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The present study evaluated the effects of feeding frequency during the grow‐out phase of Litopenaeus vannameiin biofloc system. The experiment comprised of four treatments with three replicates each, corresponding to the following feeding frequencies: one (8:00 a.m.), two (8:00 a.m. and 4:00 p.m.), three (8:00 a.m., 12:00 p.m. and 4:00 p.m.) and four times a day (8:00 a.m., 10:00 a.m., 12:00 p.m. and 4:00 p.m.). Zootechnical performance and digestive enzyme activity were monitored for 63 days. At the end of the experiment, the highest survival rates were found for the individuals fed three and four times a day. Wet weight gain (6.63 g) and specific growth rate (3.46% per day) of the individuals fed three times a day were significantly higher compared to animals fed one and four times a day, but did not differ significantly to the group fed twice a day (6.15 g and 3.46% per day, respectively). The digestive enzyme activities were not affected by the feeding frequency, but negative correlations were found between these activities and shrimp weight. It is recommended that L. vannamei should be fed three times a day during the grow‐out phase in a biofloc system under the conditions used in this study. [ABSTRACT FROM AUTHOR]

The present study aimed to investigate the reproductive cycle and size at first maturity of Penaeus schmitti through a macro and microscopic approach. Between August 2011 and July 2012, 1169 specimens were collected by an artisanal fishing vessel operating a double trawl off the coast of Pernambuco, northeast Brazil. The total proportion of males (42%) was significantly lower than females (58%), corresponding to the sex ratio of 1:1.38. The total body length at first ovarian maturation (TL50) in females was estimated at 14.2 cm. The ovarian development was divided into four distinct stages based on histological characteristics and visual observations. This is the first reported occurrence of vitellogenic oocytes in the spent stage of P. schmitti, indicating a rapid ovarian maturation after spawning. Furthermore, the frequency of maturation stages, diameter of oocytes and gonadosomatic index were distributed homogeneously throughout the study period, reinforce a continuous reproductive cycle for P. schmitti population in northeastern Brazil. [ABSTRACT FROM AUTHOR]

The reproductive cycle of Xiphopenaeus kroyeri north-eastern Brazil was described to contribute to the sustainable management of this stock in the region. Specimens were collected monthly from August 2011 to July 2012 using a local vessel of the artisanal fleet. A total of 1201 individuals were analyzed (673 females and 528 males) with a mean carapace length (CL) of 1.88 ± 0.16 cm and total length (TL) of 9.00 ± 1.22 cm. The lowest CL and TL of mature females were 1.33 and 6.5 cm, respectively, and all females above 2.44 cm (CL) and 11.5 cm (TL) were mature. Ovarian maturation was classified into four stages: I (immature), II (maturing), III (mature) and IV (spawned). Individuals of all maturational stages were present throughout the year. Considering the macro and microscopic analysis, it was suggested that this species in north-eastern Brazil has a continuous reproductive cycle, with two seasonal peaks, November/December and February (austral spring and summer). A positive correlation between the percentage of mature females and temperature was observed, and a higher percentage was reported in the warmer months of the year. This suggests that the reproductive peaks can be triggered by water temperature variation throughout the year. [ABSTRACT FROM AUTHOR]

Shrimp farming is a fast-expanding activity that has supported the growth in the supply of these crustaceans to consumers around the world. However, the end product is vulnerable to contamination at all stages of the process, including the rearing tanks, where current practices prioritize to raise stocking densities and the minimization of water renewal. It is thus important to evaluate the potential of these systems for the proliferation of undesirable microorganisms, which may render the product unfit for human consumption. In the present study, the presence of coagulase-positive Staphylococcus, Salmonella spp., Vibrio spp., and total and thermotolerant coliforms was verified in biofloc tank and conventional pond systems used for the rearing of Litopenaeus vannamei in Pernambuco, Brazil, and the results were compared with the legislation regulating the marketing of fresh shrimp. Samples were collected from two biofloc tanks with a density of 375 shrimp m−2, and two conventional ponds with 12 shrimp m−2. None of the samples tested positive for either Salmonella spp. or coagulase-positive Staphylococcus, which is consistent with the legislation. While no standards are defined legally for Vibrio spp. or coliforms, very low concentrations were recorded in both systems, in comparison with other studies. While some variation in bacterial contamination was observed over the rearing process, the end product of both systems was fit for human consumption. The results of the study indicate that, while the water is not renewed in the biofloc system, the development of undesirable microorganisms can be controlled, with no adverse effects for the end product. [ABSTRACT FROM AUTHOR]

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Abstract: The interest in culturing indigenous penaeid species has increased lately due to Litopenaeus vannamei disease outbreaks, especially in southern Brazil. Although sustainable production of the pink shrimp Farfantepenaeus paulensis is greatly desired, it has been constrained by the current dependency on wild-caught broodstock. To overcome this problem, research efforts have focused on the development of domesticated stocks and optimization of their reproductive performance under laboratory conditions. We present the latest developments on maturation and reproduction of this closed thelycum species, aiming to improve the future outlook for a sustainable nauplii production. [Copyright &y& Elsevier]

Abstract: The reproductive performance of similarly-sized wild-caught (W) and domesticated (D) Farfantepenaeus paulensis broodstock (mean weight of 46 g for females and 29 g for males) was assessed over 30 days under standardized conditions. Wild broodstock were collected from a population off the coast of Santa Catarina, Brazil. The domesticated shrimp were first generation lines originated from the same population as the wild broodstock and were reared to 16 months of age in covered raceway tanks. Reproductive performance (e.g. data from successive spawnings) and offspring quality (egg diameter, length and survival of nauplii and protozoea stages) were recorded. Mature ovaries were sampled for the evaluation of gonadosomatic index (GSI), histological characteristics and fatty acid content. The GSI and ovarian histology indicated that full maturation was attained by both groups, but domesticated females showed a higher percentage of mature oocytes (mean±standard deviation) (W =25.9±7.4%; D =35.5±14.2%). Spawning performance and offspring quality were similar between wild and domesticated broodstock. Although a significantly higher number of eggs per spawning event (W =184,371±89,011; D =147,426±79,348) were observed for wild females, the total number of eggs per female (W =529,065±324,412; D =421,587±257,677), egg fertilization (W =75.8±28.8%; D =69.8±27.9%) and hatching rates (W =52.3±35.0%; D =64.1±15.7%) were similar between the two broodstock sources. Ovaries of wild females contained significantly higher levels of n−3 highly unsaturated fatty acids and, as these females produced comparatively more eggs per spawning event, it suggests that these fatty acids may have a role on ovarian development and fecundity. Overall results suggest that the reproductive performance, offspring quality, and ovarian maturation of 16-month-old domesticated F. paulensis broodstock were equivalent to that of similarly-sized wild-caught broodstock from deep-sea waters. [Copyright &y& Elsevier]

The objective of this study was to identify morphological characteristics of different populations of Penaeus schmitti Burkenroad, 1936 to contribute to its biology and conservation. In order to compare geographically isolated populations, between 2014 and 2016, selected biological variables were analyzed in six populations dispersed along the Brazilian coast and one from the Cuban coast. Specimens with eight upper rostral teeth predominated. The ordination of shrimp measurements by non-metric multidimensional scaling showed the greatest dispersion on data from Cuba, Rio Grande do Norte, and Espirito Santo, which are also the localities that presented the highest coefficient of variation. On the other hand, the values corresponding to Sergipe, Rio de Janeiro, Paraná, and Santa Catarina showed a greater similarity or clustering of the data of each location. Tail weight was estimated using length and depth of the sixth abdominal segment. The populations of Santa Catarina, Brazil (28°S), had the longest and heavier abdomens proportionally among all the compared populations, while the organisms of Manzanillo, Cuba (20°N), had proportionally shorter abdomens and the narrowest cephalothorax. The regression equation indicated a positive allometric growth for P. schmitti, and the largest total length reported for genus Penaeus in the natural environment corresponded to a P. schmitti specimen. This information could be useful in future taxonomic studies to correctly identify the species and its morphological variability. Color differences were also observed, with white ventral spots in the sternite XIV of some females from Brazilian populations, which was not previously reported in the literature. Extending these studies is recommended to contribute to the conservation and culture of P. schmitti. [ABSTRACT FROM AUTHOR]

Pacific whiteleg shrimp is the topmost aquacultured species produced in the world. However, shrimp feeding behavior results in unnecessary expenditures, as some of the feed offered is not entirely consumed. Nowadays, aquaculture has become more accepting of using animal by-products such as poultry meal as a protein source to replace fishmeal. Unfortunately, such by-products might affect shrimp acceptance of the offered feed. The present work evaluates the use of a chemosensory feed effector with attractive properties on the feeding behavior, growth performance, and salinity stress tolerance in juvenile Litopenaeus vannamei. Nine diets were formulated to contain either poultry meal (6%), or fishmeal (6% or 12%) as animal protein source, with feed effector supplemented at 0, 0.1, and 0.2%. The various diets were offered to naïve and non-naïve shrimp to evaluate feed consumption. Concurrently, shrimp feeding behavior was monitored using passive acoustic monitoring. Afterwards, a 42-days growth trial was performed followed by a salinity stress trial were performed to evaluate the effect of the feed effector in shrimp diets on animal growth, survival, and stress tolerance. Results of the present study indicate significant positive relationships between the number of clicks and feed consumed after 30 min (p < 0.001, r = 0.46 to 0.69). Additionally, shrimp offered the poultry meal-based diets produced significantly more "clicks" when the diets were supplemented with the feed effector, compared with the rest of the diets. However, the shrimp consumed poultry meal-based diets similarly to the fishmeal-based diets, only when supplemented with the feed effector. Interestingly, no significant differences were observed in terms of final biomass, final average individual weight, weight gain, FCR, or survival. However, salinity stress trial results indicate significantly better survival when offered diets supplemented with the feed effector, regardless of the level of inclusion. Results of the present work suggest that supplementing the feed effector to shrimp diets improves palatability and shrimp acceptance of diets formulated with poultry meal as sole animal protein source, as well as improves shrimp tolerance to salinity fluctuations. In an era of limited resources, supplementation of poultry meal-based shrimp diets with feed effector improves overall profitability by obtaining good shrimp growth with less expensive diets, and despite of stressors. • Feed effectors can improve shrimp acceptance to feed formulated with animal by-products proteins to replace fishmeal. • Passive acoustic monitoring is useful to assess shrimp feeding on animal by-products based feed, with feed effectors added. • Feed effectors have the potential to improve shrimp tolerance to salinity stress. • The feed effector positively influenced the number of clicks emitted by the shrimp when feeding. • Despite not influencing growth or survival, shrimp tolerance to salinity stress improved with feed effector addition. [ABSTRACT FROM AUTHOR]

Penaeid shrimp emit click sounds during feeding activity generated by the collision of mandibles. These sounds have been used as a basis for research of feeding behavior and acoustic-based automatic feeders in shrimp farming. However, the use of automatic feeders is generally recommended for shrimp larger than 2 g or more. The aim of the present study was to evaluate the click acoustic parameters during feeding activity of Penaeus vannamei from post-larvae up to 12 g in laboratory. Twelve progressive weight classes (0.01 to 12 g) along nursery and grow-out phases were recorded in tanks internally covered with an acoustic foam. Recordings were carried out using an omnidirectional SoundTrap 300 STD hydrophone (sampling rate: 288 kHz; 16 bits). At the end of the recordings, shrimp were measured (body weight and cephalothorax length) and had their mandibles dissected for length measurements. The clicks emitted by shrimp during acoustic recordings were automatically detect using Raven® software, and 100 clicks per weight class were randomly selected for acoustic sound characterization (low, high and peak frequency, maximum power and duration time). The clicks start to be emitted by P. vannamei at the average weight of 0.01 g, with a band frequency between 15.4 and 70.5 kHz and low maximum power (23.2 dB). The low and peak frequency showed an abrupt decrease until shrimp reached 1.16 g, while maximum power and high frequency presented an opposite pattern. The click sound duration time did not show a clear variation among the different weight classes evaluated. Acoustic parameters showed a significant linear relationship with mandible length, indicating a direct influence of this structure on sound emission. The regression derivative analysis estimated that click maximum power stabilized from 1.48 g onwards, while low, high and peak frequency stabilized from 3.08 g shrimp onwards. The results suggest that it would be possible to anticipate and optimize the use of acoustic-based automatic feeders in P. vannamei farming. • Click emission during feeding activity is first reported for post-larvae of Penaeus vannamei. • The mandible length was correlated with the click acoustic parameters. • The acoustic parameters values stabilized around 1.5 and 3.0 g. • Results indicate the possibility to anticipate and optimize the use of acoustic-based automatic feeders in shrimp farming. [ABSTRACT FROM AUTHOR]

Histological and histochemical changes during oocyte development were evaluated in order to establish a model for better understanding nutrient dynamics throughout vitellogenesis and overall penaeid reproduction. Samples of Xiphopenaeus kroyeri females (n = 587) at different stages of gonadal maturation were subjected to histological and histochemical analysis for the identification of neutral polysaccharides, total proteins, and tissue differentiation. We observed that the ovarian structure was composed of collagen fibers and oviducts were lined by three layers of epithelium separated by muscular tissue. Oogenesis was classified into six distinct phases: chromatin nucleolar oocytes, chromatin perinucleolar oocytes, oocytes in primary vitellogenesis, oocytes in secondary vitellogenesis, mature oocytes, and atretic oocytes. Histochemical observations suggested that during the previtellogenesis phase, proteins and neutral polysaccharides were not present. However, a progressive increase in these substances occurred from vitellogenic oocytes until their final maturation stage. Follicular cells composed the follicular complex forming an external epithelium in vitellogenic oocytes, and are probably involved in protein transfer during maturation process. Collagen and glycoprotein vesicles were identified in the cytoplasm of mature oocytes of X. kroyeri. Taken together, the present findings contribute to the current knowledge on the ovarian morphology and maturation process of penaeids, supporting future studies on reproductive biology and breeding performance in captivity. • Penaeid oogenesis was classified, for the first time, into six stages based on histological analysis. • An increase in proteins, neutral polysaccharides, and collagen stated from vitellogenic oocytes until their final maturation. • Instead of cortical crypts, vesicles composed of collagen and glycoproteins were identified in the final oocyte maturation. • External layer of follicular cells around vitellogenic oocytes may be involved in transferring proteins into germ cells. • Histological and histochemical approach improved our knowledge on nutrient incorporation during vitellogenesis in penaeids. [ABSTRACT FROM AUTHOR]

The study was carried out to screen the mesophilic fungal population in the pond soil of Macrobrachium rosenbergii culture in India. Soil samples were collected from April to September in two independent ponds (A and B) and fungal diversity was identified and enumerated throughout by serial dilution and colonies were subcultured using Potato Dextrose Agar (PDA) mycological methods. Physicochemical parameters were determined during the culture period and prawn productivity was measured. Twelve species of fungus were studied in the ponds and six isolates were common to ponds A and B. Nevertheless, the array of fungal species was higher in pond B whereas the number of colonies forming units was higher in pond A. The genus Aspergillus was dominant but other filamentous and yeast fungal species were also found in both ponds. Mesophilic fungal populations were most highly correlated with temperature, followed by dissolved oxygen concentration in the freshwater. Taken together, our data support that a high density of a few fungi species could be more significant for biotransformation and prawn productivity than fungal diversity itself. Thus, the effective knowledge and management of the fungal community in the pond soil could improve the productivity of M. rosenbergii culture. • The mesophilic fungal population in the pond soil was determined. • Fungal diversity was identified and enumerated via. Microbiological methods. • Twelve species of fungus were identified in the prawn culture ponds A, and B. [ABSTRACT FROM AUTHOR]