fleets. To be included in the selected fleet, 

 (1) a vessel had to fish at least one less than 

 half the number of months in the season, de- 

 fined above; and, (2) the months during which 

 landings were made had to be the same between 

 adjacent years. It should be noted that few 

 changes occurred in thp trawl fleet over the 

 period considered. 



Applying the above criteria, a series of 

 indices was calculated for each fleet for the 

 period 1946 through 1953, using 1949 as the base 

 year. Pertinent summary data for the analyses 

 are given in tables 6 and 7. 



In figure 13 are plotted measurements 

 of total catch, the catch per boat -month, and 

 fishing effort for the inshore trawl fleet for the 

 8 -year period within the area. Whiting was 

 principally responsible for the relatively high 

 level of abundance in 1947, and the decline in 

 1948 was associated with a decreased abundance 

 of this species on the grounds. Subsequently, 

 the curve reached its lowest level in 1950. The 

 rather sharp increase in 1953 resulted from an 

 increased catch per boat -month of fluke. How- 

 ever, calculated fishing effort shows a generally 

 downward trend after 1947. 



Statistics pertaining to the offshore trawl 

 fleet are presented in figure 14. It may be seen 

 that production has risen appreciably during the 

 latter half of the period considered. Catch per 

 boat -month indicates a slight upward trend, 

 fluctuating about 65,000 pounds over the 7 sea- 

 sons, and calculated fishing effort in 1952-53 

 reached its highest level since the 1946-47 sea- 

 son. The value for the 1946-47 season, however, 

 may be regarded with some suspicion as only 

 about 50 percent of the records were available . 



Interpretation of these results must be 

 made with certain reservations, since both 

 fisheries are affected by various factors inde- 

 pendent of fish abundance as indicated by catch 

 per unit effort. The inshore trawl fleet, in 

 effect, pursues two separate and distinct fisher- 

 ies, each employing different nets, fishing 

 methods, and grounds - one for fluke and the 

 other for roundfish. Trawlers frequently will 

 fish both fluke and roundfish in different areas 

 on the same day. It is impossible to assign the 

 catch to one fishery or the other. In general, 



the average daily catch of roundfish is about 

 twice that of fluke. During periods of heavy 

 roundfish production, landings often are con- 

 trolled by catch limits imposed by the docks 

 handling the fish. Such restrictions rarely apply 

 to fluke. 



These factors undoubtedly influence the 

 total catch and the calculated indices of abun- 

 dance, yet, for purposes of analysis, there is no 

 way of separating the two fisheries or applying 

 methods of adjustment which might yield un- 

 equivocal results. 



Economic conditions also may cause ap- 

 parent fluctuations in yield and measures of 

 abundance derived therefrom. Oftentimes mar- 

 ket demand and accompanying prices dictate the 

 activities of the trawl fleets for varying periods 

 throughout the year. Consequently, certain de- 

 sirable species will be sought to the exclusion 

 of those of lesser market demand. In figure 15, 

 for example, are shown landings of porgy, weak- 

 fish, and fluke, which three species comprised 

 over 83 percent of the inshore trawl catch for the 

 period 1946 through 1953. Although total pro- 

 duction may have little relation to the abundance 

 of these species, the rise and fall of porgy land- 

 ings are contrasted with a more stable weakfish 

 catch and an increase in fluke yield. The in- 

 crease in fluke landings in 1952 and 1953 suggests 

 a real increase in the availability of the fish on 

 the inshore grounds . Market demand and prices 

 paid for fluke in 1952 and 1953 reached the high- 

 est levels in the 8 -year period, thus the decline 

 in porgy landings could have resulted from a de- 

 crease in fishing effort for this species occasioned 

 by increased fishing effort, greater demand, and 

 higher prices paid for fluke. In contrast, figure 

 16 shows landings of porgy, sea bass, and fluke 

 by the offshore trawl fleet for the same period, 

 accounting for over 92 percent of the catch for 

 the 7 seasons. While porgy landings in the in- 

 shore fleet showed a continued decline in 1952 

 and 1953, the yield of this species sharply in- 

 creased in 1952-53 in the offshore fishery. 



In summary, the above factors undoubtedly 

 affect the reliability of calculated indices for the 

 trawl fisheries, and, at best, the measures prob- 

 ably reflect only gross changes in the abundance 

 of individual species on the fishing grounds. 



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