PROGKESS IN BIOLOGICAL, INQUIRIES, 19 31 457 



growth has be<run, an annuhis which really was formed in October 

 appears to be formed in July. When the scale resumes growth it 

 does not regain the ground lost during its period of inactivity. Con- 

 sequently, the average scale length of old fish is less than that of 

 younger fish of the same size. 



Keexamination of published observations on rate of growth of her- 

 ring and young cod scales relative to that of the body discloses a 

 similar situation, with the important exception that in these species 

 the sinnmer growth more than compensates for the period of winter 

 inactivity, so that the net result is a gain in scale length relative to 

 that of the body. These facts undoubtedly are an important factor 

 in causing the distortions which have resulted from attempts to cal- 

 culate growth increments from scales. 



/Soup. — The yield of scup has been subject to wide fluctuations dur- 

 ing the past 40 years both in New York and in New Jersey. The 

 record since 1921, covering the period of a significant increase in 

 yield from pound nets, is more complete for New Jersey than for 

 New York. Hence the present discussion will be limited to con- 

 sideration of fluctuations in New Jersey and their causes. 



The pound-net yield, as indicated by periodic canvasses, shows low 

 levels of abundance during the period from 1890 to 1908, followed 

 by increases in 1917 and 1921. In 1926, however, the catches again 

 declined to a level only slightly higher than that of 1908. In 1929 

 a notable increase occurred, the total pound-net catch for New Jersey 

 rising to the highest figure since 1921. This level was well main- 

 tained in 1930 and 1931. 



Compilation and study by W. C. Neville of the data on lengths of 

 scup collected from commercial catches from 1928 to 1931 show that 

 the sudden increase in the scup catch during 1929 was due to the 

 influx of an abundant brood produced in 1927, which first reached 

 commercial size in 1929. In 1928 this group was heavily represented 

 in the catches sampled, but as the fish were below^ legal size they had 

 no effect on the reported yield. 



TVlien they reappeared in large numbers in 1929 they were salable, 

 and raised the reported yield to record figures. But continuation of 

 high pound-net yields in 1930 and 1931 w'as due only in part to the 

 continued presence of the 1927 brood, for the 1928 brood w^as also 

 large and served to offset the diminution in the numbers of 1927 fish 

 returning in these years. 



It is to be noted that both the 1927 and 1928 broods were produced 

 in years in which the pound-net yield was at a low ebb. If the 

 pound-net yield constitutes a reliable index of actual abundance of 

 scup, it might be inferred that even a greatly reduced stock is capable 

 of producing sufficient numbers of eggs to restore high lev^els of 

 abundance, provided conditions for development are favorable. 



That this is not necessarily the case is indicated by data from the 

 offshore fishery during the past few years. In 1928 otter trawlers, 

 purse seiners, and offshore pounds located on Five Fathom Bank took 

 fair numbers of larger and older scup than those wdiich made up the 

 scanty inshore pound-net catch of that year. In 1929, when large 

 catches of scup of the 1927 brood were made inshore, the offshore 

 fishing took few of these, depending, as in 1928, on a stock of older 

 and larger fish than those found inshore. In 1930, and to a greater 



