16 



Albacore Ecology 



The Albacore Ecology Program was started at the Biological 

 Laboratory in 1960 to inquire into all aspects of the life history 

 of the Pacific albacore. Emphasis has been placed on inves- 

 tigations to determine whether albacore belong to more than 

 one subpopulation and if so whether these groups intermingle, 

 and to discover the nature of the albacore's migratory patterns. 

 These investigations are based on studies of spawning habits, 

 growth rates, differences in age and size composition of the 

 catch in American and Japanese commercial fisheries, and 

 other aspects of albacore biology. These fundamental studies, 

 designed to determine the extent of the Pacific albacore re- 

 sources and the effects of fishing on these resources, have 

 been spurred by the increase in intensity of the commercial 

 fishery during the past decade. 



Since July 1962, the Albacore Ecology Program has estab- 

 lished a field sampling station in American Samoa, continued 

 the study of albacore 'spawning habits, estimated the age and 

 size composition of the catch of the various Pacific albacore 

 fisheries from 1955 to 1959, and continued the collection and 

 study of juvenile albacore. These juveniles are found within 

 the broad area where earlier studies showed that albacore 

 spawned. 



The field sampling station was established in American 

 Samoa to document the rapid growth of the South Pacific alba- 

 core fishery. This is a longline fishery using vessels and 

 gear similar to those shown in figure 18. Measured by the 

 number of boats operating, fishing pressure for albacore in 

 the South Pacific fishery based at American Samoa has in- 

 creased approximately tenfold since inception in 1954. That 

 year the fishery's fleet of nine boats fished an area of approxi- 

 mately 80,000 square miles, and caught 270 tons. By 1963, 

 the fleet had increased to about 60 boats, the fishing grounds 

 extended over an area of some 8 million square miles (fig. 19), 

 and the catch was approximately 14,000 tons. The establish- 

 ment or expansion of albacore fisheries based in New Hebrides, 

 Fiji, and New Caledonia has further increased the rate at 

 which these resources are being exploited in the South Pacific. 



Figure 18. — The South Pacific albacore fishery uses 

 longline gear similar to that shown above. 



Laboratory personnel at the Samoan station have collected 

 data on the length, weight, and sex of albacore from each catch 

 landed by Japanese and Korean longline vessels at the island's 

 canneries. These data, supplemented by information on fishing 

 operations they obtained from the boat operators, will form 

 the basis for a study of the population dynamics of the South 

 Pacific albacore. 



In a study of albacore spawning habits in the South Pacific, 

 the Charles H. Gilbert made two surveys of the waters around 

 New Hebrides, New Caledonia, Fiji, EUice Islands, Tonga, and 

 Samoa. During the second survey (fig. 20), between October 7 

 and December 13, 1963, and designated Ahipalaha II,— plankton 

 nets and midwater trawls were towed to sample larval and 

 juvenile albacore, longline fishing was used to sample adults, 

 204 of which were caught. Female albacore taken on the 



3/. 



'Ahipalaha" is the Hawaiian name for albacore tuna. 



