1. The study of the biological characteristics of the fishes 

 which are the object of the fishery. 



2. Clarification of their relationships with ecological factors. 



3. Ascertaining the amount of the catch. 



4. Studying the changes in the size of the fish taken over a 

 number of years and the reasons for these changes. 



5. Deducing, on the basis of these data and the results of these 

 studies, the quantity of the resource, finding the proportion of the catch 

 to the resource, and determining the proper amount of fish to be caught. 



The studies which we are making of the tuna fisheries are, of 

 course, based on these orthodox research methods. On the one hand, 

 we carry out investigations of the environment aoid the biological char- 

 acteristics of these fishes at sea, enduring the tropical heat of the South 

 Seas and the stormy weather of northern waters. On the other hand, we 

 make morphological measurements of the catch in the fish markets in 

 the freezing early dawn, or we go for the purpose of collecting data on 

 fishing conditions to visit fishing boats, where we are often met with a 

 very cool reception, or even abused. Some of these data have already 

 been assembled and reported in the preliminary reports of investigations 

 of the resources by the Nankai Regional Fisheries Research Laboratory. 

 The results of our studies come out as Reports of the Laboratory or as 

 Progress Reports, and further reports will be published continuously in 

 the future. 



The basis for the construction of these charts of the average year 's 

 fishing conditions comprises the data from prewar operations of research 

 vessels from all parts of the country, which were recorded inReportNo. 1 

 of the Nankai Regional Fisheries Research Laboratory, and material which 

 has been gathered since the war from the reports of experimental and re- 

 search vessels and by interviewing personnel of commercial fishing boats. 

 For the purposes of this compilation, the cutoff date has been determined 

 as March 1952. However, where it appeared necessary, later data have 

 been added. It is regrettable that very few oceanographical data are pre- 

 sented, but this was unavoidable because the majority of the data were 

 gathered from ordinary commercial fishing vessels. 



It is anticipated that there will be various divergent views and 

 criticisms on the point of whether a work based on this amount of data 

 can be called representative of the average year, and also on the point 

 of whether it is proper to take 1 squares as the unit for fishing grounds. 



