autumn bonito
Refers specifically to bonito caught in autumn, which is considered less fatty than the spring catch (初鰹). Rare term; more commonly described as 秋の鰹.
Autumn bonito, also called modori-gatsuo, is lean and light in flavor.
Compound of 秋 (aki, 'autumn') and 鰹 (katsuo, 'bonito'). The reading がつお is a rendaku form of かつお.