MATURITY AND SPAWNING OF ALBACORE 



299 



~ 0.6 



5 

 X 



< 



JAN 



FEB 



AUG 



SEP 



OCT 



Figure 10. — Maximum egg diameter for each of the 66 central equatorial Pacific albacore by date of capture. (Since 

 only the maximum egg diameter was recorded for most of the early developing ovaries, this measurement rather 

 than the modal diameter is used.) 



EVIDENCE OF SPAWNING 



The spawned-out or spent stage is recognized 

 by the presence of remnants of ripe eggs (residual 

 eggs in the process of resorption) in the lumen of 

 the ovary (Schaefer and Orange, 1956; Yuen and 

 June, 1957). A fresh, unpreserved spent ovary is 

 generally hollow and flaccid. In preserved speci- 

 mens, however, it may resemble any of the other 

 stages of maturity, even the early developing 

 ovary, depending upon how recently spawning 

 has occurred. Egg remnants were actually found 

 in ovaries in all stages of maturity from early 

 developing through advanced. 



In this study we classified the ovaries into 

 developmental stages without regard to the pres- 

 ence or absence of egg remnants. In figure 1 1 

 the maximum egg diameter for each of the Hawai- 

 ian and central equatorial Pacific albacore is shown 

 by fish size, and the ovaries which contained egg 

 remnants are indicated. No distinction was made 

 of the quantity of remnants in the ovaries, nor of 

 their stage of resorption. While the absence of 

 egg remants may not be accepted as proof that 

 the fish has never spawned, their presence con- 

 stitutes good evidence that spawning has oc- 

 curred (June 1953; Yuen 1955; Schaefer and 

 Orange, 1956; Yuen and June, 1957). Of a total of 

 56 Hawaii samples, 47 contained egg remnants, 

 indicating that these fish had spawned. Similarly 

 of 66 central equatorial Pacific ovaries examined, 



HAWAIIAN IS OVARY (NO REMNANTS) 

 HAWAIIAN IS. OVARY (WITH REMNANTS) 

 CENTRAL E0. PACIFIC OVARY (NO REMNANTS) 

 CENTRAL E0 PACIFIC OVARY ( WITH REMNANTS) 



85 



95 100 105 110 115 120 



FISH SIZE (CM ) 



Figure 11. — Relation between fish size and maximum egg 

 diameter. Ovaries with egg remnants are indicated. 



