抄録
The writer examined the stomach content of the Pacific mackerel, Pneumatophorus japonicus (HOUTTUYN), caught by purse seiners on its winter quarter off the southern districts of Niigata Prefecture in late February, 1958. The examination led to the finding that nearly half of the examined fish contained considerable quantities of sea bottom sediments such as gravels, sands, silts, shell fragments and tubes of annelid worms mixed with bait animals (Table 1). Taking into account the condition with which these sediments were included in the stomach as well as their size composition and sinking velocity through sea water (Figs. 1 and 2), it is supposed that the sediments were possibly taken by the fish skimming the sea bottom in search of food. The principal foods of the fish were composed of euphausiid, Exphausia pacifica HANSEN, pearlsides, Maurolicus japonicus ISHIKAWA, and a few species of copepods, in them the euphausiid was volumetrically dominant Finally, a short discussion was made concerning the aspect of the habit of this shrimp-like crustacean, suggesting that it may be an inhabitant of the sea floor, actually inhabiting on the bottom, during the daytime.
