Albert M. Getabu's research while affiliated with Kisii University and other places

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 Oreochromis niloticus 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 (p < .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.

Illegal, unregulated and unreported (IUU) fishing is a negative social vice that adversely affects global capture fishery production. The inadequate disclosure of IUU methods and trends in fishery waters hampers management actions to curb illegal fishing activities. Seldom have empirical studies been conducted on IUU methods and their trends in Lake Naivasha. Therefore, this study analysed data on the fisheries monitoring, control and surveillance (MCS) during 2012 to 2018 to test for the significance of trends, and compare the enforcement plans to seizures of illegal fishing gear in the lake. The IUU fishing methods included both the types of equipment and the means used to perpetrate illicit capture or acquisition of fish from the lake. The results indicate a 37% reduction of MCS enforcement patrols during 2018 compared to 2012, and a 16% to 100% upsurge in the quantity of seized IUU fishing items. Illegal fishing boats potentially threaten the fishery of Lake Naivasha with an additional fishing effort of 22% above the 176 licensed boats. An average of 10,700 fishing nets seized per year has the potential fishing intensity of 74 gillnets/km2 against an ideal intensity of 12 gillnets/km2. The frequencies of MCS patrols in Lake Naivasha exhibit no particular trends and likely ineffective in deterring the upsurge of IUU activities, or the evolution of new illegal fishing methods. An increased seizure of illegal fishing boats, outboard engines and gillnets could imply their rampant use in IUU fishing activities. These findings merit a multi‐stakeholder participatory approach to identifying the MCS weaknesses and opportunities for sharing resources to strengthen the fishery management efforts in Lake Naivasha.