Abstract
The reproductive seasonality of Puntius schwanenfeldii from the Perak River, Malaysia was investigated over a 19 month period. Females greater than 160 g had mature or rematuring ovaries, and males of all sizes had mature testes throughout the study period. Analysis of female reproductive condition was based upon the presence of post ovulatory follicles (POF), the gonadosomatic index (GSI) and the volume fraction of stage IV oocytes (IV%), and GSI and presence of tubercles for males. Recrudescence followed immediately after ovulation, which allowed the use of objective thresholds to identify recently spawned females during the GSI and IV% recovery period. GSI and IV% were the best indicators of reproductive patterns as a result of their recovery period being longer than for POF. Male tubercles and GSI showed some statistically significant variation, but no clear relation with observed changes in female indicators. Reproduction was apparently aseasonal, and this pattern is likely an effect of flow regulation by dams which have virtually eliminated the dominant flood period and most seasonal flow variation. Hypothesized shifts in the reproductive seasonality due to flow regulation are consistent with predictions based on life history theory under conditions of altered environmental seasonality.
Published Version
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