SMALL-SCALE MOVEMENTS OF ALBACORE, THUNNUS ALALUNGA, IN 



RELATION TO OCEAN FEATURES AS INDICATED BY 



ULTRASONIC TRACKING AND OCEANOGRAPHIC SAMPLING 



R. Michael Laurs, 1 Heeny S. H. Yuen, 2 and James H. Johnson 3 



ABSTRACT 



Studies with ultrasonic tracking techniques and oceanographic sampling demonstrated that 

 oceanographic conditions play an important role in the local concentrations and movements of 

 albacore, Thunnus alalunga, in U.S. coastal waters. Albacore show a tendency to congregate in the 

 vicinity of coastal upwelling fronts, presumably to feed. They move away from the immediate area 

 when upwelling ceases and the upwelling front is no longer present at the surface. The movements of 

 albacore also appear to be related to the distribution of sea surface temperature, with fish spending 

 little time in water with surface temperatures cooler than 15.0°C. 



The average swimming speed for three fish tracked between 27.8 and 50 h was 1.6 knots (82.4 cm/sl 

 with each fish exhibiting slightly faster swimming speeds during hours of daylight than during hours 

 of darkness. 



The albacore, Thunnus alalunga (Bonnaterre), is 

 widely distributed in the Pacific Ocean. The single 

 subpopulation which is found in the North Pacific 

 (Otsu 1960) supports important surface commer- 

 cial fisheries in coastal waters off North America 

 and Japan and subsurface fisheries in the central 

 temperate Pacific. The species is also highly prized 

 by U.S. recreational fishermen. Passive tagging 

 methods have been used to study large-scale mi- 

 gratory patterns of albacore in the North Pacific 

 (Ganssle and Clemens 1953; Otsu 1960; Clemens 

 1961, 1963; Otsu and Uchida 1963; Laurs and 

 Nishimoto 4 ); however, information on small-scale 

 movements is scant. 



In order to examine the small-scale movements 

 of schools of albacore and evaluate the effects that 

 oceanographic conditions may have on the local 

 concentrations and movements of albacore in 

 coastal waters off the United States, studies were 

 conducted with ultrasonic tracking techniques 

 and oceanographic sampling. 



Tracking the movements of animals to which 

 ultrasonic transmitters have been attached is a 

 technique that has been developed over the past 

 two decades. This valuable technique has gained 



'Southwest Fisheries Center, National Marine Fisheries 

 Service, NOAA, P.O. Box 271, La Jolla, CA 92038. 



2 Southwest Fisheries Center, National Marine Fisheries 

 Service, NOAA, P.O. Box 3830, Honolulu, HI 96812. 



3 Northwest and Alaska Fisheries Center, National Marine 

 Fisheries Service, NOAA, 2725 Montlake Blvd. East, Seattle, 

 WA 98112. 



"Laurs, R. M., and R. N. Nishimoto. 1974. Joint NMFS-AFRF 

 albacore tagging study. SWFC Admin. Rep. LJ-74-47:63-81. 



Manuscript accepted October 1976. 

 FISHERY BULLETIN: VOL. 75. NO. 2. 1977. 



such wide application in recent studies of marine 

 fishes and Crustacea that it is more convenient to 

 cite a bibliographic source (Stasko 1975) than to 

 cite individual references. 



METHODS 



In the course of acoustic tracking studies, 

 environmental data commonly have been col- 

 lected for correlation with observed movements of 

 the animal. At times, small auxiliary craft have 

 been used for this purpose in support of the vessel 

 doing the tracking, but usually the collection of 

 environmental data has been done entirely from 

 aboard the tracking vessel, necessarily limiting 

 measurements to the ship's track. This study 

 represents a significant expansion of supportive 

 environmental data acquisition: for the first time 

 a major oceanographic research vessel and an 

 aircraft were coordinated with acoustic tracking 

 of fish. The ultrasonic tracking experiment in- 

 volved the use of the commercial albacore fishing 

 baitboat Linda on charter to the American 

 Fishermen's Research Foundation, the National 

 Marine Fisheries Service (NMFS) RV David Starr 

 Jordan, and a Coast Guard aircraft equipped with 

 sea surface temperature measuring equipment. 



Capture, Handling, and Tagging 

 of Albacore 



The capture of fish, tagging with ultrasonic 



347 



