Comparative assessment of diet and condition factor of Cyprinus carpio and Oreochromis leucostictus in Lake Naivasha, Kenya

The study compared and assessed the diet and condition factors of two fish species, Oreochromis leucostictus and Cyprinus carpio, in Lake Naivasha. Fish samples were collected monthly using gill nets (35-70 mm mesh size) from July to December 2013. Stomach contents of all the specimens were analysed using the point method. Results indicated that detritus was the most abundant food item in the diet of both O. leucostictus and C. carpio accounting for 50% and 63%, respectively, while benthic macroinvertebrates contributed the least with each fish having 2%. Rooting and digging behaviour of the carp probably led to both C. carpio and O. leucostictus ingesting the suspended detritus as their main source of food with C. carpio outcompeting O. leucostictus due to its prolific nature and better adaptability to benthic conditions. Fulton’s condition factor of all the fish samples had values of >1. A comparison of the two fish species showed C. carpio had a condition factor of 1.51 while O. leucostictus had 1.32. The higher condition factor of C. carpio in Lake Naivasha is an indication that the fish have better tissue energy reserves, greater reproductive potential and higher survival rates compared to O. leucostictus with a lower condition factor

Seasonal changes in length-weight relationship and condition factor of Nile tilapia, Oreochromis niloticus (Linnaeus, 1758) (Cichlidae) in Lake Naivasha, Kenya

The study compared the length-weight relationship and condition factor (K) of Nile tilapia (Oreochromis niloticus) in Lake Naivasha, Kenya, between the wet and dry seasons. Fish samples were collected monthly by gill netting from February to December 2015. A total of 372 samples of O. niloticus were analysed. The b values in the length-weight relationships were observed as 3.077 and 3.366 in the wet and dry seasons, respectively. The values of b exhibited positive allometric growth which were the important indication that the species was growing faster in weight than length. The K values of the fish ranged 1.18-4.1 during the wet season and 0.8-3.0 during the dry season.  All mean monthly K values were found to be greater than 1, the highest being in June (2.33±0.05) and lowest in February (1.31±0.28), an indication of a healthy status and general well-being of the O. niloticus population in Lake Naivasha. The study concluded that seasonal variation has no great influence in the length-weight relationship and condition factor of O. niloticus in Lake Naivasha

Restocking of small water bodies for a post Covid recovery and growth of fisheries and aquaculture production:socioeconomic implications

Funding: The International Fund for Agricultural Development (IFAD) and The Government of Kenya through the Aquaculture Business Development Programme (ABDP) funded the restocking and data collection and processing.Restocking of fish in Small Water Bodies (SWBs) is one of the technologies that can be used to enhance fish-food production for post Covid recovery and growth in food security, and national development. The current study aimed at assessing the socioeconomic impact and stock performance of restocked Nile tilapia fingerlings in SWBs in 15 counties in the Western and Central regions where the Aquaculture Business Development Programme (ABDP) is implemented. The study employed both primary and secondary data from socioeconomics, environmental characteristics and fisheries and aquaculture aspects. There was no restocked dam with a low (< 1.66) socioeconomic impact, indicating the potential for restocking. The majority (n = 27; 79%) of the restocked SWBs had a moderate (1.66 – 2.33) impact, owing to the inherent constraints of adoptability by the local community. Twenty one percent (n = 7; 21%) of the SWBs had a high (2.34 - 3.00) impact and with better environmental conditions. The average condition factor (K) of tilapia in restocked SWBs was 1.24 ± 0.53 SD, suggesting excellent fish growth condition. Notably, restocking the SWBs could benefit riparian fishing communities by improving their livelihoods and providing food and nutritional security. Given the limited exploitation of fish in most SWBs in the developing countries, additional community awareness and capacity building interventions are needed to enhance optimal use of SWBs in post Covid era.Publisher PDFPeer reviewe

Need for harmonized long-term multi-lake monitoring of African Great Lakes

To ensure the long-term sustainable use of African Great Lakes (AGL), and to better understand the functioning of these ecosystems, authorities, managers and scientists need regularly collected scientific data and information of key environmental indicators over multi-years to make informed decisions. Monitoring is regularly conducted at some sites across AGL; while at others sites, it is rare or conducted irregularly in response to sporadic funding or short-term projects/studies. Managers and scientists working on the AGL thus often lack critical long-term data to evaluate and gauge ongoing changes. Hence, we propose a multi-lake approach to harmonize data collection modalities for better understanding of regional and global environmental impacts on AGL. Climate variability has had strong impacts on all AGL in the recent past. Although these lakes have specific characteristics, their limnological cycles show many similarities. Because different anthropogenic pressures take place at the different AGL, harmonized multi-lake monitoring will provide comparable data to address the main drivers of concern (climate versus regional anthropogenic impact). To realize harmonized long-term multi-lake monitoring, the approach will need: (1) support of a wide community of researchers and managers; (2) political goodwill towards a common goal for such monitoring; and (3) sufficient capacity (e.g., institutional, financial, human and logistic resources) for its implementation. This paper presents an assessment of the state of monitoring the AGL and possible approaches to realize a long-term, multi-lake harmonized monitoring strategy. Key parameters are proposed. The support of national and regional authorities is necessary as each AGL crosses international boundaries

Need for harmonized long-term multi-lake monitoring of African Great Lakes

To ensure the long-term sustainable use of African Great Lakes (AGL), and to better understand the functioning of these ecosystems, authorities, managers and scientists need regularly collected scientific data and information of key environmental indicators over multi-years to make informed decisions. Monitoring is regularly conducted at some sites across AGL; while at others sites, it is rare or conducted irregularly in response to sporadic funding or short-term projects/studies. Managers and scientists working on the AGL thus often lack critical long-term data to evaluate and gauge ongoing changes. Hence, we propose a multi-lake approach to harmonize data collection modalities for better understanding of regional and global environmental impacts on AGL. Climate variability has had strong impacts on all AGL in the recent past. Although these lakes have specific characteristics, their limnological cycles show many similarities. Because different anthropogenic pressures take place at the different AGL, harmonized multi-lake monitoring will provide comparable data to address the main drivers of concern (climate versus regional anthropogenic impact). To realize harmonized long-term multi-lake monitoring, the approach will need: (1) support of a wide community of researchers and managers; (2) political goodwill towards a common goal for such monitoring; and (3) sufficient capacity (e.g., institutional, financial, human and logistic resources) for its implementation. This paper presents an assessment of the state of monitoring the AGL and possible approaches to realize a long-term, multi-lake harmonized monitoring strategy. Key parameters are proposed. The support of national and regional authorities is necessary as each AGL crosses international boundaries