Seeds and feeds are among the most important inputs required for sustainable aquaculture industry development in any country worldwide. However, the value chain analysis of seeds and feeds in most developing countries including Tanzania has not been mapped, and the key actors are not identified and characterized. To address this knowledge gap, we mapped the fish seed and feed value chains in Morogoro, Dar es Salaam, Coast and Lindi regions in Tanzania, evaluated their performances, analyzed their contributions to aquaculture growth and finally assessed the critical factors impending aquaculture development before proposing appropriate strategies for upgrading. We found that the fish seed value chain comprised broodstock suppliers, seed producers, seed marketers, traders and fish farmers. Tilapia (Oreochromis sp.) and African sharptooth catfish (Clarias gariepinus) seeds produced were primarily sold to farmers at an advanced fry stage (1 to 5 g) at a price ranging from USD 0.09 to 0.13 and USD 0.22 to 0.27, respectively. The feed value chain consisted of suppliers, producers, importers, traders and fish farmers. The feeds produced were powdered, compressed and extruded pellets and granules sold at an average price of USD 2.50/kg. The seed and feed value chains in the four regions drive the aquaculture development and employ 137 and 109 people, respectively. The fish farming was mainly affected by insufficient seeds and feeds; inadequate extension services, inadequate technical skills in seed and feed production; limited farming equipment; insufficient capital and limited access to market. We propose increasing seed and feed production through collaborative research between researchers and the private sector, enhancing delivery of extension services to all fish farmers, providing fiscal incentives to hatchery and feed investors, organizing hatchery owners into associations, and undertaking marketing awareness campaign for aquaculture growth in the country for food, income and employment generation.

Octopus cyanea is a commercially important cephalopod in the Western Indian Ocean (WIO) region, but scientific information to inform management strategies for the species is limited. A study was conducted in 2014, 2015, 2017 and 2018 to investigate biological parameters including growth, mortality, exploitation rates and recruitment patterns in the sea around Mafia Archipelago, Tanzania. Virtual population analysis (VPA) indicated differential mortality between two sampling sites; the lowest and highest fishing mortality of F = 1.5yr-1 and F = 2.7yr-1 were observed in Bwejuu (Dorsal mantle length, DMT = 18-20 cm) and Jibondo (DMT = 8-12 cm) fishing villages, respectively. The maximum exploitation rate (Emax), which gives the maximum relative yield per recruit, was estimated at 0.380 and 0.379 for Jibondo and Bwejuu, respectively. The exploitation rates E 0.5, which corresponded to 50% of the unexploited stock relative biomass per recruit, were estimated at 0.248 for Jibondo and 0.247 for Bwejuu. These values differ greatly from the exploitation rates of 0.53 and 0.41 for Jibondo and Bwejuu, respectively, suggesting that the stock of O. cyanea is probably being overfished both in terms of yield per recruit and biomass per recruit. The stock-recruit pattern was observed to be continuous year-round, with the peak being between May and July. Since the peak in recruitment of both areas coincides with the south-east monsoon (SE Monsoon) and the level of maximum sustainable yield has been overshot, it is recommended that management plans are implemented that will reduce effort while increasing biomass, for example, implementing temporal octopus fishery closures at a village level.

The biodiversity of the western Indian Ocean is known mostly from inshore habitats, but little is known from the most extensive habitat of the region, the soft, unconsolidated sediments. Demersal trawl data from Kenya, Tanzania, Mozambique, South Africa and Madagascar were analysed, using average taxonomic distinctness in association with various environmental factors, to determine the biodiversity, the dominant genera that characterise the community assemblages and the areas where biodiversity was highest. A decreasing trend in biodiversity was observed from Kenya to Mozambique, including Madagascar, but South Africa had the highest average biodiversity. The continental slope was more biodiverse than the shelf, and biodiversity increased with depth to approximately 500 m, whereafter it declined. Depth and turbidity were the factors that best accounted for differences in community assemblages. The deep-water fish genera, Chlorophthalmus and Chaunax, dominated the slope assemblages, while the shelf communities were dominated by the shallow-water shrimp genera, Penaeus and Metapenaeus. Areas that have higher diversity, in general, included off Durban, South Africa, the Delagoa Bight off Maputo, Mozambique, and most of the area off southern Kenya. The information presented has improved the knowledge of soft sediment habitats in the WIO, thereby supporting decision-makers when deciding on planning options.