Spawning season, size at first maturity, and fecundity in chub mackerel (Scomber colias Gmelin, 1789) from the Atlantic coast of Morocco

Scomber colias has become an increasingly important commercial species in the Atlantic waters of Morocco. However, the fishing efforts applied to this species inversely influenced their stock biomass. This investigation aimed to determine the spawning season and to study the reproductive patterns of Scomber colias in the Atlantic coast of Morocco based on macroscopic and microscopic approaches. For this, a total of 1225 individuals were sampled in the fishing port of Agadir Bay from May 2017 to May 2018. The overall sex ratio was 1:0.49 females to males. The highest gonadosomatic index (GSI) values were recorded from December (1.47 +/- 1.02 for females and 1.65 +/- 1.56 for males) to February (1.36 +/- 1.06 for females and 1.94 +/- 1.39 for males), with the peak in January (3.16 +/- 3.00; 2.77 +/- 2.45) which supposed to be the spawning season. The high values of Hepatosomatic index (HSI) were obtained from September (1.47 +/- 0.31 for females and 1.46 +/- 0.30 for males) to November (1.63 +/- 0.35 for females and 1.59 +/- 0.34 for males) and from February (1.90 +/- 0.48 for females and 1.43 +/- 0.36 for males) to April (1.40 +/- 0.49 for females and 1.29 +/- 0.33 for males) with the peak in March (2.33 +/- 0.7 for females and 2.30 +/- 0.69 for males). The condition factor (K) showed low values that fluctuated between (0.67 +/- 0.11) and (0.81 & PLUSMN; 0.06) for females and between (0.69 & PLUSMN; 0.06) and (0.81 & PLUSMN; 0.06) for males. The size at first maturity recorded was Lm = 21.08 cm for females and Lm = 20.82 cm for males. The absolute fecundity varied from 41325 to 494500, while the relative fecundity varied from 238 to 1020 oocyte/g. The sexual maturity was assessed by histological analysis. Those biological data are indispensable for the assessment of the stock of this species.(c) 2022 Elsevier B.V. All rights reserved.

Automated summary

Scomber colias has become increasingly important commercially in the Atlantic waters of Morocco, but fishing efforts have negatively impacted its stock biomass. This study aimed to determine the spawning season and reproductive patterns of Scomber colias in the Atlantic coast of Morocco using macroscopic and microscopic approaches.