Octopuses are active predators that feed on a wide range of prey including crustaceans, fishes, and mollusks. They are important components of coral reef systems and support local and artisanal fisheries in the Gulf of México. Octopus insularis has been found to be one of the most relevant components in catches from the coral reef system of Veracruz in the southwestern Gulf of Mexico, and its role in the ecosystem requires assessment. To corroborate the morphological identification of O. insularis, six octopuses were identified by genetic methods. And to understand the trophic relationships between this octopus species and its prey, 394 octopuses caught during 2016 and 2017 by an artisanal fleet were sampled and their stomach contents analyzed. Results showed that crustaceans are the most frequently consumed group, with the genera Mithraculus and Etisus being the most important in the diet. Fishes, bivalves, and gastropods were identified as uncommon prey items in the diet. Their presence in the stomachs could be related to the movement of this octopus outside of the coral reef. Considering that our samples were of medium‐ and large‐sized individuals, cannibalism could be discarded for O. insularis in this size range in the Veracruz reef system. These findings suggest a generalist and opportunistic predation of O. insularis on the most abundant and available prey in the study area, namely the crustaceans. These represents an effective transfer of biomass from the low trophic levels to top predators in the coral reef system.

The common octopus of the Veracruz Reef System (VRS, southwestern Gulf of Mexico) has historically been considered as Octopus vulgaris, and yet, to date, no study including both morphological and genetic data has tested that assumption. To assess this matter, 52 octopuses were sampled in different reefs within the VRS to determine the taxonomic identity of this commercially valuable species using an integrative taxonomic approach through both morphological and genetic analyses. Morphological and genetic data confirmed that the common octopus of the VRS is not O. vulgarisand determined that it is, in fact, the recently described O. insularis. Morphological measurements, counts, indices, and other characteristics such as specific colour patterns, closely matched what had been reported for O. insularis in Brazil. In addition, sequences from cytochrome oxidase I (COI) and 16S ribosomal RNA (r16S) mitochondrial genes confirmed that the common octopus from the VRS is in the same highly supported clade as O. insularisfrom Brazil. Genetic distances of both mitochondrial genes as well as of cytochrome oxidase subunit III (COIII) and novel nuclear rhodopsin sequences for the species, also confirmed this finding (0–0.8%). We discuss our findings in the light of the recent reports of octopus species misidentifications involving the members of the ‘O. vulgaris species complex’ and underscore the need for more morphological studies regarding this group to properly address the management of these commercially valuable and similar taxa.

Mexican management plans currently consider just two octopus species in the official regulations, Octopus maya and Octopus vulgaris. However, the common octopus of the southwestern Gulf of Mexico has been recently identified as Octopus insularis, a species with unique biological and ecological characteristics. In accordance, we sampled O. insularis artisanal catches from the marine protected area of the Veracruz Reef System (VRS) between November 2017 and October 2018 and described its population structure and reproductive dynamics to provide basic biological information for the sustainable management of the species in the region. The 1,007 sampled octopuses ranged from 48 to 2,063 g in body weight (BW) and from 26 to 163 mm mantle length (ML). Most males were mature while the majority of females were immature. Although fishing closures in January, February and August precluded data gathering, most mature and juvenile specimens were registered in March and June respectively, thus, suggesting a year-long life cycle with spawning and recruitment peaks during winter and summer months respectively. Overall, sex ratios did not significantly shift from the expected 1:1, however males were significantly more abundant in December, which could be related to female spawning migrations to deeper waters. This was also supported by the generalized scarcity of mature and spent females in the catches. Males mature at a smaller size (590 g BW; 90 mm ML) than females (870 g BW; 108 mm ML). Although size at maturity is lower than the current minimum legal size for both sexes, most of sampled octopuses were smaller anyway, raising concern about the future sustainability of the fishery.

San Pedro River’s wetlands sustain trophic nets in the fluvial system, due to the high habitat availability, and space and temporal variations. In order to describe the relationship between environmental parameters and ichthyofauna, this study evaluated fish assemblages composition, distribution, abundance, density, biomass, richness species, diversity and equitability in the wetlands. Sampling considered three different sites and climatic seasons (dry, rainy and cold fronts). The physical and chemical parameters considered were dissolved oxygen, temperature, pH, water transparency and the depth. Fishes were caught with a shrimp net, after six minutes towings and were identified afterwards. A total of 1 049 organisms of 25 fish species were caught, two of which were exotic species: Oreochromis niloticus and Parachromis managuense. A total of 23 species were found at site I (with the highest density 0.23ind./m2), 17 at site II (0.23ind./m2) and 14 at site III (0.12ind./m2). The dry season had the highest species number with 21 species, followed by the rainy season with 17 species, and the cold season with five species. Similarly, the highest biomass (8.30g/m2) was found in dry season, followed by the rainy (2.16g/m2) and the cold seasons (0.03g/m2).

Considering seasons, highest density was found during the dry (0.436ind./m2), followed by the rainy (0.213ind./m2) and the cold (0.023ind./m2) seasons. The dominant density species during the study period, according to the quadrants graphic of Olmstead-Tukey were: Petenia splendida, Vieja heterospila, Vieja synspila, Dorosoma petenense and Astyanax aeneus. There were significant differences in the species richness among sites. Temperature, depth and transparency showed differences among the seasons. The canonical correspondence analysis indicated that fish distribution was governed by environmental parameters during all seasons. In terms of fish abundance and composition, environmental parameters play an important role showing spatial and temporal differences in the ecosystem, this could be explained with the fact that most of young fishes have a movement behavior to the wetlands, searching refuge and feed during the dry season. Considering the diversity indexes variation, it may be concluded that San Pedro River’s wetlands correspond to a system where the ichthyofauna composition fluctuates spatial and seasonally.