CONTENTS 



Page 



The sounding tube 2 



Application to longline gear 3 



Causes of skewness and excessive readings 5 



Conclusions 7 



Summary 8 



Literature cited 8 



Appendix, tables 3-9 10-16 



ILLUSTRATIONS 



FIGURE Page 

 Frontispiece: Diagram of a longline set. 



1. Essentials of the sounding tube gear 2 



2. Regression lines calculated from laboratory and field sounding tube data compared with a 



theoretical line having a slope of 1 3 



3. Diagram of a basket of 13-hook albacore gear used by POFI in the central North Pacific . 3 



4. The scale model showing the mainline of a basket of longline gear 4 



5. Three general positions at which longline gear is retrieved 6 



6. Depth distribution of hook 7 on baskets of longline 6 



7. The theoretical relation of the distance between buoys to the depths of various hooks on a 



basket of albacore longline 8 



