. I. — Diagram illustrating the sizes of salmon ascending the Rhine. The lengths, in centimeters, are given at the 

 lower ends of the vertical lines. The number of specimens of each length is given at the upper end of the proper line. 

 The total number of specimens measured was 4,653. 



Salmon of March-December. — . . . — Salmon of July. 



Salmon of March. Salmon of September. 



xxxxxxxxxxxxx Salmon of May. — Salmon of November. 



part of the August and September salmon. Both males and females appear 

 among these salmon, but the females are in the majority. Though the first 

 arrivals are far from being mature, all these small summer salmon are destined 

 to take part in the propagation of the species toward the end of the autumn. 



The large salmon (the fish of 98-134 centimeters) begin to ascend in Novem- 

 ber, though in some years a few may be taken in October. They are at that time 



