Estimation of age, growth, and length at first maturity of the round herring Etrumeus acuminatus (Gilbert, 1890) on the western coast of Baja California Sur, Mexico

In Mexico, the round herring Etrumeus acuminatus is caught along with other small pelagic fishes of the Western Baja California Sur coast (WBCSC) and Gulf of California. This species has a discontinuous distribution on the eastern margin of the Pacific Ocean, and its population structure and dynamics are unknown. In this study, we evaluated the direct determination of age using otoliths, estimated length at first sexual maturity (L50), and individual growth parameter determination of round herrings caught off the WBCSC. A total of 731 specimens were collected through monthly biological sampling from 2012 to 2022. Age-length data were obtained from 617 otoliths. The growth was isometric (b = 3); however, the differences in the length-weight relationship were significant between sexes (F = 7621, P < 0.05). Up to seven age groups were identified (0 ± 6). The L50 and individual growth parameters were estimated using a multimodel approach. The Lysack (1979), White et al. (2002), Brouwer & Griffiths (2005), and logistic models showed statistically solid support for L50 estimation in both sexes. The von Bertalanffy model provided the best fit for the data to describe individual growth in both sexes. Significant differences between sexes were detected in the L50 estimates (P < 0.05). However, the differences in growth parameters between sexes were not statistically significant (P > 0.05).