exclusive category and their percentage by 

 volume of the total was estimated. The 

 number of each type of food item was also 

 recorded. In cases where the fish had 

 gorged itself on a large number of small 

 organisms the number was recorded as 

 "numerous. " 



For those species which were brought back 

 alive and released into the pond, mostly little 

 tunny and yellowfin, the only sampling data 

 available is an estimate of the weight of each 

 fish. As the estimates are considered reason- 

 ably accurate, they are included in the analysis 

 of the weight composition of the catch. 



CATCH AND CATCH RATE 



Data on the catch according to year, month, 

 and species are included in table 1. In the 

 following discussion our results will be compared 

 with those of Welsh (1949b), who conducted 

 trolling operations in the water s between Hawaii 

 and Kauai, including the present fishing area, 

 from March 1948 to December 1948 and from 

 February 1949 to June 1949. He used both the 

 Salpa and the Territorial Division of Fish and 

 Game's research vessel with fishing methods 

 essentially similar to ours. 



Table 1 shows that most of our catch 

 (96 percent) was comprised of four species: 

 skipjack, little tunny, dolphin, and yellowfin. 

 Frigate mackerel, wahoo, and jack made up the 

 remainder. The following tabulation of percent- 

 ages shows that the same four species formed 

 the bulk of the catch during the earlier period 

 (Welsh 1949b), but that little tunny were of much 

 greater relative abundance: 



1948-49 



(Welsh 1949b) 



8.4 

 63.9 

 18.4 



4.2 



3.7 



1.5 



Annual variation in catch rate for all species 

 combined and for each of the four principal 

 species is shown in figure 2. The comparison 

 between years is subject to error because of the 

 variation in number of lines used and because of 

 the variable seasonal coverage. 



2.4 



2 2 

 2.0 

 I.B 

 1.6 

 1.4 

 1.2 

 1.0 



3 .6 

 O 



D- 2 



I ° 

 u .8 



.6 



A 



.2 







.8 



.6 



A 



.2 







.8 



.6 



A 



.2 







ALL SPECIES 



SKIPJACK 



LITTLE TUNNY 



YELLOWFIN 



DOLPHIN 



1955 



Figure 2. --Average annual catch per hour's 

 trolling for all species combined and for the 

 four most abundant species in the catch over 

 the period 1951 to 1955. 



The apparent availability of fish to trolling 

 declined from a high of 2.46 fish per hour in 

 1951 to 0.97 in 1953, increased to 1.51 in 1954 

 and then decreased sharply to 0.77 in 1955. The 

 apparent general decline following 1951 persists 

 when the analysis is confined to comparable data 

 for the summer months. The general trend can 

 be attributed chiefly to a decreasing availability 

 of skipjack over the entire period and a low 

 availability of little tunny from 1953 to 1955. 

 These apparent changes, however, may well be 



