FISHERY BULLETIN: VOL. 69. NO. 4 



of fishing by Cuba and Venezuela. In 1968 the 

 combined landings of albacore by China and 

 South Korea were about 15,500 metric tons, 

 which was only 1000 tons less than the Japanese 

 catch for 1968. Recent estimates have placed 

 the Atlantic albacore catch for 1969 by China 

 and South Korea at 19,300 meti-ic tons. 



Worldwide demand for tuna is increasing 

 every year, and there is growing concern over 

 the condition and well being of Atlantic tuna 

 stocks. Catch rates of yellowfin tuna in the 

 longline fishery suffered severe declines in the 

 1960's. Wise (1968), Food and Agriculture 

 Organization (1968), Wise and Fox (1969), 

 Hayasi and Kikawa (1970), and others have 

 examined the problem and have concluded that 

 the longline stocks of yellowfin tuna have been 

 fished beyond their maximum capacity. 



This paper is an analysis of some aspects of 

 the population dynamics of Atlantic albacore 

 with comments on potential yields and stock size. 



AGE AND GROWTH 



There have been few studies on the age and 

 growth of Atlantic albacore. Distinct modes 

 appear in length-frequency distributions of al- 

 bacore samples from the Bay of Biscay surface 

 fishery, and these modes probably represent age- 

 groups. There is considerable disagreement, 

 however, over the assignment of absolute ages 

 to Atlantic albacore (Table 1). 



Le Gall (1949, 1952) worked with length fre- 

 quencies from the Bay of Biscay. He stated 

 that age-group I was less than 48 cm in length, 

 and that the first group that appeared in the 

 fishery was age-group II (56 cm). Figueras 

 (1957) used vertebrae from 67 fish in his anal- 

 ysis and concluded that 56- to 57-cm albacore 

 were 4 years old and that 17- to 18-cm albacore 

 were 1 year old. Yang (1970) estimated that 

 56-cm albacore were approximately 3 years old 

 based on results of his analysis of annular mark- 

 ings on scales. Otsu and Uchida (1959b), how- 

 ever, concluded from their study of vertebrae, 

 scales, and other hard parts of Pacific albacore 

 that there were no markings that could be con- 

 sidered age marks. 



I used data from the Bay of Biscay for 1967, 

 1968, 1969, and 1970 (Allain and Aloncle, 1968; 

 Philippe Serene and Jean-Claude Dao, Centre 

 National pour I'Exploitation des Oceans, person- 

 al communication) (Figure 2) as well as long- 

 line data (Figui-e 3) and estimated lengths at 

 age for Atlantic albacore (Table 1). 



Lengths at ages 1, 2, 3, and 4 wei-e estimated 

 by modes in length-frequency histograms from 

 Bay of Biscay samples. The first mode distin- 

 guishable in the length frequencies (Figure 2, 

 1968) is at approximately 44 cm, and I assume 

 that it represents age-group I. There is su])port 

 in the literature for the assignment of this ap- 

 proximate length to 1-year-old albacore. Otsu 

 and Uchida (1963) indicated that 30- to 35-cm 



Table 1. — Summary of age and growth investigations on Atlantic albacore. 



846 



