300 BULLETIN OF THE BUREAU OF FISHERIES 



Five broad growth zones were plainly evident on the scales of the captured fish 

 (Snyder, 1922, p. 107). Three lung salmon hatched in the winter of 1916-17 and 

 marked in the fall of 1917 were captured in the summer of 1920 and according to 

 Snyder (1921) had formed three annuli and an incompleted fourth summer's growth 

 zone on their scales, although, judging from the photomicrographs of the scales, 

 Snyder's conclusion is not wholly convincing, as well-defined accessory checks also 

 appear. The 1919 experiment, however, was the most successful (Snyder, 1922, 

 1923, and 1924). Of 25,000 king salmon hatched in February, 1919, and marked 

 in November, 1919, 23 were taken in the fall of 1921, 23 during the period June 7 

 to November 15, 1922, and 12 during the period June 8 to November 15, 1923. 

 Snyder describes in detail and illustrates the structural features of the scales of the 

 marked fish caught in 1921 and later compares these scales with those removed from 

 the marked individuals taken in 1922 and 1923. In the 3-year (1921) specimens 

 the normal fresh- water nuclear area as well as the second aimulus are sharply defined. 

 A large third-year growth is situated at the margin. In the second growth zone, 

 however, appear two accessory checks, one near the first, the other near the second 

 annulus. These checks were characteristic of the scales of 17 of the 23 salmon caught. 

 The scales of the remaining marked fish differed only "in a minor degi-ee from the 

 others by haA-ing a more or less well-defined check about halfway between" the other 

 two accessory checks. The author associates these accessory or minor checks with 

 the feeding habits of the salmon. Besides indicating that the scales of the marked 

 fish captured in 1921 interpret their age and life history quite accurately, the author 

 compares the nuclear area of these scales with the scales of the yearlings preserved 

 at the time of marking and finds that the two structures are identical. His photo- 

 micrographs illustrate this. 



The scales of the marked salmon taken in 1922 showed one more annulus than 

 those of the specimens taken the previous year. Not only this, but the minor checks 

 found between the first and second annuli in the 1921 fish were also evident in the 1922 

 specimens. The 1922 scales could be identified, therefore, not only by the scales of 

 the preserved yearlings but also by those taken in 1921. So, also, the scales of all 

 the marked specimens taken in 1923 showed the same peculiar anatomic features 

 found in the scales of the previously captured fish with the 1919 mark. They also 

 showed one more annulus than those taken in 1922. The fish were in their fifth year. 



Nail (1925 and 1927) reports on the recapture of 11 marked sea trout. In every 

 case a reading of the scales of the recaptured fish confirmed the first reading and 

 agreed with the known history of the fish, although in every case except one less than 

 one year intervened between the marking and the recapture. 



Sund (1925) published photographs of two scales from each of four saithe, one 

 scale having been removed from the fish at the time of marking in the summer of 1921, 

 the other at the time of recapture in the summer of 1922. The English summary of 

 Sund's article does not state whether the scales correspond with the known history 

 of the fish, but the photographs indicate that the two smaller individuals (53 and 57 

 centimeters) had, at the time of recapture, added one annulus and part of the 1922 

 summer's growth to their scales, while all the scales of the larger fish (80 and 90 

 centimeters) are undecipherable. 



