9 research outputs found
Growth, mortality, exploitation, and recruitment patterns of Labeobarbus altianalis (Boulenger, 1900) in River Kuja-Migori, Kenya
No full textThe Ripon barbel, Labeobarbus altianalis, a riverine fish found in the Lake Victoria Basin is regarded as species of less concern, but it is vulnerable to overfishing and population decline. This study aimed at determining growth, mortality, exploitation rate, and recruitment patterns of L. altianalis (Boulenger, 1900) in River Kuja-Migori. A total of 1,217 specimens with overall total lengths ranging from 9.5-41.5 cm (mean 28.5 ± 2.7) were collected monthly from January to December 2021. The fish were caught using an electrofisher in wadable areas and monofilament nets in deeper areas. Electronic length frequency analysis (ELEFAN) software in Fish Stock Assessment Tools (FiSAT II) program was used to analyze data. Natural mortality (M) Fishing mortality (F) and total mortality (Z) coefficients were 0.15 year-1, 0.52 year-1 and 0.67 year-1 respectively. The asymptotic length (L∞) was 44.94 cm TL while the instantaneous growth rate (K) was 0.15 year-1. The exploitation rate was 0.44 year-1 and the length-based growth performance index (Ø’) was 3.03. Results indicated that the longevity of L. altianalis was 9 years. Recruitment occurs throughout the year with bimodal annual recruitment peaks coinciding with the two rainy seasons in the region. This study provides important information for developing management advice for the L. altianalis riverine fishery.El barbus, Labeobarbus altianalis, un pez ribereño que se encuentra en la cuenca del Lago Victoria, se considera una especie de menor preocupación, pero es vulnerable a la sobrepesca y al declive de la población. Este estudio tuvo como objetivo determinar el crecimiento, la mortalidad, la tasa de explotación y los patrones de reclutamiento de L. altianalis (Boulenger, 1900) en el Río Kuja-Migori. Se recolectó un total de 1.217 especímenes con longitudes totales generales que oscilaron entre 9,5 y 41,5 cm (media 28,5 ± 2,7) mensualmente de enero a diciembre de 2021. Los peces se capturaron utilizando un electropescador en áreas vadeables y redes de monofilamento en áreas más profundas. Se utilizó el software de análisis electrónico de frecuencia de longitud (ELEFAN) en el programa Fish Stock Assessment Tools (FiSAT II) para analizar los datos. Los coeficientes de mortalidad natural (M), mortalidad por pesca (F) y mortalidad total (Z) fueron 0,15 año-1, 0,52 año-1 y 0,67 año-1 respectivamente. La longitud asintótica (L∞) fue 44,94 cm TL mientras que la tasa de crecimiento instantáneo (K) fue 0,15 año-1. La tasa de explotación fue 0,44 año-1 y el índice de desempeño de crecimiento basado en la longitud (Ø’) fue 3,03. Los resultados indicaron que la longevidad de L. altianalis fue de 9 años. El reclutamiento ocurre durante todo el año con picos de reclutamiento anual bimodal que coinciden con las dos estaciones lluviosas en la región. Este estudio proporciona información importante para brindar asesoramiento de gestión para la pesquería fluvial de L. altianalis
Growth, mortality, exploitation, and recruitment patterns of Labeobarbus altianalis (Boulenger, 1900) in River Kuja-Migori, Kenya
No full textThe Ripon barbel, Labeobarbus altianalis, a riverine fish found in the Lake Victoria Basin is regarded as species of less concern, but it is vulnerable to overfishing and population decline. This study aimed at determining growth, mortality, exploitation rate, and recruitment patterns of L. altianalis (Boulenger, 1900) in River Kuja-Migori. A total of 1,217 specimens with overall total lengths ranging from 9.5-41.5 cm (mean 28.5 ± 2.7) were collected monthly from January to December 2021. The fish were caught using an electrofisher in wadable areas and monofilament nets in deeper areas. Electronic length frequency analysis (ELEFAN) software in Fish Stock Assessment Tools (FiSAT II) program was used to analyze data. Natural mortality (M) Fishing mortality (F) and total mortality (Z) coefficients were 0.15 year-1, 0.52 year-1 and 0.67 year-1 respectively. The asymptotic length (L∞) was 44.94 cm TL while the instantaneous growth rate (K) was 0.15 year-1. The exploitation rate was 0.44 year-1 and the length-based growth performance index (Ø’) was 3.03. Results indicated that the longevity of L. altianalis was 9 years. Recruitment occurs throughout the year with bimodal annual recruitment peaks coinciding with the two rainy seasons in the region. This study provides important information for developing management advice for the L. altianalis riverine fishery.El barbus, Labeobarbus altianalis, un pez ribereño que se encuentra en la cuenca del Lago Victoria, se considera una especie de menor preocupación, pero es vulnerable a la sobrepesca y al declive de la población. Este estudio tuvo como objetivo determinar el crecimiento, la mortalidad, la tasa de explotación y los patrones de reclutamiento de L. altianalis (Boulenger, 1900) en el Río Kuja-Migori. Se recolectó un total de 1.217 especímenes con longitudes totales generales que oscilaron entre 9,5 y 41,5 cm (media 28,5 ± 2,7) mensualmente de enero a diciembre de 2021. Los peces se capturaron utilizando un electropescador en áreas vadeables y redes de monofilamento en áreas más profundas. Se utilizó el software de análisis electrónico de frecuencia de longitud (ELEFAN) en el programa Fish Stock Assessment Tools (FiSAT II) para analizar los datos. Los coeficientes de mortalidad natural (M), mortalidad por pesca (F) y mortalidad total (Z) fueron 0,15 año-1, 0,52 año-1 y 0,67 año-1 respectivamente. La longitud asintótica (L∞) fue 44,94 cm TL mientras que la tasa de crecimiento instantáneo (K) fue 0,15 año-1. La tasa de explotación fue 0,44 año-1 y el índice de desempeño de crecimiento basado en la longitud (Ø’) fue 3,03. Los resultados indicaron que la longevidad de L. altianalis fue de 9 años. El reclutamiento ocurre durante todo el año con picos de reclutamiento anual bimodal que coinciden con las dos estaciones lluviosas en la región. Este estudio proporciona información importante para brindar asesoramiento de gestión para la pesquería fluvial de L. altianalis
Patrones de crecimiento, mortalidad, explotación y reclutamiento de Labeobarbus altianalis (Boulenger, 1900) en el Río Kuja-Migori, Kenia
No full textThe Ripon barbel, Labeobarbus altianalis, a riverine fish found in the Lake Victoria Basin is regarded as species of less concern, but it is vulnerable to overfishing and population decline. This study aimed at determining growth, mortality, exploitation rate, and recruitment patterns of L. altianalis (Boulenger, 1900) in River Kuja-Migori. A total of 1,217 specimens with overall total lengths ranging from 9.5-41.5 cm (mean 28.5 ± 2.7) were collected monthly from January to December 2021. The fish were caught using an electrofisher in wadable areas and monofilament nets in deeper areas. Electronic length frequency analysis (ELEFAN) software in Fish Stock Assessment Tools (FiSAT II) program was used to analyze data. Natural mortality (M) Fishing mortality (F) and total mortality (Z) coefficients were 0.15 year-1, 0.52 year-1 and 0.67 year-1 respectively. The asymptotic length (L∞) was 44.94 cm TL while the instantaneous growth rate (K) was 0.15 year-1. The exploitation rate was 0.44 year-1 and the length-based growth performance index (Ø’) was 3.03. Results indicated that the longevity of L. altianalis was 9 years. Recruitment occurs throughout the year with bimodal annual recruitment peaks coinciding with the two rainy seasons in the region. This study provides important information for developing management advice for the L. altianalis riverine fishery.El barbus, Labeobarbus altianalis, un pez ribereño que se encuentra en la cuenca del Lago Victoria, se considera una especie de menor preocupación, pero es vulnerable a la sobrepesca y al declive de la población. Este estudio tuvo como objetivo determinar el crecimiento, la mortalidad, la tasa de explotación y los patrones de reclutamiento de L. altianalis (Boulenger, 1900) en el Río Kuja-Migori. Se recolectó un total de 1.217 especímenes con longitudes totales generales que oscilaron entre 9,5 y 41,5 cm (media 28,5 ± 2,7) mensualmente de enero a diciembre de 2021. Los peces se capturaron utilizando un electropescador en áreas vadeables y redes de monofilamento en áreas más profundas. Se utilizó el software de análisis electrónico de frecuencia de longitud (ELEFAN) en el programa Fish Stock Assessment Tools (FiSAT II) para analizar los datos. Los coeficientes de mortalidad natural (M), mortalidad por pesca (F) y mortalidad total (Z) fueron 0,15 año-1, 0,52 año-1 y 0,67 año-1 respectivamente. La longitud asintótica (L∞) fue 44,94 cm TL mientras que la tasa de crecimiento instantáneo (K) fue 0,15 año-1. La tasa de explotación fue 0,44 año-1 y el índice de desempeño de crecimiento basado en la longitud (Ø’) fue 3,03. Los resultados indicaron que la longevidad de L. altianalis fue de 9 años. El reclutamiento ocurre durante todo el año con picos de reclutamiento anual bimodal que coinciden con las dos estaciones lluviosas en la región. Este estudio proporciona información importante para brindar asesoramiento de gestión para la pesquería fluvial de L. altianalis
Influence of Participation of School Youth in Decision Making During Showcasing Success Stories by Young Agripreneurs on Implementation of Agricultural Programmes
No full textSchool agriculture programme was introduced in secondary education curriculum in Kenya in 1965 and has academic objective to transfer scientific knowledge, and a vocational one to impart skills that would enable youth become self reliant. However, the vocational objective is scantly attained and school youth are inadequate in skills necessary for creation of livelihoods. It is expected that school youth would acquire more and specialized skills for independence through implementation of agricultural programmes such as in showcasing success stories by young agripreneurs. Participation in decision making on the showcasing events would act as motivation for youth to increase implementation of agricultural programmes. However, there is problem of low participation of school youth in decision making on implementation during showcasing success stories by young agripreneurs. This research was conducted to establish the influence of participation of school youth in decision-making during showcasing by young agripreneurs on implementation of agricultural programmes. The study was carried out in extra-county, county and sub-county category of secondary schools offering agriculture subject and, spread in five agro-ecological zones typical of Kenyan farm types, and found in Kisii and Nyamira counties region. Cross-sectional survey design was used. School youth are secondary school form fours taking the subject and implementing KCSE agriculture project. Stratified, purposive, and simple random sampling procedures were used to select a sample of 361 school youth. Data was collected using questionnaires, analyzed by descriptive and inferential statistics at probability level of 0.05 using SPSS version 21. Results show that school youth are well exposed to showcasing success stories by young agripreneurs for acquiring more and specialized implementation skills. It also confirms that gender of youth in school does not make a significant difference in the level of participation in decision making during showcasing events by young agripreneurs. School youth rated five of the six strategies evaluated as very important, and identified some amongst them as more significantly very important than the rest in increasing their participation during showcasing by young agripreneurs. There is a positive significant and linear correlation between level of participation in decision making during showcasing of success stories by young agripreneurs and level of implementation of agricultural programmes by school youth (R= 0.30, p = 0.00), p = 0.00). These findings will be useful in addressing issues of school youth participation in decision making during showcasing by young agripreneurs to motivate others implement agricultural programmes for self reliance
Engagement of Out of School Youth in Decision Making During Showcasing of Success Stories by Young Agripreneurs and Its Effect on Implementation of Agricultural Programmes
No full textParticipation of out of school youth in decision making on showcasing success stories by young agripreneurs would act as motivation for them to increase implementation of agricultural programmes for self reliance. However, there is problem of low participation of out of school youth in decision making on showcasing success by young agripreneurs. Out of school youths who have completed secondary school agriculture are scantly exposed in agripreneurship. It is expected that the gap in knowledge and skills would be filled by the youth participating in showcasing success events by young agripreneurs. This research was conducted to establish the influence of participation of out of school youth in decision-making on showcasing success stories by young agripreneurs on implementation of agricultural programmes. The investigation was conducted in three categories of secondary schools offering agriculture subject, spread in five agro-ecological zones typical of Kenyan farm types, and found in Kisii and Nyamira counties region. Cross-sectional survey design was used. Out of school youth are those who studied agriculture subject and are registered with youth groups within their localities engaged in agricultural activities for creation of livelihoods. Stratified, purposive, and simple random sampling procedures were used to select a sample size of 160 out of school youth. Data was collected using questionnaires, analyzed by descriptive and inferential statistics at probability level of 0.05 using SPSS version 21. Results show that gender of out of school youth does not make a significant difference in the level of participation in decision making on showcasing events by young agripreneurs. Youth out of school are in concurrence that strategies 5, 4, 3 and 6 are more significantly very important than the rest in increasing their participation in decision making during showcasing success stories by young agripreneurs. Strategy 5 is identified as outstanding out of the four and advocates for the formation of agribusiness clubs at community level where successful agripreneurs can mentor the out of school youth, share ideas, experiences and showcase their successes. There is a positive significant linear correlation between level of participation in decision making during showcasing of success stories by young agripreneurs and the level of implementation of agricultural programmes by youth out of school (R= 0.438762, p = 0.00). These findings will be useful in addressing issues of out of school youth on participation in decision making during showcasing success stories by young agripreneurs to prompt them implement agricultural programmes for independence
Saving the endangered Native Victoria Tilapia, Oreochromis variabilis Boulenger (1906), in Upper Victoria Nile
No full text This study investigated the catch estimates, mortality, growth, food and feeding habits, andwater parameters of Oreochromis variabilis in Upper Victoria Nile (UVN) from 2008 to 2019. Catchrates ranged 0.32±0.08 to 3.42±1.13 kg, boat-1, day-1 with the length-weight relationship indicatingIsometric growth. Growth parameters obtained were L∞=36.75, K=0.44 yr-1, t0=-0.4540,tmax=6.4years, ØL=2.774, ØW=-0.301. Total mortality (Z) was 1.74yr-1, natural mortality (M)=0.95yr-1 using riverine surface temperature (RST) of 26oC giving a fishing mortality F of 0.79 yr-1and exploitation ratio (E) of 0.4504 showing that growth parameters concurs with annual estimatesand yield (F=6.589; P±=0.05). Catch estimates correlated with water parameters that indicated asignificant difference. Mortality parameters showed that the fishery could be experiencingexploitation pressure. Although growth rates revealed that the fish is a long-lived species, if managedproperly, its population could recover. Therefore, culturing the species and restocking in rivers andlakes in which this specie was not observed in the East African region are recommended
Stock Assessment of Lates niloticus in Upper Victoria Nile and its Impact on Uganda’s Economy
No full textThis study investigated the growth, mortality, recruitment, and catch estimates of Nile perch, Lates niloticus (Linnaeus, 1758), in Upper Victoria Nile, basing on total catches and length-frequency data collected between 2008 and 2018. The asymptotic length (L∞) had a value of 93.45 cm TL, growth curvature (K) was 0.446 year-1, total mortality (Z) was 1.85year-1, natural mortality (M) was 0.79 year-1, fishing mortality (F) was 1.09 year-1, exploitation rate (E) was 0.59 and growth performance index(ᴓ) of (L∞) was 3.604. There were two peaks recruitment period, a minor one in March and a major one in August. These respectively accounted for 12.8 and 26.3 percent of the total catch. The optimum sustainable yield (E0.5), maximum sustainable yield (Emax) and, economic yield (E0.1) was 0.278, 0.421 and 0.355 respectively. The findings suggest that there is a decline in the population of Lates niloticus in Upper Victoria Nile. Therefore, strict management of the fishery by adhering to the recommended slot size of 50-85 cm TL and curtailing use of illegal gears is needed. This will be possible through enforcement of regulations, monitoring, control and surveillance in order to ensure sustainability of the Nile perch fishery and ecosystem restoration in the Upper VictoriaNile.Keywords: Lates niloticus; Catch rates; Growth parameters, Upper Victoria Nile
Saving the endangered Native Victoria Tilapia, Oreochromis variabilis Boulenger (1906), in Upper Victoria Nile
No full textThis study investigated the catch estimates, mortality, growth, food and feeding habits, and water parameters of Oreochromis variabilis in Upper Victoria Nile (UVN) from 2008 to 2019. Catch rates ranged 0.32±0.08 to 3.42±1.13 kg, boat-1, day-1 with the length-weight relationship indicating Isometric growth. Growth parameters obtained were L∞=36.75, K=0.44 yr-1, t0=-0.4540, tmax=6.4years, ØL=2.774, ØW=-0.301. Total mortality (Z) was 1.74yr-1, natural mortality (M) =0.95yr-1 using riverine surface temperature (RST) of 26oC giving a fishing mortality F of 0.79 yr-1 and exploitation ratio (E) of 0.4504 showing that growth parameters concurs with annual estimates and yield (F=6.589; P±=0.05). Catch estimates correlated with water parameters that indicated a significant difference. Mortality parameters showed that the fishery could be experiencing exploitation pressure. Although growth rates revealed that the fish is a long-lived species, if managed properly, its population could recover. Therefore, culturing the species and restocking in rivers and lakes in which this specie was not observed in the East African region are recommended
Increasing mercury bioaccumulation and biomagnification rates of Nile perch (Lates niloticus L.) in Winam Gulf, Lake Victoria, Kenya
No full textThe Nile perch (Lates niloticus L.) commercial fishery for Lake Victoria in East Africa is an important source of revenue and employment. We focused on shifts in food web structure and total mercury (THg) bioaccumulation and biomagnification in Nile perch, and lower food web items collected from Winam Gulf (Kenya) sampled 24 years apart (1998 and 2022). Stable isotope carbon (δ13C) values were higher in all species from 2022 compared to 1998. Stable nitrogen isotope (δ15N) values in baseline organisms were lower in 2022 compared to 1998. In Nile perch, δ15N values were correlated with total length, but the δ15N-length regressions were steeper in 1998 compared to 2022 except for one large (158 cm) Nile perch from 1998 with an uncharacteristically low δ15N value. Total Hg concentrations were lower in lower trophic species from 2022 compared to 1998. However, the THg bioaccumulation rate (as a function of fish length) in Nile perch was greater in 2022 compared to 1998 resulting in 24.2 % to 42.4 % higher wet weight dorsal THg concentrations in 2022 Nile perch for market slot size (50 to 85 cm) fish. The contrasting observations of increased THg bioaccumulation with size in 2022 against decreases in the rate of trophic increase with size and lower THg concentrations of lower food web items imply reduced fish growth and potential bioenergetic stressors on Winam Gulf Nile perch. All samples except 1 large Nile perch (139 cm total length collected in 2022) had THg concentrations below the European Union trade limit (500 ng/g wet weight). However, for more vulnerable individuals (women, children and frequent fish eaters), we recommend a decrease in maximum monthly meal consumption for 55–75 cm Nile perch from 16 meals per month calculated for 1998 to a limit of 8 meals per month calculated for 2022.</p
