A New Perspective Of Mugil Liza: The Fast Growth In An Impacted Subtropical Bay

Mugil liza is one of the most important fishery resources in west margin of Southwestern Atlantic. Its northern population (northward of 23 degrees 40'S) is distributed along the Brazilian coast and, including the Guanabara Bay (GB, 22 degrees 50'S, 43 degrees 10'W). This study aimed to evaluate the ring formation in the sagitta to estimate the fish age and growth. Based on monthly samplings (2011-2013), 815 individuals were caught (285-815 mm TL), and a subsample of 299 otoliths were analyzed. The otoliths were embedded, cross-sectioned and read in terms of "annual"rings (macrostructural analysis). Then, they were analyzed in terms of daily rings (microstructural analysis) and the deposition of calcium carbonate (ultrastructural analysis). The comparison among the three methods revealed that five macro rings are formed in the first year. Ulterior to this diagnosis, back-calculation and growth models were simulated and tested to describe the growth in the first year and the general growth pattern. The ages varied from 0.63-up to 5 years-old, with a high variability of total lengths by ages. The von Bertalanffy growth model based on back-calculated lengths of Dahl-Lea best described the growth pattern. Mugil liza at GB presented sexual dimorphism in terms of growth, females being longer and older, and it was revealed a fast growth pattern. These findings reinforce the identity of a probable stock of M. liza at GB and change drastically the current knowledge their age and growth. The regulatory marks for the species must be reviewed, at least for GB. The current results evidence the need of current assessment and monitoring of fisheries resources, identifying the patterns of population groups. (C) 2021 Elsevier B.V. All rights reserved.