ABSTRACT: This study used Defense Meteorological Satellite Program (DMSP)/Operational Linescan
System (OLS) satellite images to classify and analyze the spatial and temporal variability of
nighttime fishing vessel lights in the Sea of Japan. OLS images can detect the powerful lights used to
attract squid. We examined DMSP/OLS nighttime visible images from 1994 to 1999. Fishing areas of
the Japanese common squid Todarodes pacificus were defined as the bright areas created by 2-level
slicing methods on DMSP/OLS images. T. pacificus fishing areas were mainly found along the east
coast of Korea, between Cheju and Tsushima Islands, around the Yamato Rise, along the coast of
Honshu, and in northern areas of the Sea of Japan. Using image classification and separability analysis,
we divided the Sea of Japan into 7 areas based on different temporal variability in squid fishing
area characteristics. The classification takes the potential northern and southern squid migration patterns
into account. One of the potential northern migration patterns formed along Honshu Island to
the north; another appeared along the east coast of Korea, northward through Yamato Rise. Southern
migration patterns were almost the reverse of northern migration patterns. These 7 classified areas
also correspond to the oceanographic characteristics of the Sea of Japan, i.e. a polar front at latitude
40°N, the inflow of the Tsushima Warm Current (TWC), and warm eddies. The use of remotelysensed
data demonstrated in this study offers a powerful and innovative way in which to determine
the migration and ecology of the Japanese common squid