The increasing demand for and reliance on plastics as an everyday item, and rapid rise in their production and subsequent indiscriminate disposal, rise in human population and industrial growth, have made the material an important environmental concern and focus of interest of many research. Historically, plastic production has increased tremendously to over 250 million tonnes by 2009 with an annual increased rate of 9%. In 2015, the global consumption of plastic materials was reported to be > 300 million tonnes and is expected to surge exponentially. Because plastic polymers are ubiquitous, highly resistant to degradation, the influx of these persistent, complex materials is a risk to human and environmental health. Because microplastics are principally generated from the weathering or breakdown of larger plastics (macroplastics), it is noteworthy and expedient to discuss in detail, expatiate, and tackle this main source. Macro- and microplastic pollution has been reported on a global scale from the poles to the equator. The major problem of concern is that they strangulate and are ingested by a number of aquatic biota especially the filter feeders, such as molluscs, mussels, oysters, from where it enters the food chain and consequently could lead to physical and toxicological effects on aquatic organisms and human being as final consumers. To this end, in order to minimise the negative impacts posed by plastic pollution (macro- and microplastics), a plethora of strategies have been developed at various levels to reduce and manage the plastic wastes. The objective of this paper is to review some published literature on management measures of plastic wastes to curb occurrence and incidents of large- and microplastics pollution in the marine environments.

The acceptability, digestibility and nutrient utilization of feeds containing cocoa husk were determined for tilapia Oreochromis niloticus fingerlings reared in a recirculation system. Three semipurified isonitrogenous diets formulated to contain 0, 100 and 200 g kg−1 of cocoa husk were fed to satiation three times daily. Although the feeds containing cocoa husk were acceptable to the fish, as indicated by their voracious consumption and positive weight gains, there were significant (P < 0.05) reductions in gross feed conversion efficiency with the cocoa husk feeds. Both apparent protein and dry matter digestibility were significantly (P < 0.05) reduced when 100 and 200 g kg−1 cocoa husk was fed. Specific growth rates of 3.51 and 3.34% per day, resulting from the two cocoa husk feeds, respectively, were significantly (P < 0.05) lower than growth rates of control fish. Apparent net protein utilization was not significantly affected (P > 0.05) by the 100 g kg−1 cocoa husk feed treatment. The consumption of the cocoa husk feeds could compensate for their low digestibility under acceptable fish yields and returns.

A preliminary investigation of length-weight relationship, condition factor and reproductive ecology of African pike fish, Hepsetus odoe, was conducted between June to August 2010 in Lake Eleiyele. A total of 90 samples of the fish species were caught by fishermen using gill nets. The results obtained showed that fish species had isometric growth pattern (contrary to negative allometry expected) with the growth exponent, b value of 2.64, that is not statistically different from 3 and with high statistical power of 0.866 when tested. The mean condition factor, K, was found to be 2.6, indicating that the fish species were in good condition in the study area. For reproductive biology, mean fecundity and gonadosomatic index were found to be 1349 eggs and 3.53% respectively. This study was necessary to fill the knowledge gap and provide information for management and conservation of the investigated species in the lake system. This study recommended that further research needs to be conducted because the sampling was carried out in the rainy season period and within a quarter of a year.

No abstract

Climate-induced floods are increasing in Africa. The need to evolve framework for adaptation to climate change impact (CCI) among flood-prone fish farmers necessitated this study. Based on availability, 60 farming active flood-experienced fish farmers were purposively selected from flood-prone (Gulu and Kibuku) regions in climate hotspot Uganda. These were assessed for CCI adaptation tendencies in their socioeconomics and farming operation/techniques (FOI) indices, CCI awareness, CCI adaptation strategies, and perceived required interventions (RIs) using structured questionnaire. Data were analyzed through descriptive and multivariate regression tools. Respondents were mostly male, adults, educated, Christian, married, medium-sized family, social group members, 1–5 years’ experience, medium-sized farms, and government trained. Income was 1.0–6.0 million Ugx/year. In FOI, semi-intensive culture system, use of rainwater plus groundwater, small-sized (< 0.5 ha) ponds, ponds possession of inlets and outlets, seasonal farming and mixed culture/farming dominated. Most respondents were aware of CCI, while erratic rainfall with floods and prolonged drought mostly impacted farming. AS-Adaptation Strategy were changed stocking time and livelihood diversification. Communication technology and social group’s membership enhanced adaptation, while inadequate awareness constrains adaptation. Respondents’ RI(s) were tree planting, irrigation and pond perimeter trenching. Gender, government training, farm size, water sources and presence of inlet and outlets in ponds (FOI) predicted adaptation (R = 0.802, R2 = 0.64, P < 0.05). Some socioeconomic, technical and awareness indices could assist CCI flexibility. However, the statistically significant predictors of adaptation, identified adaptive strategies, constraints to adaptation and required interventions could be integrated into a framework for effective CCI adaptation for sustainable fish farming in flood-prone scenarios.