UCHIDA: REEVALUATION OF FISHING EFFORT 



not lead to faulty conclusions about the status of 

 the Hawaiian skipjack tuna fishery. The only 

 serious bias appears to be that fluctuations in the 

 CI SET were slightly exaggerated and those in ef- 

 fective fishing intensity were dampened. 



SUMMARY 



The existence of a linear relationship between 

 catch per effective trip and catch per day fished in 

 1965-70 was described. Based on this relation- 

 ship, catch per day fished was estimated from 

 catch per effective trip for 1948-64. 



Efficiency factors were used to standardize 

 fishing effort of class 1 vessels to that of class 2. 

 The data showed that in 1948-70, efficiency fac- 

 tors for class 1 vessels remained constant relative 

 to class 2 vessels. Fishing intensity, calculated in 

 standard days fished, did not decline over the 

 23-yr period despite the gradual decrease in the 

 number of vessels fishing. Data from the catch 

 reports showed that in the face of this decline in 

 fleet size, the remaining vessels increased effort 

 by fishing more frequently. 



Total catch correlated significantly with 

 C/SDF; therefore, it was a good gross indicator of 

 skipjack tuna apparent abundance. Evidence 

 supported the conclusion that in Hawaiian wa- 

 ters, skipjack tuna apparent abundance was not 

 influenced by changes in the amount of fishing 

 effort expended but by fishery-independent fac- 

 tors. And although effective trips as a measure of 

 fishing pressure in previous studies underesti- 

 mated effort and, therefore, provided a biased 

 estimate of skipjack tuna apparent abundance 

 in the Hawaiian fishery, its use did not lead to 

 faulty conclusions. 



ACKNOWLEDGMENTS 



I am indebted to Kenji Ego and Tamotsu 

 Shimizu of the Hawaii State Division of Fish and 

 Game for their time and effort in designing and 

 issuing the revised catch report forms of 1964 

 from which the basic data for this study were ob- 

 tained. Thanks go also to William H. Lenarz, 

 Gene R. Huntsman, and William Nicholson for 

 reading the manuscript and offering valuable 

 suggestions for its improvement. 



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