Jesús Rodríguez-Romero

Diet of blue marlin Makaira mazara off the coast of Cabo San Lucas, Baja California Sur, Mexico

Abstract Analysis of the stomach contents of 204 blue marlin ( Makaira mazara ) caught by the sport-fishing fleet of Cabo San Lucas in the southern Gulf of California is presented. The specimens sampled were caught during the summer and fall of 1987, 1988, and 1989 when the sea is warm (28–30°C). Blue marlin were found to feed on 35 prey species, 3 of which represented 90% of the total stomach contents by frequency of occurrence. The main prey were epipelagic organisms from the oceanic zone and demersal fishes from the neritic zone. The most important prey were bullet mackerel Auxis spp., young finescale triggerfish Balistes polylepis , and the giant squid Dosidicus gigas .

Preliminary Study on the Effect of Stocking Density on the Growth and Survival of the Yellow Snapper Lutjanus argentiventris Confined in Cages in a Tidal Pond

Abstract The effect of stocking density on the growth and survival of the yellow snapper Lutjanus argentiventris when confined in 1-m3 cages in a tidal pond for 125 d was investigated. Test densities were 6, 9, and 12 fish/m3 with three replicates each. Preliminary results indicated that density of 6 fish/m3 had a significant difference in growth (P 0.05). In general, survival was above 90%, with the exception of the lowest density.

Feeding habits of Mustelus henlei on the western coast of Baja California Sur, México

Palabras clave: Contenido estomacal, superposicion de dieta, especialista, Punta Lobos, Baja California Sur, Mexico Abstract.- The Brown smooth-hound Mustelus henlei is part of an important commercial fishery on the western coast of Baja California Sur (BCS), Mexico. However, very few studies have been performed on the feeding and reproduction biology of these sharks in Mexico. Our study is the first work focusing on this species on the western shelf (14 m to 250 m in depth) of B.C.S. We identified a total of 24 types of prey contents in the stomachs of M. henlei: 15 crustaceans, 6 fish, and 3 cephalopods. According to the index of relative importance (IRI) the main prey items for M. henlei was the pelagic red crab Pleuroncodes planipes (81.4%), followed by unidentified organic material (UOM) (15.7%), the mackerel Scomber japonicus (0.94%), and fish remains (0.84%). Conducting a prey analysis considering sex of M. henlei, P. planipes was the most important prey in both females and males, followed by UOM, and S. japonicus. Sharks found in deeper areas (120-150 m) and those caught on board the exploration ship BIP XII had a similar dietary composition to those found in the shallow waters of Punta Lobos (14-40 m) where for both regions, the dominant prey items were the pelagic red crab and UOM. According to Levins index, M. henlei may be a specialist feeder in this area. A diet overlap according to sex, area, and size was observed. The SIMPER analysis showed a low similarity in diet in relation to sex, size, and area. According to the ANOSIM test there were no significant differences. Knowing that M. henlei shows a specialist behavior could help research studies not only for species conservation but also for its habitat and the organisms that inhabit it, which are both of vital importance for this shark.

Trophic spectrum of the juvenile roosterfish, Nematistius pectoralis Gill, 1862 (Perciformes: Nematistiidae), in Almejas Bay, Baja California Sur, Mexico

Este trabajo es la primera contribucion al conocimiento de la dieta del Pejegallo Nematistius pectoralis, capturado en Bahia Almejas, Baja California Sur, Mexico. Se describe cualitativa y cuantitativamente el espectro trofico de 59 ejemplares de N. pectoralis, usando los metodos tradicionales de frecuencia de aparicion, numerico y peso, asi como el indice de importancia relativa. En Total se identificaron 10 especies presa de las cuales 9 fueron peces y un cefalopodo. Se determino que el pejegallo, es un depredador ictiofago activo el cual incide principalmente sobre especies de peces que forman cardumenes como los son Eucinostomus dowii, E. gacilis, Anchoa ischana y Anchoa spp.

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.

General characteristics of diet of the raucous grunt, Haemulopsis leuciscus (Perciformes: Haemulidae), in Bahía Almejas, Baja California Sur, Mexico

The food habits of 81 organisms of the raucous grunt Haemulopsis leuciscus were analysed. The organisms were captured in Bahia Almejas, Baja California Sur, Mexico, during five bimonthly samplings (March–November 1998). The index of relative importance indicated that H. leuciscus consumed a total of eight prey-items, and the dominant prey were the gastropod Oliva spp., Conus spp., and scaphopod Dentalium spp.

Ampliaciones de ámbito Vol.41 (3B)

Inflorescences of Baclris gasipaes (a moooecioos neolropica1 pahn) present a strong prezigotic resource allocation toward masculinity on the inflorescence. Male reproductive effort (ERM. biomass) was 0.82 ± 0.11 g male flowers / g inflorescence. A high conelatioo between me total inflorescence biomass with female reproductive effort (ERF) (r= 0.76), indicates that plants wim bigger inflorescences allocate more resources to ihe female functioos. The pistillate flowers are situated preferentially in me inner pans of rachillas. Early ideas about evolution of protoginy, resource allocation and plant sexual systems are supported by these data.

First record of spine malformation of the round stingray Urobatis halleri off the Western Coast of Baja California Sur, México

BackgroundMalformations of the Round stingray Urobatis hallerii, Cooper 1863 captured off the southwestern coast of Baja California Sur, México are reported in this study.MethodsThe ray was an adult male captured by artisanal fishery in the area of Estero Banderitas. Size measurements of total length and disk width were taken; the organism could be photographed when captured.ResultsMalformations of U. hallerii were found in the posterior part of the spine, a distortion in the upper part of the tail and in the left fin close to the tail. The specimen was considered able to reach the adult size usually reported in other specimens of this species despite the spine malformations because of its benthic habits and not losing its mobility completely.ConclusionsThe observed malformations were likely due to genetic alterations although other studies are needed to see if other environmental factors could cause malformations in marine organisms mainly in fish and elasmobranchs.