REPRODUCTIVE DYNAMICS AND POPULATION STRUCTURE OF OCTOPUS INSULARIS FROM THE VERACRUZ REEF SYSTEM MARINE PROTECTED AREA, MEXICO

Abstract

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.