DISTRIBUTION OF PURSE SEINE SETS 



The distribution of purse seine sets is shown 

 in figures 2, 3, and 4 where the calculated 

 relative numbers of purse seine sets were 

 plotted by 10- minute unit areas. The data were 

 compiled from logbooks of daily fishing ac- 

 tivities furnished by the vessel captains or 

 pilots. Complete logbook data were obtained 

 for 59 percent of the total landings. Compared 

 with the previous 3 seasons, the following 

 differences were most apparent: (1) In the 

 South Atlantic Area, fewer sets were made, and 

 there was no fishing from central Georgia to 

 central South Carolina; a greater amount of 

 effort was expended between lat. 33° and 34° N. 

 and in the vicinity of lat. 36° N.; (2) in the 

 Middle Atlantic Area, there was greater amount 

 of fishing beyond the 20-fathom contour; and 

 (3) in the North Atlantic Area, there was a 

 marked reduction in fishing north of Cape Cod 

 (less than 50 sets were made in those waters 

 in 1958). 



SAMPLING THE CATCH 



fishery and for every 857 tons caught in the 

 North Carolina fall fishery. 



In 1958, about one-third of the vessels in the 

 fleet adopted an electrical shocking device to 

 aid in pumping the catch from the net into the 

 hold. The fish in the net are attracted to and 

 immobilized by an electrode fastened to the end 

 of the suction hose, thus facilitating the pump- 

 ing of the fish (Kreutzer, 1959). Since it is 

 known that larger fish in the net are affected 

 more strongly by the electrical current than 

 smaller fish and thus would be pumped into 

 the hold first, it is possible that the catch 

 would be stratified by size. To determine 

 if stratification occurred, samples occasionally 

 were taken from different levels in the hold 

 during pumping operations and the length- 

 frequency distributions of the fish compared. 

 Results showed that variation was no greater 

 than would be expected in sampling a homo- 

 genous population; hence, it was concluded that 

 the use of electrical shockers did not cause 

 stratification of fish in the hold. Results of 

 four such tests are given in table 3. 



The 1958 catch- sampling program was con- 

 ducted in the same manner as in previous 

 seasons, except that no samples were obtained 

 at Portland, Maine (only four landings were 

 made at that port in 1958). The number of 

 samples taken at other plant locations is 

 given in table 2. One sample was obtained for 

 every 660 tons of fish caught in the summer 



TABLE 2. — Number of samples taken from purse seine 

 catches of Atlantic menhaden, 1958 



Age Composition 



The most outstanding features of the age 

 composition in 1958 were the dominance of the 

 1956 year class (age-2 fish) and the decreased 

 proportion of older year classes (table 4). Of 

 an estimated 2.8 billion fish in the catch, the 

 1956 year class accounted for 1.7 billion, or 

 61 percent. This was the largest contribution 

 of age-2 fish in the past 4 seasons. The 1957 

 year class (age-1 fish) accounted for an ad- 

 ditional 31 percent with an estimated 0.9 

 billion fish. This was only about half the num- 

 ber contributed at the same age by the 1955 

 and 1956 year classes. The newly recruited 

 1958 year class (age-0 fish) furnished an ad- 

 ditional 0.1 billion fish, or about 4 percent of 

 the total. Older year classes (fish of ages 3-10) 

 furnished slightly more than 0.1 billion fish, 

 compared to 0.3 billion in 1957 and 0.6 billion 

 in 1955 and 1956. 



The percentage age composition of the 

 summer catches in the different areas and of 

 the fall catch off North Carolina is shown in 

 figure 5 and listed in table 5. The calculated 



