SEASONAL DISTRIBUTION OF TUNAS AND BILLFISHES 



IN THE ATLANTIC 1 



By 

 JOHN P. WISE and CHARLES W. DAVIS 2 



ABSTRACT 



Charts of the Atlantic Ocean for each quarter of the year — January-March, etc. — 

 show the distribution of 10 species and groups of species fished by the Japanese 

 Atlantic longline fishery in the years 1956-68. These charts are based on detailed catch 

 and fishing effort data published by the Japanese Government. Quarterly average catch 

 per unit of effort was calculated for each 5° X 5° square, and contour lines were 

 drawn through equal levels of catch per unit of effort. The text explains the calcu- 

 lation and contouring processes in detail, and has a section of remarks and explanation 

 for each of the 10 species or groups. 



INTRODUCTION 



After World War II the Japanese longline 

 fishery for tunas and billfishes began to ex- 

 pand from the area of the home islands. By 

 1953 the fishery had reached about long 160 °W 

 in the eastern Pacific; by 1956 the Pacific 

 fishery extended at least to long 140 °W (Roths- 

 child, 1966), and the first commercial ven- 

 tures had begun in the Atlantic. Subsequent 

 expansion was rapid; in 1962 most of the 

 world ocean between lat 25 °N and 25 °S was 

 being fished by Japanese longliners. In 1969 

 the fishery had expanded so that most waters 

 between lat 40 °N and 40 °S were being fished 

 — the maximum north-south extension of the 

 fishery reached from nearly the Arctic Circle 

 to 55°S (Fisheries Agency of Japan, 1971). 



The Japanese Government has collected 

 detailed catch and effort data on this unique 

 fishery for many years and has published 



1 Contribution No. 211, National Marine Fisheries 

 Service, Southeast Fisheries Center, Miami Laboratory, 

 Miami, FL 33149. 



2 National Marine Fisheries Service, Southeast Fish- 

 eries Center, Miami Laboratory, Miami, FL 33149. 



most of the available information. The pub- 

 lished data for the Atlantic begin with the 

 inception of the Atlantic fishery in 1956; 

 worldwide coverage starts in 1962. These 

 data are of inestimable value from the point 

 of view of understanding the fishery and also 

 from the ecological standpoint by virtue of 

 the information they contain on the distribu- 

 tion and abundance of the species caught. 

 Many studies have been based on these data 

 — the earliest were those published by the 

 Nankai Regional Fisheries Research Labora- 

 tory on 1952 data (1954) and on 1958 data 

 (1959). Both covered only the Pacific, as did 

 Howard and Ueyanagi's (1965) atlas on the 

 distribution of billfishes. 



The data used here were taken from pub- 

 lications of the Nankai Regional Fisheries 

 Research Laboratory (Shiohama, Myojin, and 

 Sakamoto, 1965) and of the Research Division, 

 Fisheries Agency of Japan (Fisheries Agency 

 of Japan, 1965, 1966, 1967a, 1967b, 1968, 1969, 

 1970). Shiohama et al. reported on the long- 

 line fishery in the Atlantic for 1956-62; the 

 Fisheries Agency publications cover the fish- 

 ery in the world ocean for 1962-69. Among 



