Habita 



The life history of this species is known, but in Formosa it is not possible to acquaint 

 oneself with it. In general this species is rather rare in Formosa, an occasional one being landed 

 at Takao. It is thus not an important species. It appears that in the waters off eastern Formosa 

 it is taken only extremely rarely and is not an objective of the harpoon fishery but is taken by the 

 longline fishery. According to conversations with experienced fishermen, when this species is 

 hooked and dies in the water it immediately floats to the surface and does not sink like the other 

 spearfishes. 



II. ECOLOGY 



A. Migrations 



There are a great many things that are not known about the habits of the spearfishes. 

 Here I will deal chiefly with the migrations of the spearfishes in Formosan waters. 



In the conduct of such a special sort of fishery as the harpoon fishery, the habits of the 

 spearfishes are skillfully utilized. When the wind and waves are high, the spearfishes rise to 

 the surface of the water and swim there with their dorsal fins projecting. According to experi- 

 enced fishermen, this surfacing of spearfish is most often seen when the current and the wind are 

 running in exactly opposite directions, and no fish are seen at the surface at all when the current 

 and the wind are running in the same direction. It is said that in many cases the direction in 

 which surfaced spearfish swim coincides with the wind direction and runs counter to the direction 

 of the current. However, this does not nnean that when such conditions prevail the spearfishes 

 are at the surface all of the time; it is said that they come up temporarily, and that when they 

 begin to come up they all come up at once. 



In the waters off eastern Formosa, where the Japan Current passes, the current flows 

 north with a slight easterly connponent. From October to March the northeast monsoon blows 

 quite continuously in a direction just opposite to that of the current, and if we are to adopt the 

 results of the fishermen's experience, this sea area must be said to be a well-suited ground for 

 spearfish fishing. 



Judging from the results of several years of commercial fishing experience, in the winter 

 the normal distribution of atmospheric pressures breaks down and weak lows arise or pass 

 through the waters north of Formosa, and at such times the monsoon stops blowing, there are 

 light southerly winds, and the sea surface becomes calm and the sky clear. In such weather the 

 commercial boats stay in port and give up going fishing. Such weather ordinarily continues for 

 1 to 3 days, and as the lows move away and dissipate, strong high pressures appear in the 

 Mongolian region, and with the return to normal of the distribution of atmospheric pressure, 

 the wind direction changes suddenly and the monsoon begins to blow strongly. When there are 

 these sudden shifts in the wind direction, the spearfishes come to the surface in the greatest 

 numbers and many specimens much larger than those ordinarily caught are taken, the white nnarlin 

 appearing to be most numerous among them. The fishing boats usually leave port before dawn 

 and return in the evening, but in cases where the boats have failed to go out fishing because the 

 light southerly winds were blowing before dawn (these winds are called " maji" or " maze "), if 

 there is such a sudden change in the weather they will go out at any hour and it not infrequently 

 happens that they make big catches. 



The spearfishes are probably present in Formosan waters at all times of the year, but 

 there is no doubt that the fact that they are particularly abundajit at certain seasons is due in 

 large measure to seasonal changes in oceanographic conditions. However, the fact that they 

 remain throughout approximately half of the year, forming dense schools in the waters off eastern 

 Formosa, is difficult to account for simply by the direct effect of oceanographic changes. 



The fishing season for spearfishes begins in the south and moves gradually north, usually 

 ending around March or April in the vicinity of Hokasho. We have the following oceanographic 

 data for this area: 



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