MATURITY AND SPAWNING OF ALBACORE 



289 



j SURFACE -CAUGHT FISH (GILLNET a TROLLING 

 I LONGLINE- CAUGHT FISH 



uiifLL 



j ii i 



FISH LENGTH (CM.) 



Figure 2. — Sizes of nlbacore sampled in the North Pacific. 



Hawaiian Islands in the general area shown in 



figure 1. 



HAWAIIAN ISLANDS 



Ovaries from 56 fish ranging in length from 93.1 

 to 112.4 cm. (weight, 33 to 62 lbs.) were obtained 

 in 1955 and 1956 from landings of the Hawaiian 

 longline fishery (table 1, fig. 1). These fish were 

 captured within 20 miles of the main Hawaiian 

 Islands, mostly during the months of June to 

 September. A detailed description of this fishery 

 is given by June (1950) and Otsu (1954). These 

 albacore and those taken by the Toya Maru were 

 sampled at the auction markets of the United 

 Fishing Agency, Ltd., and the Hawaii Fishing Co., 

 Ltd., both in Honolulu. The ovaries were pre- 

 served in 10-percent formalin. Data obtained for 

 each fish were the date of landing, locality of 

 capture, fork length, and weight. 



CENTRAL EQUATORIAL PACIFIC 



The bulk of the samples from the central 

 equatorial Pacific was obtained from three areas: 

 (1) between the Equator and 7° S. latitude along 

 170° W. longitude; (2) between the Equator and 

 12° S. along 150° W. longitude; and (3) from the 

 general region of the Marquesas Islands, 132° W. 

 to 140° W. longitude (table 1, fig. 1). A total of 

 66 female albacore, all captured on longline on 

 POFI cruises, was sampled between February 

 1952 and February 1957; these fish ranged in 

 length from 84.6 to 104.8 cm. (weight, 29 to 54 

 lbs.). In general, sampling in this area was 

 sporadic both in space and in time. The method 

 of sampling the ovaries was similar to that 



described for the collection of gonads in the North 

 Pacific. 



DESCRIPTION OF THE GONADS 



TESTES 



The testes are paired, elongate organs sus- 

 pended by the mesorchium in the body cavity. 

 They are thin and ribbonlike in immature fish 

 but with advance in maturity, they develop into 

 somewhat flattened, whitish-yellow organs which 

 are relatively solid. Their products are collected 

 by a series of small ducts, vasa efferentia, leading 

 posteriorly to a larger duct, the vas deferens, 

 which opens to the exterior through the urogenital 

 orifice. 



June (1953) examined both the testes and 



ovaries in his study of the spawning of yellowfin 



tuna in Hawaiian waters but found that for this 



study "the testes were not suitable because no 



quantitative measure of their sexual products 



could be found that would provide reasonably 



accurate estimates of their relative stages of 



development." We found this to be true for the 



albacore also, and the testes were therefore merely 



designated in this report as immature or mature 



on the basis of their size and the presence or 



absence of milt. 



OVARIES 



The ovaries, like the testes, are paired, elongate 

 organs suspended from the dorsal wall of the body 

 cavity by the mesovarium. In immature fish, the 

 ovaries are ribbonlike (fig. 3), may measure as 

 little as 2 or 3 millimeters in diameter, and closely 

 resemble the immature testes in appearance. 



