Feeding behavior of lessepsian fish Etrumeus teres (Dekay, 1842) from the Mediterranean Waters, Egypt

The present work studies the food and feeding habits of lessepsian fish, Etrumeus teres (Dekay, 1842) to know its feeding behavior in relation to sex, length and season as well as its preference for food items. Fish samples were collected monthly from Alexandria landing centers during 2008 and a total of 490 individuals were selected to be examined for this study. The results indicated that round herring E. teres feeds on a variety of food materials mainly small crustaceans (shrimp larvae, isopods and amphipods) followed by fish larvae (Engraulidae, Mugilidae and Labridae); Mollusk (few gastropods and cephalopods) as well as food remains. The feeding intensity showed the highest values during winter and spring (82% and 50.55%, respectively) while the lowest values were during summer and autumn (40.14% and 38.1%, respectively). Round herring E. teres shifted their fullness index as they grow in length where the lowest value of this index was recorded for a length group of 9–15cm TL and the highest value was recorded for a length group of 15–20cm TL. According to the modified food index (MFI), crustaceans were the first preferable food item represented mainly by shrimp larvae (61.69%) followed by fish larvae which were represented mainly by Engraulids (23.58%). Diversity index (H′) of food items for males was higher than females; while this index (H′) for the small length group (9–15cm) was higher than the other length groups which suggest that fishes of smaller length seemed to be more active in capturing different food items. Also, the value of diversity index (H′) of Autumn was higher than other seasons. The overlap test (T) showed no obvious differences between males and females and between different length groups where the value was found to be “1” indicating that all fishes have the same mode of feeding. Food items were attracted and aggregated by artificial light of purse-seine using light giving a positive effect of this fishing method for pelagic fishes particularly E. teres to feed on those materials. From the previous findings, it can be speculated that, round herring E. teres from the Egyptian Mediterranean Waters is zooplanktivorous.