Fredy Esfrayn Tapia-Alave

Background: The reproductive cycle of Octopus mimus is regulated by environmental and hormonal factors, with photoperiod playing a key role in spawning induction and reproductive maturation. Understanding its underlying molecular mechanisms is essential for developing strategies to enhance controlled reproduction in aquaculture. Methods: We analyzed the expression of genes involved in the photoperiod-activated spawning induction cascade in the optic lobe and its downstream effects on the oviducal gland by performing transcriptomic analyses on females exposed to continuous light (24:0), which inhibits reproductive development, and a natural photoperiod, which induces spawning. The mRNA sequencing (RNA-Seq), quality control, gene annotation, and differential expression analyses were conducted using edgeR. Results: Spawning was completely inhibited under constant light, while 80% of control females spawned. Expression profiling revealed 89 downregulated and 34 upregulated genes in the optic lobe, and 178 downregulated and 237 upregulated genes in the oviducal gland (FDR < 0.05, |log2FC| ≥ 2), including key orthologs such as FMRFamide and myomodulin. Conclusions: These results show that the optic lobe integrates photoperiodic cues that modulate reproductive activation via a neuroendocrine cascade and coordinates spawning regulation through the oviducal gland, providing insights for improving reproductive control in aquaculture systems.

Octopus mimus aquaculture has gained relevance owing to its commercial potential; however, optimization of its reproductive and growth conditions in captivity requires further study. The objective of this study was to evaluate the reproductive conditioning, morphometric growth, and water quality of this species in a controlled system. To do this, adult O. mimus were selected and kept in circular tanks with controlled temperature, dissolved oxygen, pH, and salinity. Weight, total length (TL), mantle length (ML), and arm length (AL) measurements were made, in addition to monitoring seawater quality throughout the conditioning cycle. Paralarvae hatching productions were recorded, and Fulton’s condition index (k) was calculated to assess octopus health. The results showed that larger females produced more paralarvae, and that temperature significantly influenced the incubation period. The morphometric relationships between TL, ML, and LA were highly correlated, particularly in females. The seawater quality, with temperatures close to 22 °C, dissolved oxygen between 7.8 and 9.2 mg/L, 7.1–8.0 pH, and salinity around 35.3 PSU, was optimal for the welfare and reproduction of octopuses. This study provides keys to the effective management of O. mimus in aquaculture, with an emphasis on the importance of proper water quality management and the selection of larger broodstock.