Nigeria is the most populous black nation in the world, with an estimated population about 150 million people. Its citizens as at the end of 2012 have a projected fish demand of 2.66 million tonnes of fish. Fish suppl...Nigeria is the most populous black nation in the world, with an estimated population about 150 million people. Its citizens as at the end of 2012 have a projected fish demand of 2.66 million tonnes of fish. Fish supply within the said period was 1.32 million tonnes. This figure was made up of 0.7 million tonnes from importation and 0.62 million tonnes from both artisanal and aquaculture. Of the local production aquaculture contributes only 200 000 tonnes. Studies have shown that fish catch from the wild has reached its maximum production limit and production from this area is currently on the decline. Nigeria has about 1.75 hm2 of suitable sites for aquaculture development. Aquaculture production for 2012 was a meager 200 000 tonues. Aquaculture though a veritable means is faced with a lot of constraints ranging from government＇s wrong focus on industrial fisheries instead of aquaculture, poor policy formulation and non-implementation fisheries development programmes among others. In spite of these constraints, there were also the following aquaculture investment opportunities such as production of fishing equipment, establishment of modern fish farms, shrimp fishing, fingerling production, table size fish production, brood stock production, fish feed production, ornamental fish farming, production system design and construction, capacity building in project management, packaging and branding.展开更多
This study was conducted in Akwa Ibom, Bayelsa and Delta States of the Niger Delta, Nigeria. It examined the level of adoption of aquaculture technologies by Fadama Ⅲ beneficiaries and assessed the differences in ado...This study was conducted in Akwa Ibom, Bayelsa and Delta States of the Niger Delta, Nigeria. It examined the level of adoption of aquaculture technologies by Fadama Ⅲ beneficiaries and assessed the differences in adoption levels on sate basis. Five fish farmers were randomly selected on multiple stage bases from 18 Fadama Users＇ Groups （FUGs） amounting to 90 farmers as the sample size for this study （n=90）. Structured questionnaire was used to elicit information from respondents. Data collected were measured using descriptive and adoption Sigma method analysis. Results obtained revealed that of the 12 selected aquaculture based technologies recommended by Fadama Ⅲ, the ratio of adoption skills ranged from 1 high： 7 medium： 5 low. The adoption levels followed a sequence of earthen ponds preparation being the highest, and stocking density techniques being the lowest. The overall adoption level was 4.20 which implied that the aquaculture farmers were categorized as medium adopters using the Sigma method scale. It was recommended that farmers with adoption levels at medium and low ranges should be focused upon with more teaching sessions by community facilitators and that other extension workers should emulate the strategies used by Fadama Ⅲ in developing farmers.展开更多
水生植被和藻类作为湖泊生态系统的主要初级生产者,对湖泊生态系统具有重要作用。在气候变化和人类活动的双重作用下,湖泊富营养化加剧,水生植被退化,藻类水华频发。开展湖泊水生植被群落和藻类水华的长期观测可为湖泊生态系统水生植被...水生植被和藻类作为湖泊生态系统的主要初级生产者,对湖泊生态系统具有重要作用。在气候变化和人类活动的双重作用下,湖泊富营养化加剧,水生植被退化,藻类水华频发。开展湖泊水生植被群落和藻类水华的长期观测可为湖泊生态系统水生植被修复和藻类水华管控提供决策依据。本研究以太湖流域浅水湖泊长荡湖为研究区,基于1985-2021年的Landsat 5和8卫星数据,利用VBI(vegetation and bloom indices)草藻分类算法,开展了浮叶/挺水植被、沉水植被和藻类水华长时序时空演变分析。结果表明:36年来,长荡湖水生植被(包括浮叶/挺水植被和沉水植被)都呈现显著下降趋势,其中沉水植被下降趋势尤为明显,沉水植被从湖中心向岸边逐步退化,其覆盖度从1985年的75%下降至2021年的不足21%;自2011年起,长荡湖水生植被优势生活型从沉水植被转变为浮叶/挺水植被;2010年首次监测到水华发生,2020年和2021年连续两年均监测到湖中心有大面积水华。基于湖泊围网面积和气象数据分析发现,围网拆除是水生植被退化和优势生活型转变的主要因素。展开更多
文摘Nigeria is the most populous black nation in the world, with an estimated population about 150 million people. Its citizens as at the end of 2012 have a projected fish demand of 2.66 million tonnes of fish. Fish supply within the said period was 1.32 million tonnes. This figure was made up of 0.7 million tonnes from importation and 0.62 million tonnes from both artisanal and aquaculture. Of the local production aquaculture contributes only 200 000 tonnes. Studies have shown that fish catch from the wild has reached its maximum production limit and production from this area is currently on the decline. Nigeria has about 1.75 hm2 of suitable sites for aquaculture development. Aquaculture production for 2012 was a meager 200 000 tonues. Aquaculture though a veritable means is faced with a lot of constraints ranging from government＇s wrong focus on industrial fisheries instead of aquaculture, poor policy formulation and non-implementation fisheries development programmes among others. In spite of these constraints, there were also the following aquaculture investment opportunities such as production of fishing equipment, establishment of modern fish farms, shrimp fishing, fingerling production, table size fish production, brood stock production, fish feed production, ornamental fish farming, production system design and construction, capacity building in project management, packaging and branding.
文摘This study was conducted in Akwa Ibom, Bayelsa and Delta States of the Niger Delta, Nigeria. It examined the level of adoption of aquaculture technologies by Fadama Ⅲ beneficiaries and assessed the differences in adoption levels on sate basis. Five fish farmers were randomly selected on multiple stage bases from 18 Fadama Users＇ Groups （FUGs） amounting to 90 farmers as the sample size for this study （n=90）. Structured questionnaire was used to elicit information from respondents. Data collected were measured using descriptive and adoption Sigma method analysis. Results obtained revealed that of the 12 selected aquaculture based technologies recommended by Fadama Ⅲ, the ratio of adoption skills ranged from 1 high： 7 medium： 5 low. The adoption levels followed a sequence of earthen ponds preparation being the highest, and stocking density techniques being the lowest. The overall adoption level was 4.20 which implied that the aquaculture farmers were categorized as medium adopters using the Sigma method scale. It was recommended that farmers with adoption levels at medium and low ranges should be focused upon with more teaching sessions by community facilitators and that other extension workers should emulate the strategies used by Fadama Ⅲ in developing farmers.
文摘水生植被和藻类作为湖泊生态系统的主要初级生产者,对湖泊生态系统具有重要作用。在气候变化和人类活动的双重作用下,湖泊富营养化加剧,水生植被退化,藻类水华频发。开展湖泊水生植被群落和藻类水华的长期观测可为湖泊生态系统水生植被修复和藻类水华管控提供决策依据。本研究以太湖流域浅水湖泊长荡湖为研究区,基于1985-2021年的Landsat 5和8卫星数据,利用VBI(vegetation and bloom indices)草藻分类算法,开展了浮叶/挺水植被、沉水植被和藻类水华长时序时空演变分析。结果表明:36年来,长荡湖水生植被(包括浮叶/挺水植被和沉水植被)都呈现显著下降趋势,其中沉水植被下降趋势尤为明显,沉水植被从湖中心向岸边逐步退化,其覆盖度从1985年的75%下降至2021年的不足21%;自2011年起,长荡湖水生植被优势生活型从沉水植被转变为浮叶/挺水植被;2010年首次监测到水华发生,2020年和2021年连续两年均监测到湖中心有大面积水华。基于湖泊围网面积和气象数据分析发现,围网拆除是水生植被退化和优势生活型转变的主要因素。
