G.B. Ramos*, R. Corcino, H. Rivera, N. Alfonso, G. Sia Su and R. Arcilla
This study primarily aimed to generate basic data that is essential for the management and conservation efforts for the two economically-important fish species of Lake Lanao, Philippines. Specifically, it aimed to assess some aspects of the reproductive biology of the two species (Puntius tumba and Anabas testudineus) that are endemic and threatened, respectively. Monthly assessment was carried out to determine variations in sex ratio, gonadosomatic index (GSI), and stages of oocyte maturation as a measure to determine absolute fecundity (AF). Both species showed a female-favored population in most times of the year except in July for P. tumba and March and June for A. testudineus. The five stages of oocytes maturation were immature, maturing, mature, ripe, and spent. The peaks in GSI and estimated AF in May, August and September indicate the approximate spawning periods of P. tumba while the peaks in GSI and estimated AF in November, March and April indicate the spawning periods of A. testudineus. No significant relationships were observed between the GSI to the body and gonad lengths and between fecundity with those of the body and gonad lengths which indicate constancy of body length despite periodic variations of fecundity. In conclusion, the breeding-to-maturation periods were predicted to be in September to April for P. tumba and June to October for A. testudineus. This conservative estimate could be less predictive for P. tumba than that of A. testudineus as limited samples for P. tumba were obtained in most of the months.
