Stock Assessment of Lates niloticus in Upper Victoria Nile and its Impact on Uganda’s Economy

Abstract

Abstract. This 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 lengthfrequency 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 Victoria
Nile.