SKIPJACK IN HAWAII FISHERY 



299 



2 •■» -6 



I 2 3 7 n 15 19 23 



NUMBER Of LARGE / Small skipjack in THE CATCH 



Figure 15. — Size composition and catch per unit-of-efifort in the Oahu sljipjack fishery, 1952-53. 



NUMBER OF SMALL SKIPJACK IN CATCH (IN THOUSANDS) 



Figure 16. — Size composition and the number of sliipjack 

 caught in tlie Oahu fishery, 1952-5;i. 



their appear; nee in tlio catch during periods 5 and 

 7-9, 19.53 ( fig. 1'2) , they were associated witli fairly 

 large numbers of the nonmigi-atory small fish. 



The fact that the three migratory groups seem 

 to occur at different times suggests tliat there is 

 little overlap in their distribution, but the catch 

 records do not show this witli certainty, for (see 



Sources of Error) the average weight of fish in 

 the catch is a none too adequate index of size com- 

 position. The actual distribution of small skip- 

 jack is not defined by their appearance in the 

 catch. It is possible that during the periods when 

 the catch consists predommantly of large fish, 

 small skipjack are also available, but have been 

 rejected by the fishermen. In order to obtain in- 

 formation as to the quantity of small fish actually 

 present, a method such as maintenance of log- 

 books in which the fishermen could record their 

 observations of all fish sighted, whether fished or 

 not, would be requii-ed. 



The catch records provide little means of deter- 

 mining the relations between the four groups of 

 skipjack which seem to make up the population 

 exploited by the Hawaii fishei-y. It is quite 

 probable that the small fish in both the migi-atory 

 and semiresideut groups furnish recruits for the 

 season fish. The season fish of a given year may 

 be the large fish of the next year. The long-term 

 recoveiT of tagged specimens would appear to 

 offer the best means of ascertaining the relations 

 between these different groups of fish. 



