Abstract:

Despite Artemia being the most widely used live feed for successful larval weaning and rearing,
unreliable quality, not being readily available and expensive especially to small fanners hinders
its use. This study explored production of Artemia using waters from saline crater lakes of
western Uganda. Local Artemia production will contribute towards reducing the low survivals in
hatcheries more especially for African catfish (Clarias gariepinus) by providing affordable
Artemia of reliable quality and quantity to the hatchery operators. Limno- biophysical chemistry
was used to identify the best suited lakes for bio-manipulation to produce Artemia. Limno-biophysical
chemical findings indicated the studied lakes ranged between 0.2±0.0m and 2.3±0.3m
(depth), O.OiO.OmgL1 and 205.0il5.3mgL1 for salinity, 27.9iO.3°C and 34.4±2.4°C for
temperature, 18.6i0.1 pscm'1 and 106.3i3.5 pscm'1 for conductivity, 1.7i0.4 mgl’1 and
b.Oil.Omgl'1 for Dissolved Oxygen and 9.6i0.1 and 11.5±1.0 for pH, with no occurrence of
local Artemia resources. Other than Lake Bagusa where Anabaena circinalis was found to
dominate the algal biomass, Spirurina platensis was the dominant algal biomass in majority of
these lakes. Lake Kikorongo had the highest zooplankton diversity, having Brachionus
calyciflorus as the most abundant (50 to 100 individuals /litre). Hatchability experiments using
five commercial Artemia strains: Artemia franciscana from Great Salt Lake (GSL), A.
franciscana from salt ponds in Vinh Chau (VC), Chinese strain (Chinese), TUZ Parthenogetic
Artemia from Kazakhstan (TUZ) and Parthenogenetic Artemia strain from Siberia (PAS) using
waters from crater lakes indicated Artemia franciscana (VC) to have significantly higher
hatching percentage of 93.9±29.4 and 79.8±15.2 for lake Bagusa, 89.3±6.9 and 92.7±3.6 for lake
Katwe, 83.4±10.7 and 83.5±9.1 for lake Maseche in the dry and wet season respectively (P
<0.05). Bucket culture experiments of the best performing commercial Artemia strains from
the hatchability experiments indicated survival and mean total length of GSL Artemia nauplii
cultured at salinities of 40 and 60g/l to be significantly higher than that cultured at salinities of
80 and 100g/l. VC Artemia nauplii cultured at salinity of 40g/l was found to have significantly
higher growth rate (length increment) than those at salinities of 60g/l, 80g/l and 100g/l
(Asymptotic sig (2-sided tested) < 0.000). Pond culture experiments showed that the highest
mean total lengths of GSL and VC Artemia nauplii were 921.0pm and 923.0±91.9pm
respectively when cultured at salinities of 60g/l for lOdays. No Artemia nauplii were found to
survival beyond day 10 of culture at both salinities of 60 and 80g/l. The mean survival of both
GSL and VC Artemia nauplii did not significantly vary across the treatments (60 and 80g/l) after
the same culture period in the salt ponds (Asymptotic sig (2-sided tested) > 0.200). Although
more research is needed to establish the cause for the high mortalities after 8 and lOdays of
culturing in buckets and ponds respectively, this results show that it possible to culture Artemia
using waters from alkaline saline crater once these waters are bio-manipulated to favorable
conditions for Artemia production.