Lakes and Reservoirs: Research and Management最新文献

{"title":"Balancing ecosystem integrity and cultural values at sacred Lake Hora, Ethiopia: The need for conservation of wetland vegetation","authors":"Mesfin Gebrehiwot,&nbsp;Berhanu Gebrekidan,&nbsp;Melese Asmare,&nbsp;Demeke Kifle,&nbsp;Metadel Adane,&nbsp;Haileyesus Girma,&nbsp;Ludwig Triest,&nbsp;Iris Stiers","doi":"10.1111/lre.12405","DOIUrl":"10.1111/lre.12405","url":null,"abstract":"<p>Although macrophytes represent important habitats for the plankton communities of shallow lakes and ponds, the role of littoral macrophyte patches in deep crater lakes is not well described. The objective of the present study was to investigate the role of littoral macrophyte vegetation in structuring phytoplankton and zooplankton communities and, therefore, sustaining ecological integrity in a deep tropical crater lake (Hora Lake, Ethiopia). The lake has a surface area of 1.03 km² and a mean depth of 16.5 m. The area surrounding the lake is a prime location for the celebration of the Oromo thanksgiving festival (<i>Irreecha</i>), which is inscribed by the United Nations Educational, Scientific and Cultural Organization (UNESCO) as an intangible cultural heritage, and also considered sacred by the Oromo people. Measurements of physical, chemical and biological parameters were conducted at fifteen sampling sites in both the littoral and central parts of the lake during the dry and wet seasons in 2017. A total of 28 phytoplankton and 19 zooplankton genera were identified. The phytoplankton and zooplankton communities were dominated by cyanobacteria and rotifers, respectively, at the open water sites. The wetland vegetation was found to be important in reducing potentially toxic and unsightly cyanobacteria. The submerged and emergent vegetation also served as refugia for zooplankton during the wet and dry seasons, respectively. Crustaceans accounted for about 30–45% of the total zooplankton abundance within the vegetation fringes. Their abundance decreased to 5% in the non-vegetated areas, wherein the community was dominated by rotifers. As the population around the lake, particularly during the festival, may damage the aquatic vegetation, their access to the shoreline should be regulated for conservation and sanitary reasons (e.g. to reduce cyanobacteria growths).</p>","PeriodicalId":39473,"journal":{"name":"Lakes and Reservoirs: Research and Management","volume":"27 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122077484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Physicochemical quality of reservoir sediment in irrigation dams of Northern Ghana","authors":"Felix K. Abagale,&nbsp;Thomas Apusiga Adongo","doi":"10.1111/lre.12404","DOIUrl":"10.1111/lre.12404","url":null,"abstract":"<p>The present study assessed the physicochemical quality of irrigation dam reservoir sediment deposits for possible use in enriching soils in Northern Ghana. The surface area of the 9 study reservoirs was divided into upstream, midstream and downstream sections, with 18 undisturbed sediment samples taken at 0–30 cm depth for determining the soil dry bulk density, and 30 samples collected for analysis of particle size distribution, pH, macronutrients, CEC, EC, ESP and SAR. Reservoir sediments were rich in plant macronutrients (K, Ca and Mg) and organic matter and high in silt and clay content. The dry bulk density ranged from 1.10 ± 0.02 g/cm³ to 1.39 ± 0.08 g/cm³, while the sediment particle sizes were 10.3%–24.8% sand, 43.7%–53.1% silt and 30.6%–37.8% clay. The sediment pH ranged from a moderately acidic level of 5.48–6.64, with high levels of organic carbon (1.37%–2.96%) and organic matter (2.36%–5.10%). The total nitrogen (N) was found to be low (0.14%–0.29%), while the phosphorus (P) ranged from 2.6% to 4.9%, about 10 times higher than the FAO recommended normal average range. Except for the potassium (K) in two of the present study reservoirs, the exchangeable bases concentrations in the sediments were within acceptable levels for crop production. The CEC values were within moderate levels (13.69 to 29.84 cmol/kg), corresponding to a non-expanding, chemically inactive clay, while the salinity and sodicity were absent, with the EC varying between 0.03 and 0.27 dS/m and ESP ranging from 1.8% to 12.9%. Pearson's correlation analyses indicated both positive and negative relationships among the various physicochemical parameters. Based on the present study results, desilted irrigation reservoir sediments, being rich in all plant nutrients, except for N, appear to have great potential to enhance crop production for farmers.</p>","PeriodicalId":39473,"journal":{"name":"Lakes and Reservoirs: Research and Management","volume":"27 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126112966","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Institutional, technical and financial sustainability of rural piped drinking water supply on a freshwater island: Case study of Likoma Island, Malawi","authors":"Rochelle H. Holm,&nbsp;Mavuto Tembo,&nbsp;Victor Kasulo,&nbsp;Medson B. Gavanala,&nbsp;Lettow Chilongo","doi":"10.1111/lre.12403","DOIUrl":"10.1111/lre.12403","url":null,"abstract":"<p>Sustainable Development Goal 6 addresses the protection for both drinking water and lakes, and this is especially important for residents of a freshwater island. This study explores the institutional, technical and economic sustainability of a piped drinking water system operating on Likoma Island in Lake Malawi. Data were collected through household surveys and an analysis of historical records. Proximity and accessibility analyses were also conducted for households (<i>n</i> = 185) and their water sources. The results indicated that within 10 years after implementation of the system, 98% of the respondents had piped drinking water within 250 m of their households. Challenges to system sustainability unique to an island setting include the need for boat transportation, inconsistent electrical power supply and lack of island banking services. Factors contributing to broader system success include fishing households with cash income, limited dependence on communal taps, a strong mainland partner, tourism-supported financial management, high payment rate amongst government institutions, system costs covered by pricing of water for customers and a manager with a high level of decision-making authority. Opportunities to make the system more sustainable include reducing non-revenue water losses, using drones or buying a dedicated boat for transport to the island and improving self-sufficiency on the island to respond to equipment emergencies. Rural drinking water supplies in remote lake island communities must meet unique requirements for sustainable operation, and the institutional, technical and economic sustainability factors of Likoma Island illustrate a successful system likely to sustainably continue its operations into the future.</p>","PeriodicalId":39473,"journal":{"name":"Lakes and Reservoirs: Research and Management","volume":"27 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132691318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"First report of the invasive Ceratium furcoides (dinoflagellate) in Paracambi Reservoir, Rio de Janeiro: Risks to the world's largest domestic water treatment plant","authors":"Raphael Ferreira Corrêa,&nbsp;Rafael Lacerda Macêdo,&nbsp;Kauan Nunes Fonseca,&nbsp;Mariana Guedes Ribeiro Thiago,&nbsp;Viviane Bernardes dos Santos Miranda,&nbsp;Mario Luis Orsi,&nbsp;Samira da Guia Mello Portugal,&nbsp;Christina Wyss Castelo Branco","doi":"10.1111/lre.12400","DOIUrl":"10.1111/lre.12400","url":null,"abstract":"<p><i>Ceratium furcoides</i> (Dinophyta) have gained international attention as invasive aquatic species, especially in South America, due to its fast proliferation into various aquatic systems and the subsequent adverse impacts on water quality and native biota. The present study reports the detection of dense populations of <i>C</i>. <i>furcoides</i> in the Paracambi Small Hydropower Plant (SHP) located in the Guandu River basin. Sampling was conducted at five sites during two sampling events in 2019 and 2020 during different seasons (spring and summer), respectively. We used two different standardized sampling methods, including surface collections (SS) (100-ml) traditionally used for quantitative analysis of inland water phytoplankton, as well as filtration of 20-L sub-surface water (FS) through a zooplankton net. The cell densities were higher in SS (599 individuals/ml) than in FS (0.068 individuals/ml), possibly indicating a patchy distribution of <i>Ceratium</i> in the surface water layers. The total cell length exhibited high values (mean length of 249-μm; mean width of 67-μm), possibly accounting for water treatment impairment, an inability of zooplankton to consume them and/or fish gill clogging. This new observation within an extensively investigated area, and a source of water for nine million people, in the present study advocates for integrated samplings that also consider a search for cysts accumulated in the bottom sediments, as well as more detailed spatial and temporal investigations considering the salient features of <i>C</i>. <i>furcoides</i>’ populations.</p>","PeriodicalId":39473,"journal":{"name":"Lakes and Reservoirs: Research and Management","volume":"27 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134577490","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Linking citizen science with contamination levels of small water bodies for generation of essential information for conservation and investment","authors":"Christopher Mulanda Aura,&nbsp;Chrisphine S. Nyamweya,&nbsp;Horace Owiti,&nbsp;Ruth Lewo Mwarabu,&nbsp;Collins Onyango Ongore,&nbsp;Safina Musa,&nbsp;James M. Njiru,&nbsp;Richard Oginga Abila","doi":"10.1111/lre.12402","DOIUrl":"10.1111/lre.12402","url":null,"abstract":"<p>Socio-ecological characteristics of small water bodies (SWBs) are useful in determining the required level of rehabilitation and rebranding for possible blue economic investments. The current study assessed the socio-ecological aspects of 74 SWBs in central and western counties in Kenya to determine their contamination status. The SWBs were selected to account for sub-county representation, coverage and permanence of the water source. Respondents assessed in the selected SWBs catchments were identified from riparian communities and policymakers. Physicochemical parameters were assessed using standard methods. Regionally, the SWBs showed significant variations (<i>p</i> &lt; .05) in the main occupation, ownership, restricted access and perceived alternating extreme precipitation ranges. Significant differences in the selected citizen science attributes and SWBs’ dimensions of both depth and size, were linked to higher total and faecal coliforms in western as compared to central Kenya and higher water transparency in the latter. Thus, localized human activities that had significant variations between the two regions are highly likely to have affected the differences in the contamination levels. The socio-ecological indexing herein can be of general use for determining the contamination status of SWBs as an integrative management tool for possible investment.</p>","PeriodicalId":39473,"journal":{"name":"Lakes and Reservoirs: Research and Management","volume":"27 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116949722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Water quality and ecology of Lake Kanyaboli, Kenya: Current status and historical changes","authors":"Benjamin N. Kondowe,&nbsp;Frank O. Masese,&nbsp;Philip O. Raburu,&nbsp;Wales Singini,&nbsp;Riziki Jacques Walumona","doi":"10.1111/lre.12401","DOIUrl":"10.1111/lre.12401","url":null,"abstract":"<p>Small waterbodies are the most threatened freshwater habitats because of the large ratio between their size and the catchment they drain. The present study assessed the current and historical changes in the physical, chemical and biological variables of Lake Kanyaboli, a satellite lake on the northern shores of Lake Victoria in western Kenya. Primary and secondary data on pH, electrical conductivity (EC), dissolved oxygen (DO) concentration, temperature, Secchi depth (SD), and nitrate (<math>\u0000 <msubsup>\u0000 <mtext>NO</mtext>\u0000 <mn>3</mn>\u0000 <mo>-</mo>\u0000 </msubsup></math>), nitrite (<math>\u0000 <msubsup>\u0000 <mtext>NO</mtext>\u0000 <mn>2</mn>\u0000 <mo>-</mo>\u0000 </msubsup></math>), ammonium (<math>\u0000 <msubsup>\u0000 <mtext>NH</mtext>\u0000 <mn>4</mn>\u0000 <mo>+</mo>\u0000 </msubsup></math>), soluble reactive phosphorus (SRP), total nitrogen (TN), and total phosphorus (TP) and chlorophyll-<i>a</i> (Chl-<i>a</i>) concentrations were utilized in the present study. The results indicated Secchi depth and chlorophyll-<i>a</i> were the most erratic of all the analyzed environmental variables studied, exhibiting a range of 0.69 ± 0.29–0.87 ± 0.34 m and 9.03 ± 0.81–34.97 ± 3.36 µg/L respectively. Two-way ANOVA yielded no significant interactions between sampling sites and seasons for all the variables. Except chlorophyll-<i>a</i>, there also were no significant differences among the sampling sites for the studied variables. Seasonality yielded significant differences for Secchi depth, dissolved oxygen and chlorophyll-<i>a</i>. The Carlson Trophic Index for Chl-<i>a</i> and SD indicated Lake Kanyaboli is currently eutrophic, while the TP concentration indicated hypereutrophic conditions. The lake, however, has fluctuated between eutrophic and hypereutrophic conditions over the past years. Although historical water quality data for the lake is scanty and infrequent, most physical and chemical variables reflected anthropogenic effects on a temporal scale. Interestingly, despite its eutrophic status, the general lake condition is still relatively good, attributable to the buffering effect from the extensive macrophytes fringing it. The present study identified nutrient loading, wetland reclamation and connectivity with the Yala River through a feeder canal as the management issues of critical concern. Accordingly continuous monitoring of the lake's water quality to detect anthropogenic effects is recommended for management intervention purposes.</p>","PeriodicalId":39473,"journal":{"name":"Lakes and Reservoirs: Research and Management","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/lre.12401","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129522849","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysing transboundary water governance: A global-regional-national water governance framework of Tonle Sap Lake","authors":"Mak Sithirith","doi":"10.1111/lre.12396","DOIUrl":"10.1111/lre.12396","url":null,"abstract":"<p>Transboundary water governance is multiscale and multilevel, involving different actors with diverse powers and politics at different levels and scales. Levels and scales are key governance challenges in transboundary water governance. Although there is considerable literature on scale and level, there is very little on how to operationalize it in a transboundary river basin context. Accordingly, the present study analyses how scale and level complicate transboundary water governance, using a literature review and a case study of Tonle Sap Lake (TSL) in the Mekong River Basin to examine the level and scale affecting transboundary water governance. The present study describes the level of transboundary water governance in terms of global, regional and national implications. There are different functional spaces at each level, including agriculture, fisheries and biodiversity. Spaces are zoned into different spatial scales, based on technocratic interests, specialization, power and the politics of actors. The present study concludes that levels, spatial scales and zoning have made TSL governance more complex, leading to establishment of new institutional and legal arrangements for managing Tonle Sap, some of which compete with, conflict and overlap, meaning sound environmental management and good governance cannot be guaranteed.</p>","PeriodicalId":39473,"journal":{"name":"Lakes and Reservoirs: Research and Management","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/lre.12396","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129609618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Shifts in composition of fish species of fishery in Lake Naivasha, Kenya: Trend implications for fishing effort, yields and revenue","authors":"George N. Morara,&nbsp;Albert M. Getabu,&nbsp;James M. Njiru,&nbsp;Reuben Omondi,&nbsp;Alice Mutie,&nbsp;Chrisphine S. Nyamweya","doi":"10.1111/lre.12397","DOIUrl":"10.1111/lre.12397","url":null,"abstract":"<p>Assessing fisheries resource composition and exploitation trends is vital for the sustainable management of fish stocks. Accordingly, the present study analysed datasets of fish catches and market values from 1991 to 2019, and from 2004 to 2019, respectively, to determine shifts and trends in fish species composition, fishing effort, fish yield and revenue. The annual percentage weight composition and relative biomass of different fish species in the lake were calculated over the study period. Fishery time series data comprised fishing effort, fish yield, catch per unit effort (CPUE), revenue and revenue per unit effort (RPUE). Moving average (MA) trends at 5-year intervals were plotted and the Mann–Kendall (MK) method applied to detect trends at the 95% confidence limit. The results identified shifts in fish species composition during various periods, with Nile tilapia <i>Oreochromis niloticus</i> comprising 94% of the total weight of fish landed in 2019, with an overall mean relative biomass of 4221.4 ± 2229.7 kg/km². The mean total fish catch (1683.5 ± 420 ton/year), CPUE (10.6 ± 2.0 ton/boat/year) and modal effort (176 boats) were highest from 2014 to 2019 period. The fishery revenue increased in 2019 (US$ 4,096,490) with a RPUE of US$ 22,263.5/boat/year. The fishing effort, fish yields, CPUE, revenue and RPUE trends increased significantly (<i>p</i> &lt; .01), likely being related to the shifts in species composition. Lake Naivasha is a learning model for improving fisheries management and yields through stock enhancement interventions. Nevertheless, the increasing level of fishing effort warrants a precautionary approach to ensure sustainability of the fishery resource.</p>","PeriodicalId":39473,"journal":{"name":"Lakes and Reservoirs: Research and Management","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/lre.12397","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131236616","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Aligning small indigenous fish species (SIS) in policy and management for enhanced food security and nutrition: The case of the Kenyan Lake Victoria Omena fishery","authors":"Christopher Mulanda Aura,&nbsp;Horace Owiti,&nbsp;Chrisphine Nyamweya,&nbsp;Cyprian O. Odoli,&nbsp;Julia Akinyi Obuya,&nbsp;Zachary Ogari,&nbsp;James M. Njiru,&nbsp;Martin Van der Knaap","doi":"10.1111/lre.12399","DOIUrl":"10.1111/lre.12399","url":null,"abstract":"<p>Fisheries governance uses policy and statutory documents to improve governance on fish ecology, harvesting, trade and consumption by identifying and addressing gaps regarding inefficiencies, inequity and post-harvest losses. The current study examines existing policies and institutional documents on fisheries, health and trade to assess the level of inclusion of small indigenous fish species (SIS), especially Omena, as a means of guiding governance interventions for sustained livelihoods of fishing communities in Lake Victoria. A content-analysis review was conducted on all the fisheries and nutritional policy documents related to Lake Victoria fishery to ascertain the need for their integration into fisheries governance. From the scoring scale, where zero (0) implies no integration and three (3) implies high integration, the study results indicated very low levels of integration across health, fisheries and trade relating to small fish species. Further, the management plans and regulations/guidelines exhibited a relatively higher level of integration than did policies and laws. There is need for a more targeted approach for streamlining the existing policy documents to realize the untapped potential contribution of SIS towards food and nutritional security.</p>","PeriodicalId":39473,"journal":{"name":"Lakes and Reservoirs: Research and Management","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/lre.12399","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115411257","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Aspects of the biology and population structure of Oreochromis niloticus, Coptodon zillii and Oreochromis leucostictus tilapia in Lake Naivasha, Kenya","authors":"Edwine Yongo,&nbsp;Simon W. Agembe,&nbsp;Julius O. Manyala,&nbsp;Edna Waithaka","doi":"10.1111/lre.12398","DOIUrl":"10.1111/lre.12398","url":null,"abstract":"<p>The Nile tilapia (<i>Oreochromis niloticus</i>), Redbelly tilapia (<i>Coptodon zillii</i>) and Blue spotted tilapia (<i>Oreochromis leucostictus</i>) were introduced into Lake Naivasha in the 1950s to diversify and boost the lake fisheries. These species have since been exploited in the commercial gillnet fishery. The fish stocks, however, are currently facing problems of pollution, wetland degradation and intense fishing pressures. Accordingly, the present study investigated some aspects of the biology and population structure of the three tilapiine species in light of changing lake conditions. Fish samples were collected from January to December 2019 using multifilament gillnets of 2.0-to-6.0-inch mesh sizes. Immediately after their capture, the fish specimens were transported to the lab for morphometric measurements and analysis of maturity. The highest and lowest mean (±SD) total length (TL) were exhibited by <i>O</i>. <i>niloticus</i> (22.9 ± 5.2 cm) and <i>C</i>. <i>zillii</i> (14.5 ± 2.1 cm), respectively. Similarly, <i>O</i>. <i>niloticus</i> exhibited a higher mean weight (268.4 ± 18.0 g) and body depth (7.6 ± 2.5 cm), compared to the other species. <i>O</i>. <i>niloticus</i> exhibited an isometric growth pattern, while <i>C</i>. <i>zillii</i> and <i>O</i>. <i>leucostictus</i> exhibited negative allometric growth. The fish species were in good condition, with mean condition factors of 1.59 ± 0.07, 1.51 ± 0.06 and 1.23 ± 0.03 for <i>C</i>. <i>zillii</i>, <i>O</i>. <i>leucostictus</i> and <i>O</i>. <i>niloticus</i>, respectively. Furthermore, the condition factors for <i>O</i>. <i>leucostictus</i> and <i>O</i>. <i>niloticus</i> varied by size class, exhibiting a decreasing trend with increased fish size. The male:female sex ratio revealed significantly more males than females for <i>O</i>. <i>niloticus</i> (2.30:1.0) and <i>O</i>. <i>leucostictus</i> (2.36:1.0), although not for <i>C</i>. <i>zillii</i> (1.15:1.0). <i>O</i>. <i>niloticus</i> (28.0–29.0 cm TL) matured at a larger size, followed by <i>O</i>. <i>leucostictus</i> (21.0–26.0 cm TL), and <i>C</i>. <i>zillii</i> (15.0–17.0 cm TL). In comparison, values of length-weight parameters, condition factor, sex ratio and size at first maturity of the studied fishes varied in Lake Naivasha, Victoria, Albert and George. The gillnet mesh ≤3.0″ mainly targeted small-sized immature fish, while mesh ≥4″ targeted mature fish, particularly <i>O</i>. <i>niloticus</i>. It was concluded that gillnets with ≥4.0″ mesh could safely be applied for this fishery in Lake Naivasha, whereas the use of smaller mesh should be controlled to protect the juveniles as a means of maintaining sustainable fisheries. Furthermore, the present study also provided useful information, including size at maturity that is vital for setting mesh size for managing the lake fishery.</p>","PeriodicalId":39473,"journal":{"name":"Lakes and Reservoirs: Research and Management","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/lre.12398","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125861542","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}