Reproductive biology of Atlantic chub mackerel (Scomber colias) was studied based on samples from commercial catches in M'diq Bay, Morocco. Females predominated in the total catch (54%), their size at first maturity being 19.19 ± 0.43 cm TL. A minimum landing size (MLS) of 21 cm is suggested. The oocyte size frequency distribution and histological analysis confirmed that S. colias is a species with an indeterminate fecundity. The batch fecundity was estimated as 18,452–131,642, with a mean of 60,022 oocytes. The relative batch fecundity was 157–360, with a mean of 279 eggs g−1.
