Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Small pelagic fisheries have been characterized by large fluctuations in abundance due to environmental factors, harvest regimes, and reproduction patterns, among others. Given this complexity, the development of management schemes for sardine fisheries requires an evaluation of the impact of different management strategies. The evaluation of any management scheme would need to account for the uncertainty associated with the biological behavior of resources and economic performance of the fisheries to predict changes in resource abundance through simulation of alternative scenarios. In this study, an agestructured dynamic bioeconomic model of the Pacific sardine (Sardinops sagax) fishery off the Baja California peninsula in Mexico was used. The model assessed the effect of changes in recruitment over several state variables (biomass, net present value and catch). An analysis of risk and uncertainty allowed the identification of sensitive parameters (natural mortality, price and catchability) and a precautionary approach was used to evaluate the response of decision-makers with different attitudes toward risk (adverse, neutral and prone) given different management scenarios, from open access to restrictions in fishing effort. Incorporation of uncertainty and risk analyses into the assessment of the sardine fishery showed that management strategies that involve restrictions on fishing effort resulted in a lower probability (0-7, expressed in percentage) of exceeding limit reference points (LRPs) than those strategies that permit conditions of open access, or that aim for catch at maximum sustainable yield (MSY) and catch quotas (13-60%). The analysis highlights the advantages of using an approach that incorporates risk and uncertainty for generating management strategies for pelagic fisheries with high exposure to uncertain conditions.

The study aimed to evaluate the effect of 4 levels of dietary protein (20, 30, 40 and 50%) and lipids (2, 4, 8 and 16%) on the magnitude and duration of specific dynamic action (SDA) and postprandial nitrogen excretion in the subadult white shrimp Litopenaeus vannamei using computer-controlled metabolic chambers (continuous-flow respirometer). We determined the oxygen consumption rate at 1 h intervals until the postprandial oxygen consumption rate returned to the pre-feeding level. Shrimp fed all the diets had significantly higher respiration rates after feeding due to the SDA. Oxygen consumption, the SDA coefficient and the SDA magnitude increased notably with increasing dietary protein content. Shrimp fed the 20% protein diet had the lowest levels of pre- and post-feeding respiration and the smallest SDA. A significant change in the SDA coefficient relative to each lipid level was not demonstrable. Additionally, nitrogenous excretion increased with an increase of dietary protein but not with an increase of lipid level. By estimating the SDA of subadults, the response to standard metabolic rate (SMR) was lower than that reported for juveniles and postlarva white shrimp

The presence of flagellar systems is common in several free-living bacteria; however, these have been considered absent in bacteria belonging to the Rickettsiales order. Candidatus Hepatobacter penaei is a marine Rickettsial bacterium described as a motile microorganism propelled by a flagellar system that facilitates infection. This bacterium represents a major risk of infection in shrimp farms. Therefore, the objective of this study was to determine the presence of genes encoding the flagellar system proteins of the bacterium Candidatus Hepatobacter penaei. The genomic sequence of the GenBank database with accession number NZ_JQAJ00000000.1, was analyzed. After genes were identified, amino acid sequences were deduced. The amino acid sequences of the flagellar system were identified by BLASTP through multiple alignment of conserved domains. Subsequently, a modeling process of FlhA protein was performed and compared with the protein reported for Oceanibaculum indicum considering the formation of -helixes and -sheets. Results showed the presence of some amino acid sequences of the genes related to bacterial flagellar system as MotA FliG, FliN, FliL FlhA, FlhB, FliQ FliR and FliF. Finally, these results suggest that Candidatus Hepatobacter penaei is a rickettsial bacterium having a flagellar system, which possibly confers motility and take part in the infection process in hosts such as marine crustaceans.

Microalgae are photosynthetic eukariotic microorganisms capable of producing a wide range of compounds of commercial interest, such as vitamins, antioxidants, omega-3 fatty acids, and immunostimulants like B-glucans. B-glucans are Dglucose polymers linked by B -1,3 and/or B-1,4 bonds, which can present branches of B-1,6 bonds. The most well known in microalgae are the paramylon (in euglenoids) and the chrysolaminarin (in diatoms). In the genus Nannochloropsis, (Ochrophyta), the genome and transcriptome sequencing of species has shown that they are also likely to be able to synthesize B-glucans with B-1,3 bonds with B-1,6 side branches. There are few studies about these B-glucans in those species but it is suggested that they are carbon/energy-storage molecules that replace starch and perform similarly to storage lipids such as triacylglycerol (TAG), competing for the same precursor molecules produced by the carbon fixation. The presence of B-glucans, along with characterizing them and confirming their beneficial properties for human health, could grant a high potential to the culture of Nannochloropsis with commercial purposes. These cultures have already gained great interest because of their high contents of TAG used to produce biodiesel or eicosapentanoic acid (EPA) to feed rotifers, fish or for nutraceutical purposes in humans. The objective of this review is to describe the properties of B-glucans in microalgae and the potential use of Nannochloropsis in the production of these molecules.

The reproductive biology of Macrodon ancylodon, a commercially important fish widely distributed along South America’s Atlantic coast, is described from 240 specimens collected in northeastern Brazil. Specimens ranged from 18.2 to 33.5 cm in length, exhibiting positive allometry. Total length at first sexual maturity was 21.13 cm. M. ancylodon has an asynchronous gonadal maturation and would be a batch spawner within a reproductive period. Total weight and length of females do not affect the relative fecundity values in this species. Analysis of the gonadosomatic index, condition factor and frequency of maturational stages shows that M. ancylodon was capable of reproducing throughout the year, despite the fact that spawning peaks were observed during November-December and August-September. The results are evidence that the study area is used by M. ancylodon for reproduction. The data will also be important for the development of stock management strategies.

Global demand for food increases the interest in develop of aquaculture. Significant efforts are being made in Chile to develop Seriola lalandi culture, because of the high demand of this fish meat at national and international level. However, this species poses persisting difficulties regarding larval survival. The objective of the present study was to evaluate the effects of Pseudoalteromonas sp. bacteria as a probiotic supplement on the larval culturing of S. lalandi. For this, S. lalandi larvae were fed rotifers (Brachionus rotundiformis and Brachionus plicatilis) and Artemia sp. that were previously cultured using microalgae mixed with Pseudoalteromonas sp. Rotifers and Artemia were good probiotics vectors because S. lalandi larvae fed probiotic supplement showed higher survival that the control. These findings evidence that Pseudoalteromonas sp. are good probiotic candidates for use in S. lalandi larval cultures. However, is needed more research on major scale cultivation to validate their use commercially.

The solitary sea squirt Pyura chilensis, is considered a resource of economic importance in the artisanal fisheries sector. This organism has a great capability to colonize artificial substrates, taking part in the encrusting fauna in long-line culture systems of ostreid and mussel, affecting the growth efficiency of these resources. For this reason, is necessary to know biological - reproductive aspects of P. chilensis in order to generate new information for future implementation of management plan, conservation and cultivation of this resource in the Región de Los Lagos, Chile. The purpose of this study was to investigate the reproductive cycle and settlement patterns of P. chilensis, analyzing the condition index and gonadal histology of organisms which come from a mussel farming system in Estero Huito, Calbuco (41°43’S;73°09’W) during 12 months. In addition, the settlement substrate preference of P. chilensis larvae was examined, using two artificial surfaces. The condition index (wet mass-siphonal distance) showed an increase between June and September, coinciding with low temperatures period and the spawning season (organisms in stage IV). However, recruit presence between November and June shows possible spawning events in other seasons. It was observed between 40 and 100% to gonadal stages II and/or III in the sampled organisms during the study period, which suggest a continuous gametogenesis. In addition, the larval settlement was higher in rough-dark substrate (raschel mesh) than in plastic surface. In conclusion, the study area may be recruiting throughout the year, but at different intensity levels. This information would allow planning the collectors location to attract the seasquirts recruits, generating a continuous production of P. chilensis and decreasing the infestation in others crops.

During early development stages, embryos and larvae of marine fish use amino acids (AA) as an energy source for aerobic catabolism and for maintaining osmolality of body fluids. Amino acid profile of eggs and larvae can be used to determine essential amino acid requirements (EAA). Better understanding the evolution of biochemical composition can improve nutritional needs at the start of exogenous feeding during early stages of fish larvae; high mortalities from nutritional deficiencies have been reported at this stage. The aim of this study was to determine the proximate chemical composition and AA profile of eggs, newly hatched larvae and larvae at 4 days post-hatch (DDE). Samples of previously mentioned stages were taken and the proximate composition and AA profile were determined using standard methods. The percentage of protein was significantly higher in the larvae 4 DDE lower in lipids. The amount of histidine, arginine and methionine was higher in the eggs and the rest of EAA was higher in the larvae at 4 DDE. The percentage of taurine was significantly higher in the eggs. These findings may serve as a guideline of EAA requirements for spotted rose snapper larvae at the onset of exogenous feeding and contribute to better feeding protocols and develop balanced diets to improve larval growth and survival.

The spiny lobster Panulirus pascuensis stands out among the endemic species of Easter Island, due to its cultural and economic importance. A total of 16 microsatellite loci were characterized in 18 individuals, 9 of which were polymorphic. The mean number of alleles per locus was 3.44 (2-6) and the observed heterozygosity ranged from 0.11 to 0.93. None of the loci exhibited significant linkage disequilibrium or departures from HWE. These new microsatellites will be used to obtain information about migration, population structure and genetic diversity of P. pascuensis in order to improve the future sustainable management and conservation plans.

The macrobenthic assemblages with mytilids of San Julián bay (Southern Patagonia; Argentina) were sampled in summer 2007 to know its structure; diversity and distribution; and to determine their relationship to different environmental factors. The study was conducted in 3 locations with different types of substrate and slope. Sampling at each site was performed in a transect to cover different levels of intertidal and shallow subtidal. A total of 46 species belonging mainly to molluscs (20); crustaceans (12) and polychaetes (10) were found. Three main macrofaunal assemblages were identified. Platynereis-Clunio- Darina assemblage was distributed in the upper intertidal of muddy and gentle slopes substrate; and had the lowest values of number of species; diversity and abundance of individuals. The Mytilus-Perumytilus assemblage was distributed in the middle and lower intertidal levels in rocky substrate or muddy substrate with abundant support elements and medium slope. This assemblage presented intermediate values of diversity and greater abundance of individuals. The Aulacomya-Exosphaeroma assemblage had the highest number of species and the greatest diversity; but low abundance of individuals; being related to rocky substrate or muddy substrate with support elements and low slopes in the upper subtidal. Species richness and diversity of these assemblages increases from the upper intertidal to subtidal; possibly because of a complex gradient of stress; mainly caused by desiccation and exposure to extreme temperatures.