Scielo RSS <![CDATA[Latin american journal of aquatic research]]> vol. 45 num. 5 lang. en <![CDATA[SciELO Logo]]> <![CDATA[A suitable ichthyometer for systemic application]]> ABSTRACT An excessive and inappropriate handling of live fish is currently performed to obtain its size and weight. As an ameliorative attempt, a system named “IchthyoJHOL” was devised for the measurement of live specimens of fusiform fish species. The system holds the fish ventrally between supports and is mounted upon a scale. An image is captured on camera and processed with a digital measurement system. The system generates biometric data such as length, height, and weight. This methodology creates a two-stage biometric process, the first being the capture of the images and the second their digital analysis, allowing for each stage to be carried out at distinct times and places. With this methodology, a reliability of over 96.8% is achieved, similar to that produced by the traditional system, but with a significant reduction in handling time and stress induced on the fish, allowing for large-scale biometric analysis. In addition, the library of fish images can be shared for posterior evaluation, redescription studies or a more extensive morphometric analysis. <![CDATA[Diet and trophic organization of the fish assemblage from the Mamanguape River Estuary, Brazil]]> ABSTRACT The present work aims to characterize a fish assemblage from a northeastern Brazilian estuary according to its diet and trophic organization along the estuarine-reef gradient. Sampling was performed at the Mamanguape Estuary, and fishes were collected using three types of nets at seventeen sites, grouped into four regions according to salinity range: reefs and the lower, middle, and upper estuary. The most abundant species were Atherinella brasiliensis, Mugil curema, and Sphoeroides testudineus. The highest species abundance and richness was observed for the lower estuary. Zooplankton was the most consumed category, recorded for forty-two species. Among the guilds, piscivores were the most abundant, followed by crab eaters. Herbivores, mostly represented by Abudefduf saxatilis, had a higher abundance in reefs, being correlated according to ANOSIM analysis to this region, while piscivores and crab eaters showed a high contribution to inner regions of the Mamanguape Estuary. <![CDATA[Stocking density for freshwater prawn <em>Macrobrachium rosenbergii</em> (Decapoda, Palaemonidae) in biofloc system]]> ABSTRACT The objective of this study was to evaluate the effect of stocking densities on productive performance of the freshwater prawn Macrobrachium rosenbergii in biofloc system. Experimental tanks (microcosms) with 0.20 m2 area were used as experimental units. The tanks were connected to two 300 L matrix tanks (macrocosm) with biofloc technology, used as recirculating units. M. rosenbergii juveniles, with an initial weight of 0.315 ± 0.06 g and initial length of 33.34 ± 2.26 mm, was randomly distributed in the experimental tanks at different stocking densities (50, 100, 150, 200 and 250 ind m-2) and reared during 60 days. The total biomass at the end of the experiment was significant higher (P &lt; 0.05) with the use of higher stocking density (250 ind m-2). However, prawns stocked at the density of 50 m-2 showed significant higher (P &lt; 0.05) survival (73%) and significantly lower values (P &lt; 0.05) for feed conversion rate (1.28). The different stocking densities evaluated did not affect the weight and length of prawns. The recommended density for growing M. rosenbergii in the biofloc system is 50 ind m-2. <![CDATA[Effects of bacilli, molasses, and reducing feeding rate on biofloc formation, growth, and gene expression in <em>Litopenaeus vannamei</em> cultured with zero water exchange]]> ABSTRACT The effects of reducing feeding rate and molasses on water quality, growth, and gene expression of Litopenaeus vannamei were evaluated in a super intensive system with zero water exchange. A bioassay of 35 days (0,75 ± 0,22 g, 36 shrimp tank-1, 450 shrimp m-3) with treatments in triplicate was performed: I) 100% commercial feed (control group) with water exchange; II) 100% commercial feed without water exchange; III) 100% commercial feed + Bacillus licheniformis BCR 4-3 + molasses without water exchange; IV) 90% commercial feed + B. licheniformis BCR 4-3 + molasses without water exchange, and V) 80% commercial feed + B. licheniformis BCR 4-3 + molasses without water exchange. Shrimp survival, weight, nitrogenous wastes, settleable solids (SS), and the relative expression (RT-qPCR) of stress and digestive genes were determined. Shrimp survival was 100% in all treatments. The reduced diet, bioflocs, and bacilli did not affect shrimp growth. The culture conditions reduced nitrogenous wastes and modulated mRNA expression of trypsin, chymotrypsin, and heat shock protein 70. Reduced feed ration can help to maintain water quality and lower costs in intensive shrimp cultures with bioflocs. <![CDATA[Effect of <em>Passiflora incarnata</em> (L) extract on gonadal maturation in young tilapia (<em>Oreochromis</em> sp.)]]> ABSTRACT The effect of Passiflora incarnata's extract (PE) on gonadal maturation in young tilapia (Oreochromis sp.) was evaluated by administering feed supplemented with PE during the first 90 days immediately after yolk sac assimilation. One hundred and fifty fishes with 0.01 ± 0.003 g average body weight were randomly distributed in ten tanks with the following duplicated treatments: commercial feed (NAT), NAT with 60 mg kg-1 of 17-MT (MET), and NAT supplemented with 31.10 mg, 62.30 mg and 124.60 mg of PE g-1 (P1, P2, P3 respectively). There were no significant differences (P &gt; 0.05) in the average body weight or in the male-female sex ratio between the experimental treatments (P1, P2, P3) and the control (NAT). Statistical differences in the gonadosomatic index (GSI) and the percentage distribution of gonadal maturation stages (PDGMS) were observed in females of P2 and P3. With respect to the females of NAT, the treatments P2 and P3 presented a lower GSI and a lower percentage of females in stage III (GSI: 1.11 ± 0.88, 1.04 ± 0.99 and 1.71 ± 0.72; PDGMS: 45, 30 and 80%, respectively). No significant differences in GSI or PDGMS were observed in the males. The results suggest that the observed differences in GSI and PDGMS in females are unrelated to antinutritional effects. Instead, these differences could be due to a possible antiestrogenic effect attributed to the possible anti-aromatase action of some of its compounds. Future research focusing on the use of PE for reproductive control in tilapia is suggested. <![CDATA[Cornstarch as a dietary supplement in conditioning broodstock and spat at a nursery of the Pacific calico scallop, <em>Argopecten ventricosus</em>]]> ABSTRACT Microalgae diets supplemented with cornstarch at a rate of 0.15% of live weight to the conditioning of broodstock and spat growth of Pacific calico scallop Argopecten ventricosus were tested. To determine reproductive condition at the beginning and end of the experiment, the gonads of adults were analyzed by stereological methods. For juveniles, the weekly percent increase of spat was estimated from spat biomass volume. The microalgae diet of Tisochrysis lutea and Chaetoceros calcitrans, supplemented with cornstarch, substantially improved the reproductive status of the scallop, particularly by increasing the number of individuals in mature and mature-spawning stages with more mature oocytes by the scallop. Spat growth improved &gt;80% in the nursery with the diet supplemented with cornstarch compared with the microalgae diet (T. lutea, C. gracilis, and C. calcitrans). It can be suggested that a small addition of cornstarch to a microalgae diets, boosts growth during nursery procedures and performance of A. ventricosus during the routine conditioning of the broodstock. <![CDATA[Evaluation of two mix-cultures of white shrimp (<em>Litopenaeus vannamei</em>) with red tilapia hybrid and spotted rose snapper (<em>Lutjanus guttatus</em>) in intensive indoor brackish water tanks]]> Abstract The aim of this study was to evaluate the growth performance and survival of the Pacific white shrimp (Litopenaeus vannamei) with red tilapia hybrid (Red Florida: Red Yumbo) and spotted rose snapper (Lutjanus guttatus), stocked at different densities in intensive brackish water mix-culture systems compared with monoculture of shrimp. The experiment, conducted in twenty-one plastic tanks (750 L) was set up to evaluate water quality, growth; production and survival of shrimp, tilapia, and snapper, for 60 days. Three replicates were assigned to seven treatments: After 30 day, initial densities were unfolded (shrimp = 50 ind m−3, tilapia = 16 ind m−3 and red snapper = 8 ind m−3). Feeding rate was adjusted at 5 and 10% of body weight d−1 for shrimp and fish, respectively. The shrimp-tilapia mix cultures produced the higher nitrogen and phosphorus in water concentrations. Significant lower survival values were obtained for shrimp (60.0 ± 0.6%) cultured with snapper and for tilapia (79.0 ± 3.1%) reared with shrimp. Mean final biomass for shrimp, tilapia and snapper were higher for the mix-cultures (2.04, 7.7 and 2.9 fold increase, respectively) with respect to their initial biomass. The mix culture system allowed an increase in total production with lower feed conversion ratios, thus contributing with the system sustainability. <![CDATA[Levels of 17β-estradiol, vitellogenin, and prostaglandins during the reproductive cycle of <em>Oreochromis niloticus</em>]]> ABSTRACT Circulating levels of estradiol, vitellogenin and prostaglandins could be references of oocytes quality in the aquaculture industry. This study evaluated the performance of 17β-estradiol (E2) and vitellogenin (Vtg) levels in plasma and prostaglandins in oocytes (PGE 2) during the reproductive period of Oreochromis niloticus in a commercial farm in Ecuador. Adults fish females were treated with estradiol-synthetic (ES) and tilapia pituitary extracts (TP) during 25 days. For quantification of E2 and PGE 2, an enzyme-linked immunosorbent assay (ELISA) was used, while for Vtg relative quantification a Western blot analysis was performed. Circulating E2 concentrations were different during the first week of follow-up (P &lt; 0.05) resulting in different levels of Vtg per treatment (P &lt; 0.05) affecting on gonadal growth. The ovaries had an asynchronous development, where the mature oocytes proportions were higher with ES and TP than control. Relative fecundity was different between treatments (P &lt; 0.05), where TP generated 15.7 ± 5.8 oocytes per g of spawning female. Furthermore, concentrations of PGE 2 were different between treatments (P &lt; 0.05). The information reported in this study will be useful to improve the reproduction methods and have some biological signals before ovulation in tilapia commercial culture. <![CDATA[Potential of refrigerated marine cyanobacterium <em>Synechococcus elongatus</em> used as food for <em>Artemia franciscana</em>]]> ABSTRACT The aim of this study was to evaluate the performance of the cyanobacterium Synechococcus elongatus after refrigerated storage (4°C) and examine its potential as food for Artemia franciscana. Non-axenic semicontinuous cultures of S. elongatus were maintained at 4°C for 8 weeks. In our bioassay, we fed A. franciscana with refrigerated S. elongatus and fresh cultures of the diatom Chaetoceros muelleri as a control. The S. elongatus cultures could be refrigerated for up to 8 weeks without loss of its viability or alteration in its growth rate, cell size, and proximate composition. Fresh and eight week-refrigerated cultures of S. elongatus were similar with regard to fatty acid profiles. Significant differences in fatty acid profiles were found between refrigerated S. elongatus and fresh C. muelleri cultures. Vibrio bacteria were not detected in any of the S. elongatus cultures (fresh or refrigerated) or fresh cultures C. muelleri. This work demonstrated that refrigerated S. elongatus can be used to feed A. franciscana, maintaining similar growth rates and proximate composition compared with fresh C. muelleri cultures as feed. Thus, S. elongatus has potential aquaculture use as feed for A. franciscana. <![CDATA[Protozoan parasites of freshwater ornamental fish]]> ABSTRACT The ornamental fish aquaculture represents a consolidated market worldwide. In Brazil, the major volume of commercialized freshwater ornamental fish is originated from fish farms managed by small and midsized farmers. The aim of this study was to characterize the metazoan parasitic fauna associated with the main freshwater ornamental fish farmed in Southern Brazil. Between July 2014 and January 2015, 423 fishes belonging to nine freshwater species were examined: angelfish Pterophylum scalare, siamese fighting fish Betta splendens, telescope and comet goldfish Carassius auratus, zebrafish Danio rerio, blood red swordtail Xiphophorus helleri, caramel and wagtail platy fish Xiphophorus maculatus, black molly Poecilia sphenops, white cloud mountain minnow Tanichthys albonubes and goldfinned barb Puntius sachsii. Water quality was measured in fishponds from each facility. Specimens were obtained from three ornamental fish farms located in three micro-regions in the State of Santa Catarina (Biguaçu, Camboriú e Joinville). Parasitological indexes were obtained after parasitological analysis of mucus, gills, and eyes. Trichodinids, Piscinoodinium pillulare, and Ichthyophthirius multifiliis were found in all fish farms analyzed. However, P. pillulare showed the greatest prevalence and mean intensity, compared to the other protozoa analyzed. 75% prevalence and mean intensity 57.5 were observed in the gills of P. scalare from fish farm Araquari. This study showed that fish farm Biguaçu, was the facility presenting the greatest parasite diversity. P. scalare and C. auratus were the most parasitized fish species presenting the higher richness when compared to another species. These ornamental species are widely traded and require greater care in cultivation because it is essential to produce healthy fish with attractive features accepted by the market. <![CDATA[Abundance estimate of the Amazon River dolphin (<em>Inia geoffrensis</em>) and the tucuxi (<em>Sotalia fluviatilis</em>) in southern Ucayali, Peru]]> ABSTRACT We present results of the first simultaneous visual and acoustic surveys for Amazon River dolphins (Inia geoffrensis) and tucuxi (Sotalia fluviatilis), undertaken in Yarinacocha Lagoon, Ucayali, Peru (length = 20 km, area = 12 km2). A total of 324 Sotalia observations and 44 Inia observations were recorded in boat-based transects. Based upon total survey effort, we estimated Sotalia had a mean density ± SE of 1.98 ± 4.6 ind km−2 and an overall abundance of 34 individuals (95% CI: 28 to 40). Average density for Inia was 0.2 ± 1.2 ind km−2 with overall abundance estimated at 3 individuals (95% CI: 0 to 8). Visual surveys observed more Sotalia individuals during earlier hours of the day and during the dry season. Preliminary acoustic surveys undertaken with C-POD passive acoustic monitoring devices indicated a diel pattern in detections of cetacean vocalization with more diurnal activity and with detections ceasing from midnight until 10:00 AM. This work highlights the possibility of monitoring both river dolphin species through visual and acoustic surveys to generate baseline information on abundance trends and distribution patterns in the Ucayali region, an area with high levels of human disturbance. <![CDATA[Antioxidant activity and apparent digestibility of amino acids of three macroalgae meals in the diets of Pacific white shrimp (<em>Litopenaeus vannamei</em>)]]> ABSTRACT The antioxidant activity of meals, growth performance, dry matter, crude protein and amino acid apparent digestibility coefficients (ADC) were determined for three macroalgae in Pacific white shrimp juveniles: Gracilaria vermiculophylla, Dictyota dichotoma and Ulva lactuca. For the digestibility determination, test diets included 15% of the test ingredients and 85% of a control diet supplemented with 1% chromic oxide. The amino acid content in the ingredients, diets and feces were analyzed using HPLC. In general, nutrient digestibility values were far higher in the diets with macroalgae meals than in the control diet. In conclusion, diets with the macroalgae U. lactuca and G. vermiculophylla in particular showed high antioxidant activity, high amino acid digestibility and improved Litopenaeus vannamei growth. <![CDATA[Assessment of some nongenetic factors that affect egg mass weight of channel catfish, <em>Ictalurus punctatus</em>]]> Abstract Channel catfish, Ictalurus punctatus, is one of the most important fish species for aquaculture worldwide. Egg mass production is directly related to the success and profitability of hatchery farms assuring an adequate egg and consequently fry and fingerling quantity. Most of the success of hatchery farms in Mexico rely on the capacity of production for enough fry to cover the demand of grow-out farms. An analysis was performed with the purpose of estimate the effect of year, month, color, pond and water temperature on egg mass weight data (EMW, g) (n = 3201). The overall mean for EMW was 683.21 g. The effect of all assessed factors was highly significant (P &lt; 0.0001). Pond and year effects suggested an effect possibly related to management strategies. Month indicated an important effect on early spawning, and water temperature showed a highly significant effect of gradient pattern on EMW (P &lt; 0.0001), with a linear slope of −67.8 g by increasing temperature degree. Results confirmed the importance of non-genetic influence on egg mass production, supporting the need for attention of this highly variable trait and suggested the possible improvement on this reproductive indicator through the better control of environmental sources of variation. <![CDATA[Growth, elemental and proximate biochemical composition of larval Amazon River prawn, <em>Macrobrachium amazonicum</em>, reared under different salinity conditions]]> Abstract In the aquaculture of prawns in inland facilities, the supply with natural seawater is technically difficult and expensive, while the use of artificial salt may be suboptimal due to unfavorable ionic composition. In the present study, Amazon River prawn, Macrobrachium amazonicum, were reared from hatching through nine larval stages to the first juvenile instar, comparing four experimental conditions with two salinities (5, 10) and two different types of salt (artificial, natural). Larval biomass growth was measured in terms of changes in dry weight (W), contents of carbon and nitrogen (C, N), and proximate biochemical composition (lipid, protein); moreover, body size (carapace length, CL) was measured in first-stage juveniles. After passing through the non-feeding first larval stage, later stages showed an exponential increase in values of biomass per individual. Rates of increase differed significantly among treatments, showing generally lower growth in experiments with artificial vs. natural salt, and at 5 vs. 10. The same response pattern was found also in CL of early juvenile shrimps. Similar but mostly weaker effects were observed in the percentage C, N, lipid, and protein values (in % of W), and in the C: N mass ratio. Our data indicate that larval rearing of M. amazonicum is feasible with artificial salts and at lower than commonly used standard salinity (10). This makes the cultivation of this species feasible also in aquaculture facilities located at large distance from the coast, where a reduction of costs and logistic investments may compensate for reduced larval growth and production of smaller juveniles. However, these salinity effects on offspring production have to be taken into account in comparisons of growth data from different laboratories and locations. <![CDATA[Metazoan parasites of freshwater ornamental fishes]]> ABSTRACT This study aimed to characterize the metazoan parasitic fauna associated with freshwater farmed ornamental fish in Southern Brazil. Between July 2014 and January 2015, a total of 423 fish belonging to nine species were examined: Pterophylum scalare, Betta splendens, two varieties of Carassius auratus, Danio rerio, Xiphophorus helleri, two varieties of Xiphophorus maculatus, Poecilia sphenops, Tanichthys albonubes and Puntius sachsii. In each fish collection, the water quality parameters were measured. Specimens were obtained from three ornamental fish farms located in three micro-regions in the State of Santa Catarina (Araquari, Biguaçu and Camboriú). Parasitological indexes were obtained after qualitative and quantitative parasitological analysis. Monogenean parasites, nematodes, and cestodes were found in all facilities. Nevertheless, nematodes and monogeneans presented 100% of prevalence in P. scalare from Araquari. From the analyzed species, P. scalare showed the highest parasite richness. <![CDATA[Diatom blooms and primary production in a channel ecosystem of central Patagonia]]> Abstract Here we report on the seasonal productivity cycle at a fixed station in the Puyuhuapi Channel (44°S, 73°W), Chilean Patagonia. The analysis of in situ water column data and longer-term records of satellite-derived surface ocean color (Chl-a) highlighted two contrasting seasons. A more productive period occurred between August and April, where depth-integrated gross primary production (GPP) estimates ranged from 0.1 to 2.9 g C m−2 d−1, and a shorter, less-productive season lasted from May to July with GPP ranging from 0.03 to 0.3 g C m−2 d−1. Diatoms of the genera Pseudo-nitzschia, Skeletonema and Chaetoceros dominated the phytoplankton, and showed a pronounced seasonality greatly influenced by prevailing environmental conditions. Warmer waters were associated with high concentrations of Pseudo-nitzschia spp., while high abundances of Skeletonema spp. and Chaetoceros spp. were associated with fresher silicate-rich waters. A marked Skeletonema spp. bloom characterized the onset of the productive season in August 2008, and with some exceptions, the highest levels of GPP (1.5 to 2.9 g C m−2 d−1) were measured when Skeletonema dominated the phytoplankton community. Reduced production (low GPP) was observed during periods of increased discharge from the Cisnes River, whereas the “spring” diatom bloom (or late winter bloom in Puyuhuapi Channel) observed during August 2008 coincided with a ~50% drop in the freshwater discharge. We therefore suggest that periods of intensive freshwater Input, that increase the silicic acid concentrations in the upper layers, provide ideal growing conditions for diatoms as the freshwater flow subsequently recedes. Principal component analysis (PCA) suggests that a decrease in salinity, increase in silicic acid concentration, and growth of Skeletonema spp. and Chaetoceros spp., are probably key factors in the annual cycle of GPP in Puyuhuapi Channel. <![CDATA[Proposal of ecological flow at Ayuquila-Armeria River watershed in western Mexico]]> RESUMEN En los últimos 100 años los ríos han experimentado grandes modificaciones. En México se han tomado medidas para resarcir los daños causados a través de la Norma Mexicana NMX-AA-159-SCFI-2012, que establece el procedimiento para la determinación del caudal ecológico. La cuenca del Río Ayuquila-Armería, uno de los más importantes ríos del occidente de México, ha sufrido en los últimos años el desecamiento a su salida al mar, lo que ha representado un obstáculo para las especies migratorias. El objetivo de este estudio es la propuesta de caudal ecológico de distribución mensual, utilizando los métodos hidrológicos, combinados con la utilización del método de hidrobiológico, definidos en la norma mexicana. Como resultado de los métodos hidrológicos suma un volumen total de 1.088 hm3 año1, el método hidrobiológico estima un caudal mínimo ecológico de 4,5 m3 s-1, indicando que en niveles de gasto por debajo de este caudal las “especie objetivo” no podrían sobrevivir debido al descenso del hábitat potencial útil. El resultado final es un régimen mensual de caudales, para la época de estiaje (noviembre-mayo) con un 7% de reserva de agua, y para los meses más secos de marzo a mayo con 2%, con caudales de 5 m3 s-1 en marzo, 4,5 m3 s-1 para abril y 4,4 m3 s-1 en mayo, asegurando la protección de la fauna acuática, en lluvias de junio a octubre con una reserva de agua de 41%, alcanzando su caudal más elevado en septiembre con 105,3 m3 s-1 mejorando la dinámica hidrológica y geomorfológica del río.<hr/>ABSTRACT Rivers have experienced great changes in the last 100 years. In Mexico, measures have been taken to compensate for the damages caused, through the Mexican Standard NMX-AA-159-SCFI-2012, which establishes the procedure for determining the ecological flow. The watershed of the Ayuquila-Armeria River, one of the most important rivers in western Mexico, has suffered in recent years drying out, towards to the sea, which has been an obstacle for migratory species. The objective of our study is the proposal of ecological flow of monthly distribution, using the hydrological methods, combined with the use of the hydrobiological method, defined in the Mexican standard. As a result of hydrological methods totaling 1.088 hm3 year1, the hydrobiological method estimates an ecological minimum flow of 4.5 m3 s-1, indicating that in spending levels below this flow the “target species” would not survive if flows fall below these levels due to significant decreases in their Weighted Usable Area (WUA). The final result is a monthly flow regime; during the dry season (November-May) it maintains a 7% water reserve, and for the driest months from March to May, 2%, with flow rates of 5 m3 s-1 in March, 4.5 m3 s-1 for April and 4.4 m3 s-1 in May, the protection of aquatic fauna was ensured, in rainfall from June to October it has a water reserve of 41%, reaching its highest flow in September with 105.3 m3 s-1 improving the hydrological and geomorphological dynamics of the river. <![CDATA[Effect of bacterial probiotics bio-encapsulated into <em>Artemia franciscana</em> on weight and length of the shortfin silverside (<em>Chirostoma humboldtianum</em>), and PCR-DGGE characterization of its intestinal bacterial community]]> ABSTRACT The shortfin silverside (Chirostoma humboldtianum) is a native fish of central Mexico with high value for artisanal fisheries. So far, attempts aimed to establish intensive culturing have failed. In this study, we evaluated the effect of probiotic strains; Bifidobacterium animalis subsp. lactis BB-12, Lactobacillus johnsonii C4, and Bacillus sp. B2 bio-encapsulated into Artemia franciscana on Chirostoma humboldtianum weight and length. Their influence on the fish intestinal bacterial communities was also assessed. The final weight and final length of the fishes fed with bio-encapsulated Bifidobacterium animalis BB-12, and L. johnsonii C4 were statistically different and higher than the control group. According to PCR-DGGE fingerprints of 16S rRNA gene, the intestinal content bacterial community associated with the shortfin silverside seems to be molded in early larval stages and only slight changes could be induced by the use of bio-encapsulated bacterial. An increase in fish survival rate and an improvement in weight and length were detected using L. johnsonii C4 bio-encapsulated into A. franciscana, in spite of its small impact on the structure of the bacterial community associated with the intestinal content of shortfin silverside. The use of L. johnsonii C4 bio-encapsulated into A. franciscana could be an excellent option to improve the yield during intensive culturing of the shortfin silverside. <![CDATA[Replacement of soybean meal by peanut meal in diets for juvenile Nile tilapia, <em>Oreochromis niloticus</em>]]> ABSTRACT The use of alternative feeds aims to maintain productivity and reduce animal production costs. This objective of this study was to determine the nutritional value of peanut meal (PNM), as well as replacement of soybean meal (SBM) by PNM in diets for Nile tilapia, Oreochromis niloticus. To determine the apparent digestibility coefficients (ADC) of nutrients from the PNM, 40 fish (100 ± 4.3 g) were randomly distributed in four 250 L tanks and fed reference and test diets (50% PNM) plus 0.1% chromic oxide. Feces were collected by modified Guelph system. For the growth performance trial, 180 fish (13.4 ± 0.2 g) were randomly distributed in 30 200 L tanks and fed during 90 days with isoproteic (26.8% digestible protein) and isoenergetic (17.6 kJ g-1 digestible energy) diets containing replacement levels of 0, 25, 50, 75 and 100% of SBM digestible protein by PNM digestible protein. The experimental design was completely randomized with five treatments and six replicates. The ADC for protein from PNM was 90.9% whereas the ADCs for essential amino acids ranged from 88.7% for lysine to 97.6% for arginine. The feed conversion ratio was significantly affected when the SBM was totally replaced by PNM. The protein efficiency ratio, protein retention and whole-body protein content significantly decreased in fish fed diets containing PNM levels above 25% of PNM. Therefore, PNM can replace up to 25% of SBM without impairing juvenile Nile tilapia growth performance, feed efficiency, and body composition. <![CDATA[The combined effects of salinity and temperature on the proximate composition and energetic value of spotted rose snapper <em>Lutjanus guttatus</em> (Steindachner, 1869)]]> ABSTRACT Combined effects of temperature (25, 30 and 35°C) and salinity (15, 25, 35 and 45 g L-1), on the body composition and energetic value in the juvenile spotted rose snapper (Lutjanus guttatus), were investigated over 90 days. Significant effects of temperature, salinity, and their interaction on body composition and energetic value were analyzed. Low temperatures (25°C) significantly reduced the protein and increase lipid content in the body. In a temperature of 30°C, the highest energetic value was recorded, and in the highest salinity (45 g L-1), the energetic value was reduced. The salinity of 15 has the highest growth, protein content, and energetic value. It was found that the optimal temperature-salinity combination for the best relationship of growth (3.8% d-1), protein (21.9%), and lipid (4.9%) content, and energetic value (2.61 kJ g-1) was at 30 to 32.0°C and salinity of 35 g L-1. The effect of temperature was directly proportional to the increase in protein and inversely with the content of lipids in the body; salinity has its main effect negatively on these parameters in the highest salinity (45 g L-1). <![CDATA[Occurrence of a juvenile white shark (<em>Carcharodon carcharias</em>) in the southeastern Gulf of California, Mexico]]> ABSTRACT Records of white sharks (Carcharodon carcharias) sightings or captures from the southern Gulf of California have been poorly documented and anecdotal evidence is limited. Even rarer is the event of a juvenile in subtropical waters. In the present paper, we report the capture of a juvenile female white shark taken in the lower Gulf of California, which represents an important contribution among the connectivity between individuals from California, United States and the Gulf of California, Mexico. <![CDATA[Protocol for obtaining rainbow trout (<em>Oncorhynchus mykiss</em>) axenic fingerlings]]> RESUMEN El presente trabajo describe protocolo sobre la aplicación del desinfectante Buffodine® y un mix de antibacterianos para obtener alevines axénicos de trucha arcoíris (Oncorhynchus mykiss). Este protocolo permitió obtener y mantener alevines axénicos de trucha por un período de 26 días. Este período permite aplicaciones como ensayos con organismos gnotobióticos, una herramienta fundamental en los estudios para el entendimiento de la interacción bacteria-hospedero o parásito-hospedero.<hr/>ABSTRACT In this paper a protocol based on the application of Buffodine® disinfectant and a mix of antibacterials for obtaining rainbow trout (Oncorhynchus mykiss) axenic fingerlings is described. This allowed to obtain and maintain axenic trout fingerlings for a period of 26 days. This time allow to achieve a gnotobiotic organism, a fundamental tool in studies of the understanding bacteria-host interaction or host-parasite interaction. <![CDATA[First record of <em>Parasphaerosyllis indica</em> (Polychaetae: Syllidae) from Easter Island, Chile]]> ABSTRACT This study is the first to report the presence of the polychaete Parasphaerosyllis indicaMonro, 1937 (Syllidae) near the coastal areas of Easter Island (27°10'S, 109°20'W). This species has a circumtropical geographic distribution and low abundance and frequency rates in relation to other Syllidae species (12) collected from Easter Island. With P. indica, the benthic polychaetes biodiversity of Easter Island is now 71 species. <![CDATA[Characterizing trophic ecology of the checkered puffer (<em>Sphoeroides testudineus</em>)]]> ABSTRACT Sphoeroides testudineus (Linnaeus, 1758), is a common, widely distributed fish in coastal ecosystems. To better understand the trophic niche of S. testudineus, we collected individuals from tidal creeks on Abaco Island, The Bahamas, and employed stomach content and stable isotope analysis. Examination of stomach contents showed that mollusks, such as West Indian false cerith snails, cerith snails, and tellin clams, were the most common prey items. Diet data were consistent with stable isotopes data such that S. testudineus seem to feed at an intermediate trophic position in the food web. These preliminary data suggest that S. testudineus may be a critical intermediate link in these wetland food webs, serving as pathways through which energy is transferred from primary consumers to other predator species. <![CDATA[Advances in reproductive study of Pacific pomfret (<em>Brama</em> australis) in Chile central coast]]> RESUMEN La información sobre los rasgos reproductivos de Brama australis, es escasa o no ha sido actualizada. Mediante análisis histológico, se estudió el tipo de reproducción, la madurez en longitud y las diferentes fases de desarrollo gonadal de machos y hembras. Se analizaron ejemplares capturados en la zona costera de Chile central. Los resultados confirmaron que las hembras presentan desarrollo asincrónico de sus ovarios, característico de los desovadores parciales. El modelo ajustado, indicó que las hembras maduran a una longitud media de 37,7 cm de longitud horquilla. En el caso de los machos, los datos sugieren que estos maduran a longitudes inferiores a las hembras. Basados en la ausencia de ejemplares en actividad reproductiva reciente o inminente, en este y otros estudios, se discute la hipótesis que el proceso reproductivo de la especie se podría realizar en zonas alejadas de la costa, fuera del área de operación de la flota.<hr/>ABSTRACT Reproductive traits information about Pacific pomfret (Brama australis) is scarce or not have been updated. Through histological analysis, the type of reproduction, maturity length and different gonadal stages development in males and females were studied. Specimens from the central coast of Chile were analysed. The results confirmed that females exhibited an ovary with asynchronous development, which is a characteristic of partial spawners. The adjusted model indicated that females mature, in average at 37.7 cm of fork length. Data suggests that males mature at smaller sizes compared to females. Based on the absence of recent or imminent reproductive activity in this and other studies, the hypothesis that the reproductive process of the species takes place rather off-shore, beyond the fishing zones is discussed.