Table 1. Classification of gonadal maturation stages (GMSs) in Indian mackerels

GMS	Male gonad morphology	Female gonad morphology
I	Testes are very small and threadlike and occupy half of the abdominal cavity.	Ovaries are white, band-like, and occupy less than half of the abdominal cavity.
II	Testes are thin, white, often covered with gray spots, and occupy half of the abdominal cavity.	Ovaries are white, band-like, and occupy half of the abdominal cavity.
III	Testes are white or pale and occupy the abdominal cavity.	Ovaries are yellow or pale and occupy half ⅔ of the abdominal cavity. Ova is not visible to the naked eye.
IV	Testes are pale, increased in length, and occupy the abdominal cavity.	Ovaries are yellowish-orange and occupy most of the abdominal cavity. Ova is not visible to the naked eye.