fishery, increased knowledge of the grounds 

 and habits of the fish has also been respon- 

 sible for marked changes in type of gear 

 and fishing practices. For instance, at the 

 beginning of the fishery the flat net was used 

 since this special type of trawl had proven 

 efficient for dragging for fluke in the summer. 

 However, with the discovery by the winter 

 fishery of such fish as scup, sea bass, and 

 croakers, along with fluke, experiments in 

 modification of the flat net produced the bal- 

 loon net, which was more efficient than the 

 flat net for catching scup and sea bass. Since 

 these fish continued to be found in commercial 

 quantities exceeding those for fluke, the bal- 

 loon net is now used almost exclusively by 

 most of the boats engaged in the offshore 

 winter fishery. 



Account has been taken of these influences 

 by computing catch per day's fishing from 

 Information obtained by personal interviews 

 with the captains at time of landing: records 

 of the locations of catch, amount of each kind 

 of fish caught, diversion of fishing effort be- 

 tween the several species, and the kind, 

 amount, and size of fish discarded at sea. 

 Such attempts were not uniformly successful 

 since it is difficult for the captains under 

 ordinary fishing conditions to keep an accu- 

 rate record (especially by memory) of these 

 details. 



There have been changes in the catch per 

 day's fishing that appear to have been far in 

 excess of any that could have been due to the 

 deficiency of the fishing method. These changes 

 suggest that major fluctuations in catch did 

 actually occur and that the data reflect at 

 least approximately the abundance or avail- 

 ability of the scup. 



Although the total yield of scup in the 

 winter fishery increased from approximately 

 1,686,000 pounds in 1931 to approximately 

 3,844,000 pounds in 1935— largely the result 

 of an increase in the number of boats from 

 50 in 1931 to about 120 in 1935~the catch, 

 as measured by catch per day's fishing showed 

 marked fluctuations from year to year. For 

 example, with the beginning of records in 

 1931, the catch per day's fishing was rela- 

 tively high (6,240 pounds); in 1932 it declined 



(2,643 pounds); dropped very low in 1933 

 (1,336 pounds); rose in 1934 (4,008 pounds); 

 and dropped again in 1935 (2,846 pounds) 

 (fig. 9, table 16). 



Causes of changes in yield. — Ob- 

 servations on the catches of the winter trawl 

 fishery were made at the principal ports of 

 landing in Virginia from 1931 to 1935 inclu- 

 sive, and at Wildwood, N.J., in 1931, 1932, 

 and part of 1933. When reduced appropriations 

 necessitated curtailment of activities in 1933, 

 the observations at Wildwood were discon- 

 tinued, because that port received only a 

 minor portion of the catch, and also because 

 the sizes of the scup in catches landed at that 

 port were more highly selected than those 

 landed in Virginia. New Jersey vessels dis- 

 card more of the smaller sizes of fish than 

 do the Virginia boats, their markets having 

 less ready sale for the smaller sizes of fish, 

 especially scup and sea bass. Hence, con- 

 sideration of fluctuations in yield of scup 

 must be confined mainly to the information 

 collected on landings at Virginia ports. This 

 limitation is not overly severe, because these 

 ports receive about 95 percent of the scup 

 landed by the winter trawl fishery. 



It was naturally expected that If the summer 

 and winter fisheries drew on a common stock, 

 the fluctuation in catch of the winter fishery 

 might be due to the same changes in abun- 

 dance as those occurring in the summer 

 fishery. In an attempt to determine whether 

 such .was the case, we used an analysis of 

 the length frequency method to identify and 

 measure the relative importance of the annual 

 recruitment to the stock available to the 

 winter fishery. The analysis revealed that 

 most of the winter catch included the same 

 year classes that appear in the summer in- 

 shore pound net fishery and the summer 

 offshore seine and trawl fisheries (fig. 8, 

 table 17). The relative proportions, however, 

 have not always been the same. In some 

 winters, the younger scup characteristic of 

 the New Jersey summer pound net fishery 

 predominated in the winter catches, and in 

 other winters, the larger sizes characteristic 

 of the summer seine fishery were more im- 

 portant. For example, in the winter of 1931, 



33 



