Effect
of stocking weight and stocking density on production of hybrid striped bass
(Sunshine) in earthen ponds in the second phase of a 2-phase
L.R.
D'Abramo,
C.L. Ohs, T.R. Hanson-2004
Journal
of the World Aquaculture Society, 35(1): 33-45
(from ISI Current Contents)
Abstract:
Sunshine bass from Phase I of pond production were graded into two weight
classes, 3 and 5 g, and stocked into experimental earthen ponds at a density
of either 8,649/ha or 11,120/ ha in a 2 X 2 factorial design. After
stocking, the fish were fed a commercially manufactured feed (43.0-45.5%
crude protein) twice daily to satiation for 17 mo. At harvest, mean survival
ranged from 67.4 to 84.8% but was highest for the fish stocked at 5g.
Average production for ponds stocked at 8,649/ha and 11,120/ha, regardless
of stocking weight, was 4,506 kg/ha and 5,550 kg/ha, respectively.
Production and percentages of assigned weight classes were not significantly
different among treatments as a result of wide variation among replicates.
Using size-dependent market prices assigned to the different harvest size
groups, an economic analysis revealed gross receipts, variable costs, and
total costs for the 11,120/ha 5-g treatment. Net returns were not
significantly different among the four treatments due to large variation
among replicates per treatment. These results confirm that the traditional
phase II of pond production can be eliminated in favor of a direct stocking
of phase I fish into a single production phase and economically competes
very well with traditional three-phase growout management. The potential
reduction in turnover time of production units achieved through the direct
stock practice is an efficiency trait that should translate into
significantly higher returns and a greater profit over the long term.
Further reduction of stocking density combined with a stocking weight
greater than 5 g should translate into greater proportion of larger, higher
valued fish at harvest and a growout period of 18-20 mo, rather than the
2430 mo traditionally needed for the combined phase II and phase III of
production.
(Mississippi
State Univ., Dept. Wildlife & Fisheries, Box 9690, Mississippi State MS
39762, USA)