Articles written in Proceedings – Animal Sciences
Volume 93 Issue 2 March 1984 pp 97-106
The fish matured only after attaining an average length of 700 to 770 mm. The period between July to September was established to be its spawning season. Observations on the Gonado-Somatic Index (GSI) and relative condition factor confirmed this observation. The variation in the sex-ratio during the spawning season was considered to be a remarkable adaptation towards low fecundity. The paper also comments on the problems of the Garhwal Himalayan mahseer and precautionary methods awaiting implementation in this region.
Volume 93 Issue 7 December 1984 pp 671-674
Seasonal fluctuations along with certain physico-chemical parameters were recorded for two hillstreams, the Alaknanda (snow-fed) and the Nayar (spring-fed). In the former, the water temperature range of 9–14°C is considered optimum for the growth of diatoms, compared to 12–21°C in the Nayar. In both hillstreams diatoms achieved their maxima during January, when the water temperature is the lowest. Sudden influx of rain water carrying enormous silt during monsoon is responsible for the decline in density. The water temperature and current, especially the latter is thus a detrimental factor. The interesting feature of the study is, the relatively higher percentage of diatoms in the Nayar than in the Alaknanda, obviously to be attributed to the warm waters in the former.
Volume 95 Issue 6 December 1986 pp 751-756
A technique to sample plankton efficiently in the fluvial systems is being propounded along with a note on the need and design of the plankton sampling device suited to torrential reaches. The technique, christened as discharge-time method, has certain advantages. The requirements are minimum (detachable bucket of the conical plankton net with bolting silk cloth of required mesh size) and the efforts are nominal. In order to sample plankton the device has to be dipped into the river with its open end facing the current, for a pre-calculated period of time. The formula, ‘