Table 8. The spawning frequency and egg production of Sawthewdon niloticus Ghana females in interspecific spawning
crosses with S. aureus males weighing 50 g each over a 12-month period (Hulata et al. 1980 and Hulata unpublished
data).
Female nc Date of svawninr!
-- --
Total Average No. Average
egg eggs1 of interval
count spawn* spawns (days)Date 614- 715- 2116- 817- 2318- 1419- 9110- 26110-
1 No. eggs 82 41 230 171 298 220 399 1,441 205 8
Interval 31 45 17 46 22 25 17 29
(days)
Date 1016- 817- 1218- 619- 2110-26110-
2No.eggs 274 375 360 467 158 172
Interval 28 35 24 26 24
(days)
Date 1817- 1518- 619- 2110- 22110- 26111-
3 No.eggs 283 55 247 368 272
Interval 27 22 28 20 35
(days)
Date 817- 1518- 619- 2110- 22110- 26111-
4 No. eggs 251 298 451 214 449 383
Interval 38 21 27 20 34
(days)
Date 518- 1719- 6111-
5 No. eggs 254 390 284
Interval 42 49
(days)
Date 2618- 2419-
6 No. eggs 414 200
Interval 26
(days)
Date 1419.
7No.eggs 210
Interval -
(days)
Date
8 No. eggs 0 0 0
Interval
(days)
Date
9 No. eggs 0 0 0
Interval
(days)
*This figure represents only the average amount of eggs in fertile spawns.
**Infertile spawns: eggs not counted.
For interspecific spawning in ponds, it is practically impossible to obtain
any information on the fecundity of individual spawners and only the total
fecundity of the broodstock can be studied. Crosses between 3 groups
of nine S. niloticus Ivory Coast females and three S. hornorurn males (mean
individual weight of both sexes, 45 g) in triplicate experimental ponds
yielded 223, 280, and 404 frylpond for a 72day period (Lovshin and Da
Silva 1975). The same authors reported no significant difference in hybrid
fry production from two spawning groups: S. niloticus Ivory Coast females x
S. hornorurn males (10 99: 5 dd and 6 99: 3 dd). There was a high variability