In the study of changes in the catch per trap 

 per season, data were available from two 

 sources: (1) Annual reports of the New Jersey 

 Board of Fish and Game Commissioners, 

 showing the gross catch of each species and 

 the average number of nets fished during the 

 season; and (2) operators' private records of 

 daily catch and number of nets fished. 



The catch per trap was used instead of 

 catch per lift because the State records on 

 which we depended for earlier years recorded 

 only the number of nets fished and had no 

 record of number of lifts (table 3). All the 

 nets in operation were not always lifted the 

 same day, so that the catch per lift may or 

 may not have represented one or more days' 

 fishing; further, a net fishing 2 days for 

 instance without being lifted the first day did 

 not necessarily catch twice as much as a net 

 lifted after only 1 day's fishing. 



The analysis of changes on the basis of 

 catch per trap is limited to the period 1922-35 

 inclusive, because detailed records for earlier 

 years are not available. From a relatively 

 high yield in 1925, the catch per trap declined 

 to a low level in 1928 but recovered quickly 

 to a record high in 1929 with continued high 

 yields until 1935. Since these changes were 

 measured by the same unit yardstick for all 

 years, the fluctuations in catch were, there- 

 fore, the result not of any increase in nets 

 but of either changes in availability or abun- 

 dance, or a combination of both. Admittedly, 



Table 3. — Catch of scup in New Jersey pound nets and 

 average catch per net, 1922-35^ 



^ Based on annual reports to the State by licensed 

 pouM net operators. 



all parts of the New Jersey coast did not 

 experience the same fluctuations at exactly 

 the same time as shown. This can be seen 

 in table 4 and figure 4 in which the catch 

 per trap for various areas is given. The 

 catch per trap at Wildwood was comparatively 

 high in 1928. Also the increase in catch was 

 apparent at Beach Haven in 1931 compared 

 to that in 1929 at Long Branch. The difference 

 at Wildwood possibly occurred because at that 

 point catches were from traps set on Five 

 Fathom Bank, some 10 miles offshore, and 

 are not strictly comparable with catches made 

 in more inshore areas at Beach Haven and 

 Long Branch. The fact remains, however, that 

 at most points in New Jersey, the trend of 

 catch from 1925 to 1935 was similar. In 1933 

 and 1934 considerable quantities of scup were 

 dumped overboard by pound net operators 

 because the market was glutted. Thus, the 

 reported catch for those years is less than 

 the catch actually made by an undetermined 

 amount of discarded fish. 



Causes of changes in yields . — What 

 caused these changes in yield? We know that 

 changes in the migratory habits of fish often 

 cause the catch to fluctuate; therefore, it might 

 be assumed that such a change in availability 

 may have caused the decrease in catch from 

 1926 to 1928. If this had been the case, how- 

 ever, it was to be expected that a large body 

 of fish may have moved away from the pound 

 net region in 1926 to more offshore areas. 

 If such occurred, they should have been avail- 

 able to the offshore vessel fishery, and good 

 catches should have been made by such gear 

 as purse seines. It is also possible that the 

 fish may have migrated in 1926 from New 

 Jersey waters to other localities (south or 

 north New Jersey), causing a rise in the 

 catch of scup at those points between 1926 

 and 1928. From available records there was 

 no evidence that either the vessel catch in- 

 creased significantly between 1926 and 1928 

 or that unusual increases occurred at other 

 points along the coast. Furthermore, there 

 are no records of marked changes in the 

 hydrography in the region from one summer 

 to another during the period studied (Parr, 

 1933), and, hence, there seems to be no reason 

 to suppose that the fish had migrated away 

 from inshore New Jersey waters. 



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