FISHERY BULLETIN: VOL. 69, NO, 4 



season. They also used linked groups of vessels, 

 but simplified calculations by using catch per 

 lunar month rather than catch per week. 



June and Reintjes (1957), studying the men- 

 haden fishery off Delaware Bay, used the linkage 

 method to determine the catch per boat week 

 for selected boats from 1939 to 1953. They esti- 

 mated the total number of boat weeks by dividing 

 the total catch by the catch per boat week. 



In the yellowfin tuna (Thunmis albacares) 

 bait-boat fishery in the eastern tropical Pacific, 

 Shimada and Schaefer (1956) grouped vessels 

 by carrying capacity. They computed the catch 

 per days absence from port for each grouji and 

 established one group as a standard. They 

 standardized effort by dividing the catch per days 

 absence of the standard group by the catch per 

 days absence of each other group. Broadhead 

 (1962) related the catch per day of bait boats to 

 the catch per day of purse-seine vessels by using 

 regression analysis. 



Menhaden i^lant records, while showing the 

 date and amount of fish landed by each vessel, 

 do not list days when vessels fish and catch 

 nothing, and do not indicate whether a catch 

 represents 1 or more days' fishing. While ves- 

 sels generally land their catch daily, quite often 

 in the Middle and North Atlantic areas they 

 land 2 or 3 days' catch at one time, particularly 

 in late spring and early fall, a jjractice which 

 has increased in recent years as fish have become 

 scarce and daily catches smaller. 



There is no satisfactory way of getting the 

 complete daily history of each vessel. Even if 

 port samplers recorded each vessel's daily ac- 

 tivity, the records still would be incomplete be- 

 cause not all ports are sampled and because no 

 ports were sampled prior to 1955. Logbook 

 records also are incomjilete. Any eflFective meth- 

 od of measuring efl!'ort. therefore, must use ves- 

 sel landings as they are recorded at the plants. 



Fortunately, menhaden vessels generally op- 

 erate continuously throughout all or part of the 

 fishing season and fish every day that weather 

 permits, unless in port for repairs. Except in 

 the North Carolina fall fishery, which lasts only 

 6 to 8 weeks, the number of days that had weather 

 I)rohil)its menhaden fishing is relatively small 

 and is relatively constant from year to year. 



Any time period, therefore, that assumes con- 

 tinuous fishing and accounts for unproductive 

 fishing days should be a satisfactory unit of basic 

 fishing effort. Because the vessel week satisfies 

 these conditions and may be readily computed, 

 it was selected as the basic unit. 



Because variations in the catch per unit of 

 effort among vessels may necessitate ad.justing 

 the basic unit to a common standard, the rel- 

 ative efficiency of vessels fishing from each port 

 was examined. 



No clear correlation could be shown between 

 catch per week and vessel length or weight, so 

 the relation between mean catch per week and 

 vessel carrying capacity was explored. Carry- 

 ing capacity, determined for each vessel by aver- 

 aging the 10 largest catches for 3 consecutive 

 years, ranged from about 100 to 350 short tons 

 (90-317 metric tons). Vessels were grouped, 

 according to their carrying capacity in short 

 tons, into six cla.sses: 



Class 



1 

 2 

 3 



4 

 5 



6 



Carrying capacity 



<141 

 141-180 

 181-220 

 221-260 

 261-300 



>300 



The relative efficiency of vessels at each port 

 was examined by plotting the mean catch per 

 week of each vessel and by plotting the catch 

 lier week against carrying capacity. 



In the South Atlantic area all vessels were 

 class 3 at Fernandina Beach, Yonges Island, and 

 Southiiort. and class 1 or 3 at Beaufort. Vari- 

 ation in the catch per week among vessels was 

 evident at all jjorts, but there was no distinct 

 tendency for any group to have larger or smaller 

 catches per week than another. 



Until about 1963 nearly all vessels in Ches- 

 apeake Bay were class 3, although a few were 

 class 2, 4, or 5. After 1961 the number of class 

 5 vessels increased. Although the large capacity 

 vessel tended to have greater mean catches per 

 week than small capacity vessels, the variation 

 was extreme among all vessels, both between and 

 within years. As the catch per week declined 

 after 1 961 , the variation between vessels of small 

 and large capacities decreased. 



770 



