Replication Data for: Assessment of the Efficiency of Fish Marketing Channels in the Lake Kainji Inland Fisheries and along Nigeria-Niger Border

Improvement of food, nutritional security and poverty reduction in Africa can be addressed through better integration of intra-regional fish trade into the nation-state policy agenda. Data crucial to the development of regional fish trade needs to be obtained. However, there is paucity of information on market structure, products and value of fish trade along regional borders in Africa. This study therefore investigated fish marketing structure, the marketing actor’s characteristics, fish distribution channels, market profitability and efficiency along the Nigeria-Niger border and Lake Kainji inland fisheries. A multistage sampling procedure was used in the selection of respondents for this study. Random sampling was carried out in selecting four states Sokoto, Katsina, Jigawa and Yobe along the Nigeria-Niger border, Niger state was purposively selected based on its location in the Lake Kainji inland fisheries. Data was collected from 150 respondents in each of the states comprising 50 producers, processors and marketers each, amounting to 750 with the use of a structured questionnaire. Data on socio-economic characteristics, marketing operations, marketing channel, market structure, profitability and trade flow were obtained. Data were analysed using descriptive statistics, budgetary indices, gini coefficient, linear regression, Stochastic production frontier model and ANOVA at α 0.05. There was a predominance of male producers, marketers and processors in Katsina (100.0%, 98.0%, 98.0%), while in Niger state, processors were dominated by women (54.0%). Majority of producers (36.0%), processors (40.0%) in Sokoto state, marketers (36.0%) and processors (53.0%) in Katsina state; and processors (50.0%) in Niger were within the age of 31-40 years. The producer-consumer channel had an efficiency of 618.47 while that for producer-retailerconsumer channel was 435.85. The minimum and maximum average volume (kg) of fish traded within and across the States were for fried (882.25±339.15, 730.72±283.39) and fresh fish (1702.23±978.32; 1673.20±439.88). An average volume (kg) traded of 1386.46±760.57 for dried fish was traded across the regional border. 478.22±292.01 and 91.04±80.53 were the highest and least marketing efficiency among artisanal fishermen and retailers respectively for fresh fish. Processors had the highest average gross margin per kg (₦1157.94±492.26) while wholesalers had the least ₦387.94±363.87 for smoked fish. The Gini coefficient value for most of the actors showed partial inequality in the revenue distribution of fresh, smoked, dried, fried, spiced and frozen fish, except for wholesalers of smoked fish (0.34), retailers of spiced fish (0.45) and iii wholesalers (0.41) and retailers (0.43) of frozen fish. The linear regression b values for all the forms of fish were positive except for dried and fried whose b values were -7.66 and -5.15 respectively. The direct marketing channels were most efficient for fresh and processed fish. The market structures for most of the producers (capture), marketers and processors were monopolistic in nature and there was barrier into entry for fried and dried fish. Therefore there is need for better organization of fish markets.

通过将区域内鱼类贸易更好地纳入民族国家政策议程，可助力改善非洲的粮食与营养安全并减缓贫困。推动区域鱼类贸易发展亟需相关数据支撑，但目前非洲区域边境沿线的鱼类贸易市场结构、交易产品及贸易规模相关信息较为匮乏。因此，本研究针对尼日利亚-尼日尔边境沿线以及卡因吉湖内陆渔业区域，开展了鱼类交易的市场结构、营销主体特征、分销渠道、市场盈利性与效率的调研。

本研究采用多阶段抽样法选取调研对象：在尼日利亚-尼日尔边境沿线，通过随机抽样选取索科托、卡齐纳、吉加瓦和约贝4个州；同时结合区位条件，针对性选取卡因吉湖内陆渔业所在的尼日尔州。研究采用结构化问卷（structured questionnaire）收集数据，每个州调研150名受访者，其中生产者、加工者与营销者各50名，5个州总计750名受访者。收集的信息涵盖社会经济特征、营销运营、渠道结构、盈利性及贸易流向等维度。

数据分析环节，研究采用描述性统计、预算指数、基尼系数（Gini coefficient）、线性回归、随机前沿生产模型（Stochastic production frontier model）及方差分析（ANOVA），并设定显著性水平α=0.05。结果显示：卡齐纳州的生产者、营销者与加工者均以男性为主，占比分别为100.0%、98.0%、98.0%；而尼日尔州的加工者则以女性为主，占比54.0%。年龄结构方面，索科托州多数生产者（36.0%）与加工者（40.0%）、卡齐纳州多数营销者（36.0%）与加工者（53.0%），以及尼日尔州多数加工者（50.0%）的年龄处于31-40岁区间。

营销渠道效率方面，生产者-消费者渠道的效率为618.47，生产者-零售商-消费者渠道的效率为435.85。各州内部及跨州交易的鱼类交易量中，油炸鱼的平均交易量为730.72±283.39千克（最低）至882.25±339.15千克（最高），鲜鱼则为1673.20±439.88千克至1702.23±978.32千克；跨境交易的干鱼平均交易量为1386.46±760.57千克。

在鲜鱼交易的营销效率中，个体渔民的营销效率最高（478.22±292.01），零售商最低（91.04±80.53）。烟熏鱼交易的单位千克毛利润中，加工者的平均毛利润最高，为1157.94±492.26奈拉，批发商最低，为387.94±363.87奈拉。

针对各类鱼类交易的收入分配情况，多数主体的收入分布存在部分不平等，仅烟熏鱼批发商（0.34）、调味鱼零售商（0.45）、冷冻鱼批发商（0.41）与零售商（0.43）除外。线性回归分析显示，除干鱼与炸鱼外，其余品类交易的回归系数b值均为正值，其中干鱼的b值为-7.66，炸鱼为-5.15。直接营销渠道对鲜鱼及加工鱼的效率最高。

研究结果表明，多数生产者、营销者与加工者所处的市场结构为垄断型，且油炸鱼与干鱼交易存在市场进入壁垒。因此，有必要进一步优化鱼类交易市场的组织与管理。