Quality Characteristics of High Pressure-Induced Hake (Merluccius capensis) Protein Gels with and without MTGase

The effects of microbial transglutaminase (MTGase; 0.5%, w/w) and high hydrostatic pressure (HHP) on the quality of protein gels from unwashed mince of hake (Merluccius capensis) trimmings were studied. MTGase incorporation improved texture. Protein solubility was lower for those gels containing MTGase, as a result of myosin heavy chain cross-linking. HHP improved texture. Pressure level was the most important HHP parameter, since higher levels (300 vs. 100 MPa) augmented gel strength (GS). A positive synergistic effect of MTGase and HHP was found for some properties, such as GS, yielding improved gels from a raw material that otherwise shows poor gelation.     

Development of Quality Index Method Scheme for Common Carp (Cyprinus carpio) Stored in Ice: Shelf-Life Assessment by Physicochemical,Microbiological, and Sensory Quality Indices

ABSTRACT

Sensory methods are the most interesting methods to estimate fish quality. Among these, the recently developed quality index method (QIM) has gained popularity, as shown by the multiple publications of QIM schemes in the last years. The objective of this study was to create a new QIM scheme (QIM sensory table and corresponding point system) for the common carp (Cyprinus carpio), basing the definition of the rejection point on sensory, physicochemical (thiobarbituric acid reactive substances, total volatile basic nitrogen, pH, and color measurements), and microbiological criteria (counts of mesophiles, psychrotrophs, and Pseudomonas spp.). A new QIM scheme was developed and is proposed for use in the future; it will be useful for practical evaluations of carp freshness in all steps of the production chain, and it will contribute to a more effective use of the species as an alternative for human food supply.     

Reproductive success of the Argentine anchovy,Engraulis anchoita,in relation to environmental variability at a mid‐shelf front (Southwestern Atlantic Ocean)

The mid‐shelf front (MSF) of the Buenos Aires province continental shelf in the Southwestern Atlantic Ocean plays a central role in the pelagic ecosystem of the region acting as the main spring reproductive area for the northern population of the Argentine anchovy Engraulis anchoita and supporting high concentrations of chlorophyll as well as zooplankton, the main food of anchovy. To investigate the influence of environmental variability on the reproductive success of E. anchoita, we analyzed a 13‐yr time series (1997–2009) of environmental data at MSF including chlorophyll dynamics, as well as zooplankton composition and abundance, ichthyoplankton distributions, and recruitment of E. anchoita. Spring chlorophyll concentrations showed high interannual variability and were mainly influenced by changes in water temperature and vertical stratification, which in turn control nutrient supply to the surface. Chlorophyll dynamics (magnitude, timing, and duration of the spring bloom) explained most of the variability observed in E. anchoita recruitment, most likely via fluctuations in the availability of adequate food for the larvae. Our results suggest that satellite ocean color products can be valuable tools for understanding variability in ecosystem dynamics and its effects on the recruitment of fish.     

Reproductive performance in female strains of Nile tilapia, Oreochromis niloticus

The Nile tilapia is among the most cultivated tropical fish in the world, yet little is known about the variations in reproductive characteristics among different strains. There is an interest in evaluating the reproductive performance of females of three tilapia strains. All strains were represented in equal proportion (n = 225), being named as Supreme (SUP), Premium Aquabel (PA), and Chitralada (CHI). These fish were cultivated for 7 weeks in the Aquabel Pisciculture Station (Brazil), from January to March 2011. The PA was the largest strain, with the highest values in all the morphometric parameters we analyzed (weight, total length, standard length and body depth). Among the evaluated reproductive parameters, the PA strain differed significantly from the other two in number and weight of eggs/female, volume of eggs/spawn and number of eggs/kg of fish. The percentage of non-spawning females in the SUP and CHI strains differed significantly from one another, while results for PA showed intermediate values and no significance compared to the other strains (P > 0.05). Among the reproductive parameters analyzed, the percentage of spawned females/week, more than one spawns during 7 weeks, and hatching rate showed no significant differences between strains (P > 0.05). There was a significant correlation (r = 0.69) between water temperature and percentage of spawned females/week. When evaluating the interval between two consecutive spawns, we observed that periods of 21 days were the most frequent in all strains. In conclusion, the strain that showed the best results in all morphometric and in most reproductive parameters we evaluated was the PA.     

A bioeconomic model for red tilapia culture on the coast of Ecuador

This study builds a long-term bioeconomic model for multi-generational tilapia farming in the coastal region of Ecuador, where associative semi-intensive tilapia culture projects have been implemented. Survival, weight and length curves were calibrated, and feed consumption and feed conversion rate curves were constructed. Revenues, costs and investments were also estimated. It was found that operational net present values per batch are maximized when fishes are harvested on approximately day 300 after stocking, in contrast to 180 days, which is the actual time of harvest at present. Thus, culture performance can be improved significantly if recommendations arising from the model are followed. Finally, sensitivity analysis of the model demonstrated that tilapia cultures can withstand unfavorable variations in critical parameters.     

Hymenopteran Parasitoids on Fruit-infesting Tephritidae (Diptera) in Latin America and the Southern United States: Diversity, Distribution, Taxonomic Status and their use in Fruit Fly Biological Control

We first discuss the diversity of fruit fly (Diptera: Tephritidae) parasitoids (Hymenoptera) of the Neotropics. Even though the emphasis is on Anastrepha parasitoids, we also review all the information available on parasitoids attacking flies in the genera Ceratitis, Rhagoletis, Rhagoletotrypeta, Toxotrypana and Zonosemata. We center our analysis in parasitoid guilds, parasitoid assemblage size and fly host profiles. We also discuss distribution patterns and the taxonomic status of all known Anastrepha parasitoids. We follow by providing a historical overview of biological control of pestiferous tephritids in Latin American and Florida (U.S.A.) and by analyzing the success or failure of classical and augmentative biological control programs implemented to date in these regions. We also discuss the lack of success of introductions of exotic fruit fly parasitoids in various Latin American countries. We finish by discussing the most pressing needs related to fruit fly biological control (classical, augmentative, and conservation modalities) in areas of the Neotropics where fruit fly populations severely restrict the development of commercial fruit growing. We also address the need for much more intensive research on the bioecology of native fruit fly parasitoids.     

Neotropical freshwater fishes imperilled by unsustainable policies

Neotropical freshwater fishes are the most diverse on the planet (>5,500 species), although nations in Latin America have been negligent regarding their conservation. National policies have historically encouraged unsustainable practices, and recent decades have witnessed a sharp increase in harmful activities. Our aim with this review was to expose this situation and illustrate how national policies constitute the main threat to freshwater fish biodiversity. We explain that the most devastating, pervasive and systemic threats are rooted in official policies, particularly unsustainable activities (e.g. hydropower, water diversion, mining, aquaculture, agriculture and fishing), poor management/conservation (e.g. fish stocking and passages) and harmful legislation (e.g. poor licensing, non‐native species). We provide a broad portrait of the Neotropical scenario, where unsustainable policies have caused considerable damage to freshwater ecosystems, and focus on major examples from Brazil, where development projects have caused large‐scale losses to fish biodiversity. Such modus operandi of human development is incompatible with the persistence of biodiversity, and no simple solution is available to correct or minimize its effects. The current situation demands a profound behavioural shift towards better practices and policies, or these multiple high‐impact activities will continue eroding freshwater fish biodiversity and impairing essential ecosystem services.