14 



<n 10 



o 

 o 



X 



O 8 

 o 



a: 



Ld 



°- 6 



X 



u 

 < 



<-> a. 



INSULAR STATIONS < 10 MILES FROM LAND 

 OCEANIC STATIONS > 10 MILES FROM LAND 



r 



MAR I APR I MAY | JUN | JUL | AUG | SEP | OCT | NOV I DEC | JAN I FEB 



1955 1956 



Figure 11. --Daily yellowfin longline catch rates in the Line Islands, 1955-56. 



Longlining 



The daily longline catch rates throughout 

 the year for the Line Islands area are presented 

 in figure 11. When two vessels fished on the 

 same day an average rate is used. The longline 

 catch rates at insular stations generally are 

 higher than those at oceanic stations, which were 

 consistently low during these cruises. The maxi- 

 mum catch rate for oceanic stations of 3. E yellow- 

 fin per 100 hooks was made in September. For 

 the remainder of the year catch rates were below 

 3 yellowfin per 1 00 hooks with the majority below 

 1 yellowfin per 100 hooks. Exannination of the 

 catch rates by latitude indicates no difference 

 between areas. 



The insular catch rates, on the other 

 hand, show considerable variation throughout 

 the year. Two possible sources of variation 

 resulting from sampling procedure are: fishing 

 at different seasons, and fishing in different 

 areas. It is difficult to detect areal or tem- 

 poral differences of significance in these data 

 probably because of the large inherent varia- 

 tion in daily catch rates of longline gear in the 

 vicinity of the islands (Iver senand Yoshida 1956); 

 e.g., during cruise 20, Charles H. Gilbert, 

 6 stations were occupied within 10 miles of 

 Christmas Island (between March 19 and April 5, 

 Appendix, table 17) and the catch rates varied 

 from 0.7 to 7. 1 yellowfin per 100 hooks. 



Japanese Longlining 



Data are again available for the longline 

 fishing operations of the Japanese in the vicinity 

 of the Equator (Nomura 1955-56). This informa- 

 tion is included in the Appendix, table 26. They 

 report the best average catch rate of 5.29 yellow- 

 fin per 100 hooks during July at 2°-5°N. , 160°- 

 152 °W. The poorest fishing (0.05 yellowfin per 

 100 hooks) was reported also during July but in 

 an area a little to the north and west (5°-Il°N. , 

 178°-174°W). The average catch rate for the 

 year was generally low. 



TAGGING PROGRAM 



At first consideration it would seem some- 

 what difficult to justify the expenditure of funds 

 and effort to carry out a tagging program in the 

 Line Islands, since the probability of recovery 

 of tagged fish in this region is extremely low. 

 Although occasionally Japanese vessels fish near 

 the islands, there is not a steady and intensive 

 fishery there. However, the potential value of 

 such a program is high, since the recovery of 

 only a few tags in this or other regions would 

 contribute greatly to our knowledge of the migra- 

 tory habits of yellowfin. Then too, tagging can 

 be carried out in conjunction with fishing survey 

 cruises which provide numbers of viable yellow- 

 fin in the process of determining abundance. The 

 possibility of recovery of a few of these fish. 



10 



