Food Habits, Length-Weight Relationship, Condition Factor, and Growth of Juvenile Red Drum, Sciaenops ocellata, in Louisiana

Abstract

Food habits of 568 juvenile red drum, Sciaenops ocellata (Linnaeus), ranging from 8.0 to 183.0 mm standard length, were determined during the time the fish utilized a Louisiana salt marsh as a nursery area. Potentially available food organisms were sampled during the 7-mo study. Some degree of selectivity by juvenile red drum was demonstrated, but generally the most abundant organisms of an edible size were utilized most heavily. Changes in food with increasing size can be described in three phases: 1) red drum less than 15 mm ate zooplankton; 2) between 15 mm and 75 mm the red drum ate mostly small bottom invertebrates and the young of other fish; 3) red drum larger than 75 mm ate decapods (crabs and shrimp) and fish. Some differences between day and night feeding were found. For red drum 65 to 85 mm the dominant food eaten was grass shrimp during the day, whereas at night it was fish. The length-weight relationship was log W = −7.2052 + (4.1913) (log L). The average coefficient of condition was 1.969. Average growth per month ranged between 13.8 and 25.6 mm during the study period.