Xchel Gabriel Moreno Sánchez

Diet of the cortez damselfish Stegastes rectifraenum (teleostei:Pomacentridae) from the rocky reef at Los Frailes, Baja California Sur, Mexico

The stomach contents of 50 Cortez damselfish Stegastes rectifraenum captured at Los Frailes, Baja California Sur, Mexico were analysed to describe their diet. According to our results, S. rectifraenum is an omnivorous species with a preferente for certain prey; invertebrates (benthic copepods) and algae (Bryopsis spp. and Ectocarpus spp.). Other animal components (Cerithium spp. and Olivella spp.) can also be found in their diet. No differences were observed between genders (analysis of similarity (ANOSIM), R 1⁄4 0.002, P 1⁄4 0.001) or among seasons (ANOSIM, R 1⁄4 0.046, P 1⁄4 0.001), therefore their food can be available all year at the rocky reef at Los Frailes.

Diet of the yellowfin snook, Centropomus robalito (Actinopterygii: Perciformes: Centropomidae), in the southwestern Gulf of California

Information on the diet of fish is necessary to understand their role in trophic webs in a given space and time (Gerkin 1994). The diet of predators is influenced by multiple factors, such as prey availability, mobility, abundance, environmental factors, and the developmental stage and sex of the predator, which have been identified as determinant of the ecological importance of each species in the trophic web in which they participate (Braga et al. 2012, Navia et al. 2012). Species of the genus Centropomus are characterized as being active nocturnal predators that feed on crustaceans and coastal fish (Adams et al. 2009, FeltrinContente et al. 2009). The yellowtail snook, Centropomus robalito Jordan et Gilbert, 1882, is the most abundant species of the Centropomidae family captured as bycatch in shrimp fishery of the southwestern Gulf of California. It also represents one of the most important artisanal fisheries, traditionally being caught by coastal fishing communities in the Mexican states of Nayarit and Sinaloa ACTA ICHTHYOLOGICA ET PISCATORIA (2015) 45 (1): 21–29 DOI: 10.3750/AIP2015.45.1.03

Icthyodiversity of San Jose, San Francisquito, and El Pardito islands in the southwestern Gulf Of California, Mexico

The San Jose and San Francisquito Islands and El Pardito Islet are important for recreational tourism, sport fishing, and commercial fishing. They are part of an “Area Natural Protegida” and “Area Prioritaria Marina”; however, studies on the composition and diversity of their marine floral and faunal communities are limited. To provide information vital for management and conservation of these islands, a check-list of the ichthyofauna was compiled based on original data and the data extracted from other sources.

Variation of feeding habits of [i]Lutjanus Peru[/i] (Actinopterygii: Perciformes: Lutjanidae) caught in two regions of the Gulf of California, Mexico

Background. The Pacifi c red snapper, Lutjanus peru (Nichols et Murphy, 1922), is one of the most exploited species by artisanal fi sheries in Mexico, where it is valued due to its high catch rates and economic value. This study investigated the feeding habits of L. peru in two ecosystems of the southern Gulf of California with contrasting physical and oceanographic conditions. Feeding habits were compared by sex (male or female), size (juvenile or adult), and season (cold or warm), in order to determine whether this species plays the same trophic role in the two ecosystems. Materials and methods. Samples were obtained from the northern Sinaloa coast (SIN region) and south-eastern Baja California Sur coast (BCS region). Percentages by number, weight, and frequency of each food category were determined, and the index of relative importance (%IRI) was calculated to defi ne the main food categories. Diet breadth and diet similarity between sexes, sizes and among seasons were also calculated. Results. A total of 182 stomachs from the SIN region were analysed and 32 prey items from 15 families, 18 genera, and 25 species were identifi ed. According to the index of relative importance (IRI), the most important prey items were the shrimp, Penaeus californiensis (73%); the ostracods, Myodocopida gen spp. (10%); and the squid, Loligo spp. (5%). A total of 233 stomachs from BCS were analysed and 31 prey items from 17 families, 19 genera, and 26 species were identifi ed. The most important prey items according to the IRI were the red pelagic crab, Pleuroncodes planipes (42%); the ostracods, Myodocopida gen spp. (28%); and the shrimp, Penaeus californiensis (20%). Signifi cant differences were identifi ed in the trophic spectra by region, size and season. There were no signifi cant differences by sex. Conclusion. Lutjanus peru displayed a specialist trophic behaviour, with differential utilization of the trophic niche and adequate food resource distribution.