| Author | Bevis, Randall |
| Call Number | AIT Thesis no. AE-94-29 |
| Subject(s) | Tilapia
Fishes--Spawning
|
| Note | A thesis submitted in partial fulfillment of the requirements for the degree
of Master of Science, School of Environment, Resources & Development |
| Publisher | Asian Institute of Technology |
| Abstract | Artificial nest sites were placed in 20 m2 nylon hapas for a series of
four short tilapia spawning experiments, which were conducted from February
through May 1994 in Udon Thani Province, northeastern Thailand.
The first two experiments were used to determine what size (0 . 25 m
2 or
0.5 m2) and depth (15 or 30 cm) of nests would give the best spawning r esults
for both large and small broodfish. In Experiment 1 large males of 318 g and
females of 180 g were stocked at 100 fish per unit at a 1:1 sex ratio. In
the second experiment small males of 69 g and females of 51 g were stocked
at 120 fish per unit also 1:1 sex ratio.
The small shallow nests (0 . 25 m2 x 15 cm) gave the best performance over
a range of spawning indicators and were selected as the nests to be used for
the third and fourth experiments which both used the small broodstoc k.
The third experiment used densities of 50, 100 or 200 fish (1 :1) and
0, 40 or 80 nests per unit. Total seed production did not significantly
improve with the addition of nest treatments over the 4 seed harvests
(p>0.05). But when analysis was done for fish wi th prior experience to nests
(harvest 1 excluded) artificial nest did produce sign ificantly more seed
(p<0.05). Early viability and clutch sizes (stage 1 eggs) were found to
increase significantly from 0 to 80 nests per unit for broodfish densit i es
of 100 and 200 fish (p<0.05).
The fourth experiment used 200 fish per unit in sex ratios of 1:1, 2:1
or 3:1 with 0 or 80 nests. Total seed production was not significantly
different among sex ratios or nest treatments. Egg viability was
significantly higher for eggs from 80 nest treatments in 1:1 and 2:1 sex
ratios (p<0.05). High temperature and low dissolved oxygen levels were also
seen to negatively effect spawning intensity and early viability during this
experiment. |
| Year | 1994 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Agricultural and Food Engineering (AE) |
| Chairperson(s) | Little, David C.
|
| Examination Committee(s) | Yakupitiyage, Amararatne ;Lin, Chang Kwei
|
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 1994 |
