The natural diet of the green abalone (Haliotis fulgens Philippi) in the southern part of its range, Baja California Sur, Mexico, assessed by an analysis of gut contents

An attempt was made to assess the natural diet of the green abalone from the southern extreme of its range by examination of gut contents. Crop and stomach contents were identified in samples from study sites at Bahia Asuncion, La Bocana, Punta Abreojos, and Las Barrancas along the Pacific Coast of Baja California Sur. Shell lengths of abalone from banks at the northern sites, Bahia Asuncion and La Bocana, were greater than for abalone found at the southern sites, Punta Abreojos and Las Barrancas. The consistency and weight of gut content among individuals varied according to the extent of digestion in each. Differences were found between the weight of the particulate contents at the different sites. The smallest number of plant species in the gut was one, and the largest was six. The average number of plant species per individual gut was similar at three sites. The highest average was at Las Barrancas. Seven Rhodophytes, four Phaeophytes, and one seagrass were recorded. The number of species in samples from Las Barrancas was nine, followed by Bahia Asuncion (n = 8), La Bocana (n = 7), and Punta Abreojos (n = 5). The most common food items in gut content were the seagrass Phyllospadix torreyi and the macroalgae Sargassum sp., Eisenia arborea, Cryptopleura crispa, and Rhodymenia sp. The other species found in the abalone diets could be considered species that are consumed incidentally with the main food according to the local flora. The brown algae Sargassum and Eisenia and the red algae Cryptopleura and Rhodymenia made up about 50% (relative frequency) of the recovered food items at Bahia Asuncion and Las Barrancas and about 80% at La Bocana and Punta Abreojos. P. torreyi formed 32% of the recovered food items at Punta Prieta and about 15% at the other sites. No other algae formed more than 12% of the gut content items in these green abalone.