Abstract

Information was gathered on seasonal variation of two condition factors of red snapper, Lutjanus campechanus, taken from the Louisiana (LA) continental shelf banks. Red snapper were collected from September 2011 to October 2013 from three natural banks on the LA shelf, those being Jakkula, McGrail, and Bright, and one artificial reef in the East Cameron Artificial Reef Planning Area. The two condition factors chosen were the liver-somatic index (LSI) and caloric density. LSI was calculated as the proportion of liver weight to eviscerated body weight. Caloric density of fish muscle tissue was estimated directly with a Parr 6200 oxygen bomb calorimeter. In general, LSI began to increase from De-cember- March, peaked in May, and declined thereafter until October. LSI differed between natural and artificial reefs, and the LSI was higher in females, indicating more energy invested towards reproduction. The caloric density of red snapper exhibit a similar pattern to that of the LSI, but the trends were not as clear, owing to significant annual variabil-ity. The caloric density was higher in 2012 compared to 2013, indicating that red snapper were able to store more ener-gy within their muscle tissues in 2012. The caloric density of red snapper from the sites with coral substrate (Bright and McGrail) was generally lower from that of the non-coral substrate sites (Jakkula and East Cameron). Red snapper appear to be using energy stores from both the liver and muscle tissue for reproduction and the site-specific differences seen may be attributable to dietary and environmental factors.

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