Feeding habits and diet composition of Octopus cyanea (Gray, 1849) in Zanzibar waters, Tanzania

Abstract

The octopus fishery in Zanzibar is an essential activity of coastal communities. To assist with developing fisheries management plans, baseline information on the feeding of Octopus cyanea (Gray, 1849) was collected in relation to sex and maturity stages. The feeding habits and diet composition of 543 O. cyanea were studied over a period of 12 months at Paje, Kizimkazi, Chwaka Bay and Nungwi. Samples at each site were collected on two days per month during spring tide. Digestive tract contents revealed that O. cyanea preyed on 36 species of crustaceans, molluscs and fishes, with crabs a major prey item. The number of prey species in a single stomach ranged from one to six. O. cyanea in Zanzibar is therefore a generalist predator with a mixed diet. The octopus gonadosomatic index (GSI) indicated a peak breeding season in June to October, which correlated with low prey consumption. Mature octopuses ingested a small amount of food from mainly small sessile prey. Females consumed less food than males of similar maturity stages, suggesting that they ate less or had higher digestion rates. The information is useful for developing fisheries management plans for the octopus fishery in Zanzibar.