Document Type : article
Authors
1
Inland Waters Aquaculture Research center, Iranian Fisheries Science Research Institute (IFSRI), Agriculture research Education and Extension Organization (AREEO), Bandar-e Anzali, Iran
2
Iranian Fisheries Sciences Research Institute. Agricultural Research, Education and Extension Organization, Tehran, Iran
3
Inland Waters Aquaculture Research center, Iranian Fisheries Science Research Institute (IFSRI), Agriculture research Education and Extension Organization (AREEO), Bandar-e Anzali, Iran.
Abstract
Northern pike is the second most economically valuable fish species in Anzali lagoon which annually is caught 50 to 180 metric tonns in the area. The study of feeding regime of immature individuals of Esox lucius has been carried out in Anzali lagoon from April 2006 to March 2007. The main aims of the study were to determine the ecological role of the species in the area in order to manage its stock and elevate awareness level of fish culturists, too. Totally, 246 specimens of 0+ to 2+ years old with the total length 5.5 to 41.2 cm and weight 1.1 to 1438.0 g , respectively were studied. The results showed that the vacuity index was 17.9%. The mean length of gastrointestinal tract was 0.93±0.11 (mean±S.D) The mean fullness intensity index was 374.3±456.8 which showed a significant difference in different seasons, ages and stations (p <0.05). The study found that the young pikes in the Anzali lagoon fed 40 taxa of animals that fish had the most diversity, indicating euryphagous feeding behavior. Carassius gibelio, Proterorhinus nasalis, and freshwater prawn, Macrobrachium nipponense, were identified as secondaryfood items with 12.4%, 12.4% and 10.4%, respectively and these preys had the most relative importance in pikes growth, with 52.8%, 16.0% and 8.1% respectively. The present study showed that pike feeds especially more abundant, low-mobility and medium-sized preys, throughout the year, so that adequate prey should be provided for their breeding in order to decrease cannibalism risk.
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