Length-Weight Relationship, Condition Factor and Food and Feeding Habits of Seriola Dumerili (Risso, 1810, Carangidae) In Al-Hamama, Eastern Libya Mediterranean Sea

Abstract

Stomachs of 235 pre-adult (PA) and 111 adult (A) Seriola dumerili obtained monthly from Al-Hamama (eastern Libya Mediterranean Sea) artisanal catch during November 2012 to October 2013 were examined to study food and feeding habits of the fish. The length-weight relationships of “PA” and “A” were W = 0.0437L2.819, n = 235, R2 = 0.99 and W = 0.019L2.873, n = 111, R2 = 0.99, indicating isometric growth. Annual ranges of monthly values of Fulton (KF) and Clark (KC) condition factors were 2.35 to 3.1 and 1.71 to 2.52 for “PA” and 0.98 to 1.44 and 0.69 to 1.22 for “A” in order. Relationships of both factors with fish length and months and seasons of the year were established. “PA” KF and KC recorded highest values in autumn and spring, which coincided with the period of highest degree of stomach fullness. “A” KF and KC recorded highest values in spring and summer, which coincided with the period of stomach fullness in spring and the spawning season in summer. Food items of “PA” according to order of importance were crustaceans, mollusks, polychaetes, sea grass and bony fish. Those of “A” were bony fish, mollusks, crustaceans, sea grass and polychaetes. Dependence of “PA” on crustaceans, mollusks and bony fish increased with increasing fish length while that on the other items decreased. Dependence of “A” on bony fish and mollusks increased with increasing fish length while dependence on the other items decreased. “PA” prefers feeding on crustaceans and sea grass in summer, on mollusks and bony fish in spring and on polychaetes in autumn. “A” prefers bony fish in autumn and summer, mollusks and polychaetes in spring, crustaceans in winter and sea grass in summer. Monthly and seasonal feeding intensity were established. The feeding intensity was high during autumn and spring for “PA” and moderate to high during all seasons for “A”.

Keywords: Condition Factor, Feeding Habits, Food, Length-Weight Relationship


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