Growth, mortality, exploitation rate and catch per unit effort (CPUE) of Mugil setosus in the central Mexican Pacific: An empirical approach

The grey mullet (Mugil setosus) is a valuable resource for coastal communities in the central Mexican Pacific; however, it is currently at the maximum sustainable yield. To update the biological and fisheries indicators for its management, growth, mortality, and catch-per-unit effort (CPUE) parameters for M. setosus in Nayarit were estimated for 2023, based on the analysis of 1,581 specimens from five fishing areas. Significant differences in size structure were found between areas (P < 0.05), with a range of 14.5-14.8 cm in total length (TL). The estimated growth parameters were L∞ = 40.5 cm, K = 0.43 yr-1, and t0 = 0.43 years. The total mortality rate (Z) was 0.63 yr-1, natural mortality (M) was 0.40 yr-1, and fishing mortality (F) was 0.22 yr-1. The overall exploitation ratio (E = 0.35) suggests that the stock is under-exploited at the state level, although zone V showed an E = 0.63, indicating fishing pressure above the optimal level. Using the Gomez-Munoz model, the estimated maximum CPU in March is 171 kg trip-1, with an average monthly production of 2,167 kg trip-1 per fishing unit. It is concluded that the majority of the catch (77.4%) exceeds the size at first maturity (25.4 cm Lm), which favors the sustainability of the stock.