Surface Swarming of Euphausiids — Komaki 
435 
Fig. 1 . (a), Map showing partition of coastal areas of the Sea of Japan into 27 zones in order to 
observe the regional differences in euphausiid swarming. Zones 15 and 16 cover the Wakasawan area. (b), 
Fishing ground (shaded area) of Euphausia pacifica in the vicinity of Kinkazan. 
the coasts of Honshu, Kyushu, and adjoining 
small islands facing the Sea of Japan. 
The rate of response to the questionnaire 
was approximately 30%. To facilitate analysis 
of the replies, the coastline of the Sea of Japan 
was partitioned into 27 zones of 0.5° latitude 
or according to geographical features of the 
coasts (Fig. la ) . The fishermen’s unions were 
divided into 27 groups corresponding to these 
zones, so that geographical differences in the 
swarming, if any, could be detected. There 
were many responses suggesting interesting 
relationships between the swarming and en- 
vironmental factors (hydrographical, meteoro- 
logical, biological, and so on) . The author 
interviewed fishermen from important regions, 
on the basis of the results of the questionnaire, 
such as the Wakasawan area. Information that 
could be treated numerically (at least to some 
extent) was employed in the present paper. 
It was learned that, along the Pacific coast, 
the area around Kinkazan (Fig. lb) is the only 
place where the relatively stationary swarming 
is observed every year and the euphausiid fish- 
ery is maintained. The author visited this area 
in every swarming season and participated in 
the euphausiid fishing operation in order to 
make direct observations. No written question- 
naires were employed there. Reliable quanti- 
tative records of euphausiids fished from the 
Kinkazan district since 1953 were obtained 
from the fish market in Onagawa where al- 
most all the euphausiids from this fishing 
ground were landed, but no similar numerical 
data on the yield of euphausiids were available 
from the Sea of Japan. 
Water Temperature 
Among the important environmental factors 
governing distribution and behavior of the 
organisms, water temperature is not only the 
most important factor, but also is the one for 
which data can be obtained most easily. Ac- 
cordingly, these data were sought from the files 
of the hydrometeorological observations made 
by the various maritime and fisheries agencies 
listed below: 
Federation of Fishermen’s Unions of Miyagi Pre- 
fecture, Onagawa Branch. 1953-1959. Fisheries 
Statistics. 
Fukushima Prefecture, Fisheries Experimental Sta- 
tion. 1956. Data on oceanographic observations 
off Fukushima Prefecture, 1914-1939- 
Imperial Fisheries Research Office, Central Labora- 
tory. 1915-1950. Data on oceanographic surveys 
in the surrounding areas of Japan. 
Iwate Prefecture, Fisheries Experimental Station. 
