Understanding the Impact of Emerging Contaminants to Biological and Fishery Aspects of Octopus cyanea in Tojo Una‐una Waters

Octopus cyanea is a species of octopus caught in Indonesian waters, including Tojo Una‐una waters, Central Sulawesi. This research explores the environmental conditions in relation to biological and fishery aspects of O. cyanea . In this study, we used four monthly environmental parameters: chlorophyll‐a, dissolved oxygen, salinity, and temperature (temp) at 0.5 m; the biological aspects of gonadal maturity stage, gonadosomatic index (GSI), and population parameters from February to August 2021; and the fishery aspect of catch per unit effort (CPUE). The impact of environmental variables on biological and fishery aspects of O. cyanea was analyzed using a simplified method of the Generalized Additive Model (GAM). The results indicated that salinity and temperature had a high correlation with GSI patterns both in female and male, and chlorophyll‐a had a high correlation with CPUE. Moreover, the male GSI value showed a high trend in February–March and low in August. Meanwhile, in females, GSI was high in February‐March and lower in June. The size (by weight and mantle length) at first capture of males was smaller (519 g and 12 cm) than females (1193 g and 16 cm). Weight at first maturity for males was 605 g and for females 1086 g, while fully mature males were found at 1312 g and females at 2311 g. Length at first maturity for males was 10–11 cm and for females 11–12 cm, and fully mature at 12 cm for males and 13 cm for females. The female's asymptotic length ( L ∞ ) was 22 cm, while the male's was 18 cm. The female's asymptotic weight ( W ∞ ) was 6813 g, while the male's was 3628 g. The maximum age ( t max ) of female was 2 years, while male was more than 2 years. The fishing mortality and exploitation rate of males was greater than females. Management measures are required since the exploitation rate resulted in full exploitation, particularly for males. Closing the fishing season for at least 3 months, from May to July, is the suggested management strategy.