temperate waters in their second year, and enter the eastern 

 Pacific catch in large numbers in their third year. Many 

 cross the Pacific to mingle in the catch off Japan, where 

 they spend several years ; eventually the older fish perform 

 another migration, returning to subtropical and tropical 

 waters to spawn. The albacore is a long-lived fish. It does 

 not reach sexual maturity until its sixth year. The fish that 

 migrate to the south are large and old. 



The albacore taken in the Hawaiian longline fishery are 

 unlike those caught anywhere else; they are on the average 

 considerably larger than those in any other North Pacific 

 fishery. They have reached record weights (93 pounds is 

 the largest; albacore caught in the eastern Pacific fishery 

 average about 14 pounds). These fish seem to represent 

 the large, old segment of the population that has entered 

 .subtropical waters to spawn. That the albacore do spawn 

 near Hawaii has been borne out by other studies. Although 

 tuna eggs cannot be distinguished by species, many of the 

 postlarvae can. Identification is especially simple for the 

 albacore postlarva, which develops a flattened haemal spine 

 on the first caudal vertebra. This unique characteristic 

 appears in specimens as short as 2 centimeters, about three- 

 fourths of an inch. Discovery of these small fish in Hawai- 

 ian waters has shown that the albacore spawn nearby. 



Little Albacore 

 Very few of the juvenile albacore have been taken 

 by the scientists' nets. More have been found in the 

 stomachs of billfishes. During this reporting period, Howard 

 O. Yoshida has studied juvenile albacore collected from 

 the stomachs of billfishes from the Honolulu fresh-fish 

 market. From 3, .348 stomachs collected between June 1962 

 and December 1964, he took 23 juvenile albacore. (Stomachs 

 contained far more skipjack — 696 ; these form the basis of 

 another study.) Most of the billfish, 2,791, were striped 

 marlin (Makaira audax), which weigh from 10 to 325 

 jtounds. 



By measuring the length of the vertebral column of his 

 specimens, Yoshida was able to estimate the standard 

 length of the intact fish. Using these lengths and his 

 information on the date of the landing of the billfish, he 

 estimated the growth rate of the very young fish, a matter 

 upon which very little data exist. His estimate is that the 

 young albacore grow about 3 centimeters (a little more than 

 an inch) a month during most of their first year of life 

 (fig. 15). He was able to estimate the date of spawning, 

 which appears to begin late in May and to last several 

 months. 



It is only rarely that fish smaller than 40 centimeters 

 (15.6 inches) enter the albacore fisheries. Hence Yoshida's 

 work corroborates other information that would place the 

 North Pacific albacore in subtropical or tropical waters dur- 

 ing the first year of its life. Where its spawning grounds are 

 centered and how extensive they are, is unknown. Some 



JUNE JULY AUG. SEFT. OCT. NOW DEC. JAN. FEB. MAR. 

 FIGURE 15. The juvenile albacore grows about 3 cenli- 

 melers (a little more than an inch) a month in Hawaiian 

 **alers during ihe fir!st vear of its life. 



21 



