Further observations on polyculture of finfishes andudPrawns in saltwater ponds and in a net-pen at Mandapam

摘要

The paper deals with the results of polyculture experiments with milkfish.udmullets, Sillago and prawns in salt water ponds and in a netpen in the coastaludwaters of Palk Bay at Mandapam, during the period 1979-82. The growth ofudmullet and Sillago was better in the netpen than in the pond, whereas milkfishudshowed better growth in the pond. Significant differences in production from fertilizedudand unfertilized ponds have not been noticed, the result of which is attributedudto poor soil conditions of the farm. Mullets sharply reacted to low levels of oxygenudin ponds. During 1979-80 period, in experiment I, the production per hectare wasud671.1 kg for Chanos chanos, 68.9 kg for Valamugil seheli, 593. 3 kg for Liza macrolepisudand 31.1 kg for Penaeus indicus, thereby recorded the total of 1364.4 kg.udIn experiment II, the production was 1286. 7 kg for C. chanos, 551.1 kg for V.udseheli md 26.7 kg for Sillago sihama with the total of 1864.5 kg. In 1980-81 experiment,udthe total production was 1600 kg with the combination of 1266.7 kg C.udchanos and 333.3 kg V. seheli in the fertilized pond and 1422.2 kg with the combinationudof 1205.5 kg of C. chanos and 216.7 kg of V. seheli in the unfertilizedudpond. During 1981-82 period, the total production was 1377.8 kg in which C. chanosudshowed 1288.9 kg and V. seheli 88.9 kg in the fertilized pond, and in the unfertilizedudpond it was 1469.9 kg with 1405.5 kg of C. chanos and 64.4 kg of V. seheli.