Influence of Artisanal fishing Gears on Physico-Chemical Parameters of Ferguson’s Gulf in Lake Turkana, Kenya

Abstract

The influence of gill net, purse seine and beach seine gears was assessed on the basis of water physicochemical parameters. The study considered a total of seven water quality parameters viz. Dissolved oxygen (DO), salinity, conductivity, Total Dissolved Solids (TDS), pH, Secchi depth and water temperature. Longitudinal study design was used representing dry and wet seasons. The sampling sites were selected on the basis of their relevance as exclusive gill net, purse seine and beach seine fishing sites and control where no fishing activity was taking place. Physicochemical parameters were determined in situ. The data generated was analyzed using one-way ANOVA at p<0.05 and Student’s t-Test at p<0.05 to establish spatial and seasonal mean variation of physico-chemical parameters respectively. Correlational analysis was done to establish the relationship among physico-chemical parameters (p<0.05). Results indicated that temperature, DO, salinity, conductivity, TDS, pH, and Secchi depth were significantly different in sites where gill net, purse seine and beach seine gears were used including control sites (ANOVA, p<0.05). Salinity, conductivity, TDS, pH and Secchi depth varied seasonally (Student’s t-Test, p<0.05) but not dissolved oxygen and temperature. Correlational analysis showed significant correlation of salinity to Total Dissolved Solids (p<0.01, r=0.830) and conductivity (p<0.01, r=0.927). This study revealed that salinity and conductivity values decreased spatially and seasonally towards the mouth of Ferguson’s gulf. The use of purse seine gears led to increased dissolved osygen while gill net sites had high Total dissolved solids. The study recommends monitoring of water quality parameters for fish survival and ecosystem health.