ON THE ACCURACY OF THE PELLET ANALYSIS METHOD TO ESTIMATE THE FOOD INTAKE IN THE ANTARCTIC SHAG Phalacrocorax bransfieldensis.

CASAUX R.

Workshop; The CCAMLR Ecosystem Monitoring and Management Working Group; 1997

The accuracy of correction factors estimated to compensate the digestion and loss through the gastrointestinal tract of the otoliths of fish represented in pellets of the Antarctic Shag Phalacrocorax bransfieldensis was tested at two localities of the South Shetland Islands. For such purpose, the results from the analysis of 226 and 115 pellets collected at Harmony Point and at Duthoit Point, respectively, throughout the breeding season were compensated with the mentioned factors. The estimations indicated that the daily food intake increased from November to January (pre-laying to late-rearing) and slightly decreased in February. These estimations, in general, are in line with those previously obtained for other colonies and/or shags by different methods, which suggests that the use pellets is an acceptable method to quantify the diet of the Antarctic Shag.