Bonito or “katsuo” in Japanese are extensively caught by fishermen from Numazu, Shimizu, Yaizu and Omaezaki Harbours (all Shizuoka Prefecture). The main fishing areas are Shizuoka, Mie, Kochi & Miyazaki Prefectures.
It is also called “katsu” (Tohoku Region), “Honkatsuo” (Kyushu Island), “Magatsuo” (Shikoku and Kyushu Islands. N.B.: the same name designates another fish in other parts of Japan!), “Suji” (Yamaguchi & Wakayam Pref.).
It appears on the markets early Spring~Autumn as “sho gatsuo” (first bonito in Spring) and “modori gatsuo” (return bonito end of Autumn).
They are traditionally line-caught but nets have been used extensively in recent years.

credit to http://shizuokasushi.wordpress.com/seasonal-fishes-2-katsuo/