2.100 



1,800 



_ 1.500 



> 

 o 



IL 



o 



Q 1,200 



< 

 w 



3 



o 



X 



a 



z 



o 



UJ 



u. 



900- 



600- 



300 - 



PRESENT STUDY 



• YABEM954) 

 ▲ YOSHIDA (1966) 

 RAJUM964) 

 JOSEPH (1963) 



450 



— i — 

 550 



650 

 FORK LENGTH (MM.) 



750 



850 



Figure 6. — Fork length -fecundity relation for skipjack tuna. Present data and regression line are shown, together with 

 the data of Yabe (1954) and Yoshida (1966) and the regression lines of Raju (1964) and Joseph (1963). 



Raju (I960) described an ovary of a skipjack 

 tuna (collected in the Indian Ocean) that was 

 infested with 68,200 larval nematodes; all the 

 ova in the left ovary had been destroyed ex- 

 cept the small transparent ones along the 

 periphery. 



Maybelle Chitwood (personnal communica- 

 tion) identified two taxa of nematodes from 

 the ovaries of skipjack tuna caught in the 

 eastern tropical Atlantic, western tropical 

 Atlantic, and off New York. One was Philo- 

 metra sp. (suborder Camallanata), and the 

 other was a species of the superfamily 

 Spiruroidea (suborder Spirurata). She re- 

 ported that members of the Camallanata use 

 a copepod or other marine invertebrate as an 

 intermediate host; it is possible that marine 



spirurids use the same intermediate host as 

 Philometra . Chitwood also stated that mature 

 fertilized female nematodes are probably pre- 

 sent in the ovaries. The embryos presumably 

 are released when the fish spawns. 



AC KNOWLE DGME NTS 



James Joseph of the Inter-American Trop- 

 ical Tuna Commission and Brian J. Roths- 

 child of the Bureau of Commercial Fisheries, 

 Honolulu, Hawaii, critically reviewed the man- 

 uscript. Eric Kwei of the Ministry of Agri- 

 culture, Fisheries Division, Tema, Ghana, and 

 Craig J. Orange and Javier Barandiaran of 

 the Inter-American Tropical Tuna Commis- 

 sion helped procure material. 



15 



