Nigerian Journal of Fisheries and Aquaculture

Perceived Effects of Climate Change and Adaptation Strategies Among Fishermen Around Komadugu-Yobe River, Yobe State, Nigeria

Owoade E.O. — 2025-09-29

The study explored the artisanal fishermen perceived effect of climate change and adaptation strategies around the Komadugu-Yobe River, Yobe State, Nigeria. A multi-stage sampling procedure was used to select 120 respondents. Data were elicited with 120 structured questionnaires. The data were subjected to descriptive statistics, Chi-square and Pearson Product-Moment Correlation analysis. The results showed that the fishermen’s mean age was 35.93, 100% were males, and 64.1% were educated and highly experienced in fishing. Fishermen were aware of climate change. Fishermen perceived that climate change affected fisheries resources and livelihood outcomes (The fishermen’s adaptation strategies included increasing the price of captured fish (90.0%), increasing fishing duration (77.5%) and involvement in non-fishing activities (70.8%). There was a significant positive relationship between years of education (r = 0.241, p < 0.05), awareness of climate change (r = 0.328, p<0.05), adoption of adaptation strategies (r = 0.343, p<0.05) and perceived effect of climate change on fisheries resources. In conclusion, fishermen perceived that climate change affected artisanal fisheries of the Komadugu-Yobe River, leading to the adoption of different adaptation strategies. It was recommended that the stakeholders should empower the artisanal fishermen in non-fishing activities, such as fish farming and fish processing activities.

Growth Response of Nile Tilapia (Oreochromis niloticus) Fingerlings Fed Roselle (Hibiscus sabdariffa) Seed Meal Replacing Fish Meal

Yunusa A. — 2025-09-30

This study investigated the efficacy of replacing fish meal with suitable Hibiscus sabdariffa seed meal in the diet of Nile tilapia, Oreochromis niloticus. The aim of study is to evaluate the effects of replacing fish meal with Hibiscus sabdariffa in the diet of Nile tilapia fingerlings. A total of 300 Nile tilapia fingerlings (mean weight 5g) were randomly distributed into five treatments, each with three replicates. The treatments consisted of five iso-nitrogenous dietary formulations: 0 (control), 25, 50, 75 and 100 % replacement of fish meal with roselle seed meal. The results showed that fish fed with 50% roselle seed meal replacing fish meal had significantly (p<0.05) higher weight gain (674.74g), specific growth rate (0.39) and lowest feed conversion ratio (1.02) compared with the control group. Proximate analysis revealed that roselle seed meal contained 32.45% crude protein, 10.25% crude fat, and 5.5% crude fiber. This concludes that replacing up to 50% of fish meal with roselle seed meal in the diet of Nile tilapia fingerlings can improve their growth performance. This finding suggests that roselle seed meal is a viable alternative protein source in sustainable aquaculture practices.

Pollution Status of River Niger Around Ajaokuta Steel Company, Kogi State, Nigeria

Ogungbile P.O. — 2025-09-29

Water samples from the River Niger near the Ajaokuta Steel Company were evaluated for physical and chemical characteristics from six selected sites in wet and dry seasons. Physico-chemical parameters such as temperature, pH, total dissolved solids, biological oxygen, electrical conductivity, total alkalinity, total hardness, chemical oxygen demand, magnesium, calcium, sulphate, manganese, chloride, total iron, and nitrate were determined utilising standard techniques. The comprehensive pollution indices, water quality indices, single factor pollution indices, and contamination indices were utilised to assess the degrees of river pollution in the study site. A flame atomic absorption spectrophotometer was used to assay the samples for their heavy metal content. Quality control procedures included blank determination, recovery analysis, and calibration of standards. Descriptive and inferential statistics were employed for data interpretation. The results revealed that all the physicochemical parameters were below the recommended allowable limit for drinking water, except Fe. Most of the physicochemical parameters were higher in the dry season, except hardness, magnesium, Clorine, and iron. The water quality index was classified as 'good' and 'poor' for the dry season (85.72) and the wet season (108.56), respectively. Comprehensive pollution indices indicated slight and moderate pollution in dry (0.82) and wet (1.09) seasons, respectively, while contamination index classified the water as highly contaminated in both dry (97.67) and wet (203.34) seasons. The overall water quality indices were classified as polluted. Therefore, ensuring the safety of the river source is crucial to safeguard public health and aquatic biodiversity.

Age Structure of Bagrus bayad (Forskal, 1775) and Synodontis schall (Bloch and Schneider, 1801) in River Galma Zaria, Nigeria

Wase D.G. — 2025-09-29

The study investigated the age structures of Bagrus bayad and Synodontis schall from River Galma, Kaduna, Nigeria, to obtain baseline information for sustainable Management of the fisheries resource of the river. Seventy-two (72) female Bagrus bayad (16.45±1.07g-55.23±8.21g weight and 09.65±0.53cm-13.40±0.52cm length) and eighty-seven (87) male B. bayad (11.21±2.08g-38.05±6.09g weight and 08.30±0.34cm-12.09±0.43cm length), making a total of 159 fish. While 72 females of Synodontis schall (7.09±2.11- 49.40±3.60g weight and 6.54±1.32-12.33±0.29cm length) as well as 91 males of S. schall (18.43±3.01-45.80±4.00g weight and 7.21±14-11.98±0.30cm length making a total of 164 fish, were collected from River Galma over 6 months. Otoliths were harvested from the fish by making a transverse cut from the top of the head through the pre-opercula using sharp blades, and the Sagitta was obtained. Otoliths were cleaned of the macula, otolithic membrane, and vestibule. The otoliths were preserved in ethanol and further cleared in 100% glycerine for 7 days. The cleaned otoliths were mounted on glass slides, and annuli rings were read whole using a binocular microscope. The relationship between standard length and age was determined. The result of the otoliths' microstructural examination revealed 0-3+ year groups for B. bayad and 0-2+ year groups for S. schall. There was a positive correlation between age and fish standard length. Bagrus bayad and S. schall in the river Galma are below the maximum life span of nine and six years reported for these species. Thus, they require regulation of catch sizes to ensure maximum sustainable yield.

Morphometric Characterization of African Bony Tongue, Heterotis niloticus (Cuvier, 1829) From Northern Nigeria

Aliyu M. — 2025-09-29

Morphometric characteristics of Heterotis niloticus populations from three waters in Northern Nigeria were investigated to assess their phenotypic variations. One hundred and five (105) fish samples with lengths of 14.5-43.9cm and weights of 120-780g were collected from Alau Dam, Borno State, Tiga Dam, Kano State, and Shiroro Dam, Niger State, Nigeria, and twenty-two morphological characters were measured. The data obtained were subjected to principal components, discriminant functions, and cluster analyses using PAST 4.04. Principal components analysis of morphometric traits extracted ten factors with eigenvalues greater than one. The results show that the first, second, and third PCs accounted for 63.58%, 22.01, and 7.08% variation, respectively. The cumulative percentage rate of the 1^st two PC was 85.87%. Both discriminant factor and clustering analysis in morphometric characters among the Alau, Tiga, and Shiroro H. niloticus resulted in two main clusters. Distances between morphometric variables among H. niloticus populations were 97.30%. The present study revealed morphometric diversity between the H. niloticus strains of Tiga, Shiroro, and Alau Dams. This study provides basic information on morphometric variation in H. niloticus populations from the three Dams, and it could be adopted in fisheries management for conservation and sustainable exploitation of H. niloticus.

Karyotype of the West African Spotted Babywhale Mormyrid Fish, Pollimyrus adspersus in the Oluwa River, Ondo State, Nigeria

Jegede O. I. — 2025-09-20

Pollimyrus is a non-monophyletic and paraphyletic species-rich Mormyridae genus that is still cytogenetically understudied. Here, the chromosome composition of Pollimyrus adspersus in the Oluwa River, Nigeria, was investigated for the first time to determine its karyotype and highlight the cytogenetic relationship between it and the two earlier studied species in the genus. Mitotic cells were arrested at the metaphase stage after a 0.05% peritoneal colchicine injection at 0.05ml per 10g of fish weight for 1 hour. Metaphase chromosomes were extracted from the fish kidney following the standard procedure. Slide staining was done using 6% Giemsa solution. Chromosome metaphases were snapped and processed in Photoshop. Chromosomes were characterised as metacentric, submetacentric, and acrocentric based on centromeric position. Chromosome homologs were paired and arranged in descending order of size. The chromosome number of 2n = 50 all acrocentric; 2n = 50 (50a), recovered from the fish, represents one of the least rearranged Mormyridae chromosome conditions, and was significantly different from its Ethiopian cogenerics; P. nigricans and P. isidori. The present study provides cytogenetic Evidence supporting an earlier morphologically based study that separated the studied species and its Ethiopian counterparts into different clades. Given previous cytogenetic and morphological data and the result presented herein, the appropriateness of retaining the species in the Pollimyrus genus should be reviewed. However, further studies incorporating molecular genetics, electrical organ discharge, and cytogenetics are essential for a more robust approach to the genus taxonomy.