The 1938 brood of bass grew rapidly In 1938, but slowly In 1939 (discussed later). 

 In these bass collected from Fork Lake, annulus formation extended from mid April to late 

 September, fig. 3. However, only a few had failed to form annuli by the end of July. 

 These were large fish showing marked erosion on the anterio-lateral angles of the scales 

 (plate 2B) and other evidences of starvation (James 1939). 



It may be that the yearling bluegills formed their annuli within a month, and the 

 yearling bass formed annuli over several months, because the former were well fed and 

 growing rapidly, while the latter were partially starved. See plate 4 for comparison. 



The original breeder bluegills made little growth in 1939. In them, annulus forma- 

 tion began later than in the yearlings and was not completed \mtil fall. Delayed annulus 

 formation in these old fish is consistent with the observations of Hansen (1937) on white 

 crappies in Lake Decatur, and of Thompson & Bennett (1939b) on Lincoln Lakes bass. 



In the 1938 broods of bass and bluegills, a number of fish formed one or two addi- 

 tional or false annuli during the latter part of the summer (plates 2 and 3). False 

 annuli appeared in the scales of some of the bluegills collected Jime 16-30, 1939, as 

 indicated in fig. 4, and were found in increasing proportions until September or October. 

 Twenty-four per cent of the yearling bluegills taken after June 16 had these supernumerary 

 annuli. False annuli were not found on the largemouth bass scales until August, fig. 5, 

 but were present in all later collections in increasing proportions, appearing in 38 per 

 cent of all bass collected after the first false annulus in this species was found. Evi- 

 dences of second false annuli in the yearling bluegills were first observed in July; 

 Individuals with second false annuli apparently did not exceed 5 per cent of all the 

 yearling bluegills collected after the appearance of the annuli. In the bass, third 

 annuli had formed in a few individuals taken in the November collection. 



From the time false annuli were first found in the bass until fishing ended in Novem- 

 ber, about 6 per cent of these fish collected showed supernumerary annuli that fulfilled 

 all the criteria of true annuli in the hands of an experienced scale reader using the most 

 critical techniques. About 10 per cent of the bluegills taken after June 16 showed super- 

 mmerary annuli that could not be distinguished from true annuli. In fact, some of the 

 additional rings fulfilled the description of annuli better than the first rings (plates 

 2 and 3). These percentages, 6 for the bass and 10 for the bluegills, give a measure of 

 the probable error of age determination, had the actual ages not been known. In the cases 

 in which the false annuli fulfilled all the known requirements of true annuli, there was 

 distinct "cutting over" across the circuli in the posterior field, and the false annuli 

 did not tend to Join the true annuli in the lateral and posterior fields. In many scales, 

 spacing betv/een the true and false annuli was wide enough to be interpreted as represent- 

 ing a whole year's growth. 



Both sexes showed false annuli in about equal numbers. 



Hubbs & Cooper (1935) have suggested that supemimierary or false annuli are spawning 

 marks. In the material described here this suggestion might conceivably apply for the 

 false annuli of the yearling bluegills, since these fish had a spawning season that cor- 

 responded roughly to the period in which the percentage of false annuli was increasing. 

 However, it could not apply for the false annuli found in the yearling bass, which did not 

 spawn. The percentages of true annuli and of first or second false annuli are shown in 

 figs. 4 and 5. The false annuli described here in both bass and bluegills should not be 

 confused with the spawning checks described by Hubbs & Cooper. At the time of their pub- 

 lication it was generally accepted that the Centrarchids formed annuli in winter. Since 

 that time, Hansen (1937) and Thompson & Bennett (1939b) have shown that white crappies and 

 largemouth bass form their annuli from late spring to autumn. It now appears that what 

 Hubbs & Cooper interpreted as the spawning check (the inside member of a double ring) was 

 a tnje annulus, whereas the outside member may have been the spawning check which they 

 discuss. An examination of their illustrations of scales suggests that the fish were 

 Increasing in length and not in girth, thereby elongating the scale pockets to produce 

 their so-called double rings. 



THE RELATION OF BODY AND SCALE JIEASUREAIENTS 



Greaser (1926) and others have shown that the scales of fishes grow at about the same 

 rate as the fishes themselves. This is because fish have the same number of scales 

 throughout life and because these scales are arranged like shingles on a roof and tend to 

 grow Just fast enough to cover the body. Consequently, measurements of the growth of 

 scales can be translated into measurements of growth of the fish. In some kinds of fish, 

 growth of the scales is almost exactly proportional to the growth of the fish, making it 

 possible to calculate the length of the fish corresponding to that portion of a scale 

 designated by any point or mark on the scale. The annual ring is an example of such a 

 mark. Proportional growth of body and scales seems to prevail in the largemouth bass, 



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