ISSN:
1573-5117
Keywords:
Spawning
;
breeding
;
fecundity
;
Tilapia
;
White Nile
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Two annual breeding seasons are indicated for populations of T. nilotica in the White Nile: a major autumnal season (mid-July–September) coinciding with the annual rainfall and a smaller back-up season in February–March. During these seasons reproducing females constituted 80% and 40% of the total population of mature females compared to 10–12% in the intervening summer period. Enhanced gonadal development, fecundity and GSI values characterized the breeding seasons. Gonadal maturation proceeded uninterruptedly even during the summer and repeated fractional spawning is suggested for this species within and beyond the breeding seasons. Most of the ‘spring’ breeders were either very young or relatively old fish and most medium-sized females bred in the main autumnal season. Older fish were less fecund (by 70–75%) compared to younger fish. In the latter, fecundity increased progressively with body growth (r2 = 0.732; p〈0.001); the proportionality was lost in medium-sized fish and in older females (0.9–1.5 kg) fecundity correlated negatively with increased body size.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00006460
Permalink