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The study calculated the Length-Based Spawning Potential Ratio (LB-SPR) for several species, including red grouper (Epinephelus morio), black grouper (Mycteroperca bonaci), gag grouper (M. microlepis), yellowtail snapper (Ocyurus chrysurus), lane snapper (Lutjanus synagris), hogfish (Lachnolaimus maximus), and white grunt (Haemulon plumierii). Data were obtained from the small-scale commercial fleet operating in the red grouper fishery on the Campeche Bank within the Yucatan Peninsula. Monthly records of total length (cm) from April 2017 to May 2018, totaling 10,182 fish, were collected from five fishing ports along the Yucatan Peninsula coast. Biological data, such as growth and reproductive patterns and exploitation parameters were gathered from scientific literature. The LB-SPR package on the R Core Team platform was utilized for analysis. Despite being the largest, groupers exhibited immaturity ( SL 50 < L 50 ) and low Spawning Potential Ratio (SPR). Red and black groupers showed particularly low SPR values (0.10 and 0.05, respectively), indicating a looming risk of local extinction. The gag grouper achieved the highest SPR value (0.26) among groupers, although it was very close to the minimum critical value (i.e., 0.20). Snappers, hogfish, and white grunt were generally captured in the adult state ( SL 50 > L 50 ). Yellowtail, hogfish, and white grunt displayed high SPR values (0.44, 0.72, and 0.98, respectively). Lane snapper had a low SPR (0.28) but fell within the range for maintaining satisfactory stock productivity, albeit with reduced yields. The findings emphasize the urgent need to adjust the current management framework for the red grouper fishery, focusing on improving fishing gear selectivity to address heightened pressure on both juvenile groupers and adult lane snapper. Implementing these measures is crucial to mitigate the risks of local extinction and population decline for each species. [ABSTRACT FROM AUTHOR]

Snappers are opportunistic carnivores with a leading role in energy flows between trophic interactions within tropical ecosystems. In the southern Gulf of Mexico, the few reported trophic-structure models are based on snapper stomach content data from other geographic regions (e.g. Atlantic coast of United States, northern Gulf of Mexico, Caribbean Sea and Brazil). To optimise the reliability of these models, we present new information on the diet composition of two commercially important species: lane snapper Lutjanus synagris and yellowtail snapper Ocyurus chrysurus. From January 2008 to 2009, the stomach contents of 1,074 L. synagris and 1,516 O. chrysurus were collected from three fishing sites off the northern coast of Yucatan, Mexico. Contents were analysed using frequency, number and weight of the identified prey species. A three-level, nested PERMANOVA analysis was used to assess differences between the potential prey and their biomass using the factors of snapper species, fishing site and climate season. Multidimensional scale (MDS) and SIMPER analyses were run to establish dissimilarity within the discriminating factors. The main food items found in the L. synagris diet were Brachyura, Penaeioidea and unidentified shrimps. Penaeioidea were the most abundant items in the O. chrysurus diet. Prey biomass analysis revealed a dissimilarity in diet composition between the two snapper species, as well as between fishing sites and climate seasons. The principal discriminatory prey categories were Brachyura, Penaeioidea, Osteichthyes, with Caridea and unidentified shrimps accounting for slightly smaller proportions. The results confirm the trophic position of these two sympatric snappers, showing that each plays a different trophic role in the ecosystem of the northern coast of the Yucatan Peninsula. [ABSTRACT FROM AUTHOR]