UCHIDA: REEVALUATION OF FISfflNG EFFORT 



ANALYTICAL PROCEDURES 



In the sections that follow, the procedures used 

 in grouping vessels and fishing areas and in 

 treating the data are discussed. 



Classes of Vessels 



The difficulties that arise from differences in 

 fishing power among the vessels may be reduced 

 by separating them into relatively homogeneous 

 classes, using physical features such as gross 

 tonnage. It is convenient, therefore, to determine 

 which of the physical features of the vessels is, on 

 the average, proportional to fishing power, and to 

 use it to group the vessels into classes. 



In a study covering the period 1952-62, the ves- 

 sels were grouped into two size classes according 

 to their bait-carrying capacities. Class 1 vessels 

 had capacities up to 3,000 liters per baitwell 

 whereas class 2 vessels had capacities greater 

 than that (Uchida 1967). But the ability of class 2 

 vessels to catch more fish than class 1 vessels is 

 not necessarily a permanent characteristic. Al- 

 though baitwell capacity was a good measure of 

 fishing power in the 1952-62 study, it did not 

 reflect fishing power of the vessels satisfactorily 

 after 1962. In 1963-70, some vessels with small 

 bait capacities had catch rates as high as or 

 higher than those with larger capacities. 

 Reevaluation of the data showed that gross ton- 

 nage provided a better approximation of vessel 

 performance. CIET and bait capacity were corre- 

 lated significantly in 8 out of 11 yr in 1952-62, but 

 only in 2 out of 8 yr in 1963-70 (Table 2). Correla- 

 tion between CIET and gross tonnage, on the 

 other hand, was significant not only in 8 yr in 

 1952-62, but also in 6 yr in 1963-70. For this 

 study, therefore, vessels of 27 to 44 gross tons 

 were called class 1 and those of 45 to 77 gross tons 

 were called class 2. The selection of the division 

 point between class 1 and class 2 vessels was 

 based on the tendency of CIET, when plotted 

 against gross tonnage, to be closely grouped 

 among class 1 vessels for almost all the years 

 examined. In contrast, CIET of class 2 vessels 

 varied widely in most years. 



The relationship of fishing power to vessel age 

 and to bait usage cannot be overlooked. Among 8 

 class 1 vessels fishing in 1963-70, only 1 was built 

 after World War II whereas 9 out of 12 class 2 

 vessels fishing in 1963-70 were built after the 

 war. The relative comfort and reliability of most 



Table 2. — Correlation coefficients of CIET on baitwell capacity 

 and on gross tonnage of Hawaiian skipjack tuna fishing 

 vessels, 1952-70. A single asterisk denotes probabilities be- 

 tween 0.05 and 0.01; two asterisks denote probabilities equal 

 to or less than 0.01. 



class 2 vessels undoubtedly accentuated the rela- 

 tion between fishing power and tonnage by at- 

 tracting better captains and fishermen. Also, the 

 difference between vessel classes in the amount of 

 bait used was pronounced. Whereas class 1 ves- 

 sels used an average of 8.3 buckets of bait per day 

 fished, class 2 vessels averaged 12.3 buckets. 



Each year in the Hawaiian fishery the same 

 few vessel captains vie for the distinction of being 

 captain of the "top boat." Variability in skill 

 among captains, therefore, complicated the com- 

 parison of fishing power among vessels. Further- 

 more, captains and crew frequently shifted from 

 one vessel to another, taking their fishing skills 

 with them. In 1965-70, for example, a minimum 

 of nine vessels changed captains and the transfer 

 of a highly regarded captain usually involved the 

 transfer of part of his former crew. The shifting of 

 personnel caused some high-producing vessels to 

 become low- or marginal-producers. 



Fishing Areas 



After the establishment of the vessel classes, 

 the data within each size class were then grouped 

 into inshore and offshore fishing areas. In the 

 Hawaiian fishery, the deployment of fishing effort 

 and the resulting catches are recorded according 

 to a statistical area system that was established 

 for Hawaiian waters by the Hawaii State Divi- 

 sion of Fish and Game in 1947 (Uchida 1970). 

 Basically, three general areas are recognized. The 



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