168 BULLETIN or THE BUREAU OF FISHERIES 



little more than 1 year old. This modal size in April, 1927, corresponds well with the 

 modal length observed for drum of the same age ca'ptiired in April, 1926. 



In late February, 1927, a newly spawned year class appeared (0 year class), which 

 by the end of May, 1927, had attained a modal length of 2 centimeters with a range from 

 1 to 5 centimeters. It will be observed that during May, 1926, a length range from 

 1 to 15 centimeters was recorded, while a year later this range was reduced to 1 to 5 

 centimeters. From the fact that the larger fish included in the O class during May, 

 1926, possessed no winter scale checks, it must be inferred that spawning occurred 

 earlier in 1926 than in 1927 (the scales of the drum were found to show annual winter 

 growth checks, not including, of course, the first winter during which the fish are 

 hatched). This supposition presumes, however, that the larger fish of the class 

 (10 to 15 centimeters long) actually belonged to the year class on account of its 

 lack of a winter check, and that any group of fish hatched in the late summer or fall 

 of 1925 would show a growth check during the winter of 1926. The fact that after 

 the period fi'om May 9 to June 5, 1926, all fish in the O year class fell into a more or 

 less regular group would seem in itself to justify the inclusion of these larger fish 

 in the youngest year class. 



Some confusion was caused by the capture of a considerable number of drum 

 from December 5, 1926, to January 28, 1927, showing a modal length at about 15 

 centimeters (5.9 inches), while the modal length of the O year class reached 21 centi- 

 meters (8.2 inches) during the preceding October. This small group of drum was 

 reflected in the catches during the next few months, and nearly all fish were taken 

 from Oso Bay. (See table 14.) WhUe it is possible that this undermodal group of 

 the year class of drum was the result of the suggested spawning in the late summer 

 and fall of 1926, the belief of the writer is that the group merely represented a late 

 season's hatch in the spring of 1926, as indicated by the collection of many young fish 

 around Oso Bay on May 13, 1926. Such differences within a single year class can 

 easily result from the arrival of various schools of adult fish on the spawning grounds 

 at different times. With the existing doubt as to the results obtained from the effort 

 of some fish to spawn in the late summer of 1926, however, the writer suggests the 

 possibility that some yovmg may come from this spawning and be represented by these 

 subnormal modes at about 16 centimeters instead of 23 to 24 centimeters, as appeared 

 typical of the year class in December, 1926, and January, 1927. Future work could 

 easily clear up the present uncertainty as to the extent and influence of any late 

 summer spawning, which, with the information at hand, appears to be negligible. 



It seems reasonable to state, on the basis of an examination of the drum length- 

 frequency distribution composed of about 4,350 fish taken with unselective gear, 

 that a modal length of about 25 centimeters (9.8 inches) is reached by the end of the 

 first year and about 37 centimeters (14.5 inches) is attained by the end of the second 

 year. 



The age of the black drum, up to a length of 60 centimeters (23.3 inches), usually 

 may be determined by a count of the annually formed winter-growth checks on the 

 scales. The extremely large size and the heavy calcification that the drum scale 

 undergoes render the determination of age difficult and unreliable after the fish has 

 reached the fourth or fifth year of life and generally has attained a length of 50 to 60 

 centimeters (19-7 to 23.3 inches). In general, the winter-growth checks of the drum 



