Abstract. An experiment was conducted to evaluate the effect of various levels of protein and dietary lipids on white snook (Centropomus viridis) performance. A 4 × 2 factorial design was used with 4 protein levels (40%, 46%, 52%, and 58%) and 2 lipid levels (10% and 13%), with 3 replicates per treatment. Fish with an initial weight of 14.80 ± 0.80 g were fed to apparent satiety 3 times a day for 6 weeks. Juvenile growth showed no significant differences among treatments. Feed efficiency was only affected by the protein level in the diet, and the best feed efficiency ratio was obtained with the 52% protein diets; the protein efficiency ratio was significantly lower with the 58% protein diets. The hepatosomatic index decreased with increasing protein content, and the peritoneal fat index increased with dietary lipid level. The condition factor was not affected by the dietary protein or lipid level. Hematocrit and total plasma protein were significantly higher at 40% protein; blood glucose and triglycerides were affected by both nutrients. It is concluded that juvenile C. viridis can be fed diets containing 40% protein and 10% lipids and a protein/energy ratio of 20.69 mg·kJ-1, under the experimental conditions of this study.

Resumen. Se llevó a cabo un experimento para evaluar el efecto de varios niveles de proteína y lípidos dietéticos en el rendimiento de juveniles de robalo blanco (Centropomus viridis). Se realizó un diseño factorial 4 × 2 con 4 niveles de proteína (40%, 46%, 52% y 58%) y 2 niveles de lípidos (10% y 13%), con 3 replicados por tratamiento. Los peces con un peso inicial de 14.80 ± 0.80 g se alimentaron a saciedad aparente 3 veces al día durante 6 semanas. El crecimiento de los juveniles no presentó diferencias significativas entre los tratamientos. La eficiencia alimenticia solo fue afectada por el nivel de proteína en la dieta, y la mejor tasa de eficiencia alimenticia se obtuvo con las dietas con 52% de proteína; el índice de eficiencia proteica fue significativamente menor con las dietas con 58% de proteína. El índice hepatosomático disminuyó al aumentar el contenido de proteína, y el índice de grasa peritoneal aumentó con el nivel de lípidos en la dieta. El factor de condición no fue afectado por el nivel de proteína o lípidos dietéticos. El hematocrito y la proteína total del plasma fueron significativamente mayores con las dietas con 40% de proteína; la glucosa y los triglicéridos en la sangre fueron afectados por ambos nutrientes. Se concluye que los juveniles de C. viridis pueden ser alimentados con dietas que contengan 40% de proteína y 10% de lípidos y una relación proteína/energía de 20.69 mg·kJ-1, bajo las condiciones experimentales de este estudio.

Abstract: Aim We investigate the length-weight relationship estimates of seventeen species caught using an artisanal purse seine in the Abrolhos Bank, a tropical estuarine complex in eastern Brazil. Methods From February 2012 to November 2013, fish were collected monthly using an artisanal small purse seine with a total of 84 fish landings. The fish were captured in mangrove margins during high tide and retrieved after six hours at depths ranging from 1.2 to 3 meters. Results A total of 4433 fish specimens from 17 species and nine families were sampled. The coefficient of determination ranged from 0.904 for Centropomus parallelus to 0.987 for Lutjanus cyanopterus. Species presented allometric growing, with Caranx latus, Lutjanus cyanopterus and M. curema exhibing negative allometric while all the other species presented positive allometric growing. We present first data in Brazil to L. cyanopterus and first data in the literature to Lutjanus alexandrei. Conclusions Our results provide novel data of biological attributes for 17 species. By understanding the length-weight relationships and growth patterns of these species, data at stock level may subside proper management initiatives such as fishing restrictions in fishing sites or seasons and mesh size limits.

Resumo: Objetivo Investigamos as estimativas da relação peso-comprimento de dezessete espécies capturadas utilizando uma rede de cerco artesanal no Banco dos Abrolhos, um complexo estuarino tropical no leste do Brasil. Métodos De fevereiro de 2012 a novembro de 2013, peixes foram coletados mensalmente utilizando uma rede de cerco artesanal de pequeno porte, totalizando 84 desembarques de peixes. Os peixes foram capturados nas margens de manguezais durante a maré alta e despescados após seis horas a profundidades variando de 1,2 a 3 metros. Resultados Um total de 4433 espécimes de peixes de 17 espécies e nove famílias foram amostrados. O coeficiente de determinação variou de 0,904 para Centropomus parallelus a 0,987 para Lutjanus cyanopterus. As espécies apresentaram crescimento alométrico, com Caranx latus, Lutjanus cyanopterus e M. curema exibindo crescimento alométrico negativo, enquanto todas as outras espécies apresentaram crescimento alométrico positivo. Apresentamos os primeiros dados no Brasil para L. cyanopterus e os primeiros dados na literatura para Lutjanus alexandrei. Conclusões Nossos resultados fornecem novos dados sobre atributos biológicos de 17 espécies. Ao compreender as relações peso-comprimento e padrões de crescimento dessas espécies, os dados em nível de estoque podem subsidiar iniciativas adequadas de manejo, como restrições de pesca em áreas ou épocas específicas e limites de tamanho de malha.

Abstract The assessment of water quality using multiple abiotic and biological indicators is very important for understanding anthropogenic impacts and the health of the ecosystem. The Olaria is a short river system that flows into the Cananeia estuary. This aquatic system crosses the urban center of the city of Cananeia, where it eventually receives untreated domestic wastewater. This study aims to apply multi-indicators of environmental pollution to understand the influence of the Olaria system on the Cananeia estuary. For this purpose, indicators of water quality and genotoxic and pathological responses in fish were used. Data on salinity, pH, and silicates in surface water indicate a more accentuated continental influence in the inner part of the Olaria river system. Moreover, the data recorded on the inner area of the Olaria system, which presents lower hydrodynamic characteristics and the largest urban population, indicated the presence of dissolved oxygen and nutrients (phosphate [P-PO4 -3], nitrite [N-NO2-], and ammonium [N-NH4+]) at levels that exceed the established limits for water quality by the Brazilian environmental legislation (Conselho Nacional do Meio Ambiente - CONAMA). The presence of Escherichia coli in all analyzed water samples indicates a local or point source of domestic wastewater contamination near the Olaria system. Fish species such as Centropomus undecimalis (Robalo Flexa) and Sphoeroides testudineus (Baiacu Pintado) showed toxicogenetic damage, indicating clastogenic and/or aneugenic exposure in the aquatic environment. Hepatic pathologies such as pyknosis nuclei, inflammation, hepatocyte swelling, and necrosis were found in all specimens evaluated, and C. undecimallis exhibited all these pathological changes. These results highlight the importance of biomonitoring the effects of anthropogenic disturbance on the aquatic biota that frequent the Olaria system and are dependent on the water quality.

Resumo Objetivo O objetivo foi descrever os parâmetros LWR das espécies nativas e não nativas do rio Guaraguaçu e comparar esses parâmetros das espécies não nativas obtidos no rio Guaraguaçu com os parâmetros de LWR dos seus locais de distribuição nativa disponível na literatura. Métodos Os exemplares foram coletados semestralmente entre 2004 e 2007, usando diferentes técnicas de amostragens. Resultados No total, foram analisados 673 exemplares de 10 espécies. Seis espécies apresentaram alometria positiva (b>3) e três alometria negativa (b<3) e isometria (b=3). Espécies nativas possuem parâmetros de LWR idênticos a estudos prévios, exceto Centropomus parallelus, a qual apresentou isometria neste estudo. As espécies não nativas Clarias gariepinus e Ictalurus punctatus demonstraram diferenças significativas entre os parâmetros de LWR do Guaraguaçu e das suas áreas de distribuição nativa. Oreochromis niloticus não apresentou diferença significativa entre os parâmetros de LWR entre o Guaraguaçu e sua área nativa de distribuição. Conclusões O resultado indica que as condições ambientais talvez não influenciem o crescimento das espécies não nativas, o que explicaria o sucesso de invasão destas espécies.

Abstract Aim The objective was to describe the LWR of fish species of the Guaraguaçu River, as well as to compare the LWR parameters of the non-native species with the parameters obtained in their native ranges, available in the literature. Methods In this study, the LWR of 10 fish species of the Guaraguaçu River, southern Brazil, were analyzed. Fish were sampled semiannually between 2004 and 2007, using different sampling techniques in the Guaraguaçu River. Results A total of 673 specimens of 10 species were captured. The LWR demonstrated a prevalence of species (six out of 10) with positive allometric growth (b > 3). The remaining species presented isometric (b = 3, two species) or negative growth (b < 3, two species). Native species exhibited the same LWR from previous studies, except Centropomus parallelus, which presented an isometric growth in this study. The non-native species Clarias gariepinus and Ictalurus punctatus showed significant differences between the LWR parameters in the Guaraguaçu River and in their native distribution, but the same growth pattern. Oreochromis niloticus did not present significant differences in the allometric coefficient from its native range. Conclusions These results indicate that different environmental conditions may not influence the growth pattern of non-native species, which explains their invasion success due to high adaptability to new environments.

RESUMO Mudanças morfoanatômicas ou fisiológicas em conjunto com mudanças no tamanho do corpo, são conhecidas como relações alométricas. O objetivo do estudo foi identificar os pontos de mudanças de crescimento de Centropomus com base na morfometria e morfogeometria dos otólitos. Foram coletados 455 indivíduos de C. undecimalis e 176 de C. parallelus, adquiridos com pescadores artesanais do estado de Alagoas, Brasil. Os otólitos sagitta foram medidos quanto ao comprimento, altura, perímetro, área e pesados. Os modelos potencial e polifásico foram ajustados entre o comprimento do peixe e o comprimento do otólito. Os morfotipos de otólitos são descritos por descritores de Fourier e índices de forma. O modelo polifásico detectou três fases de crescimento. A primeira stanza para C. undecimalis foi em 46,8 cm e a segunda em 75,9 cm. Já C. parallelus, a primeira foi em 18,8 cm e segunda em 41,2 cm. Cada stanza possui um morfotipo específico de otólitos em ambas as espécies. Os otólitos de C. undecimalis e C. parallelus exibiram mudanças alométricas ontogenéticas em seu padrão de crescimento com dois pontos de mudança de stanzas. As stanzas corresponderam a comprimentos específicos alcançados por indivíduos ao longo de seus ciclos de vida, como seu tamanho na maturidade e comprimento na reversão sexual.

ABSTRACT Morphoanatomical or physiological changes coupled with changes in body size are known as allometric relationships. The objective of this study was to identify the points of growth changes in Centropomus based on otolith morphometry and morphogeometry. For this purpose, 455 individuals of C. undecimalis and 176 of C. parallelus were collected from artisanal fishermen of the coast of the state of Alagoas, Brazil. The sagittal otoliths were measured for length, height, perimeter, area and weighed. The potential and polyphasic models were fitted between total fish length and otolith length. The morphotypes otoliths wen describe by form Fourier descriptors and shape indices. The polyphasic model detected three growth phases. The first stanza for C. undecimalis was at 46.8 cm and the second at 75.9 cm. For C. parallelus, it was at 18.8 cm and at 41.2 cm. Each stanza has a specific otoliths morphotype in both species. The otoliths of C. undecimalis and C. parallelus exhibited ontogenetic allometric changes in their growth pattern with two stanzas changing points. The stanzas corresponded to specific lengths reached by individuals over their life cycles, such as their size at maturity and length at sexual reversion.

Abstract Species included in the genus Dolops (Ichthyostraca: Argulidae) have been recorded from Southern and Central Africa, Australia, and mainly from South America, with no records from Central or North America. Specimens of Dolops bidentata, previously recorded only in South America, were collected in the state of Tabasco, southern Mexico, parasitizing the common snook, Centropomus undecimalis. Here, we provide the first record of the genus and the species in North America (Mexico) and the first molecular characterization of Dolops bidentata including 1 mitochondrial and 2 nuclear DNA markers, as well as a morphological description of the specimens. The newly generated molecular data were used to preliminarily investigate the phylogenetic relationships of Branchiura and to include Dolops bidentata in a phylogenetic hypothesis. Our results fail to recover the monophyly of Dolops; however, more investigations are needed before any taxonomic change is made.

Resumen Las especies incluidas en el género Dolops (Ichthyostraca: Argulidae) han sido registradas en el sur y centro de África, Australia y principalmente en América del Sur, sin registros de América Central o del Norte. Ejemplares de Dolops bidentata, previamente registrados solo en América del Sur, se recolectaron en el estado de Tabasco, al sur de México, parasitando al róbalo Centropomus undecimalis. En el presente trabajo proporcionamos el primer registro del género y de la especie en América del Norte (México) y proporcionamos la primera caracterización molecular de Dolops bidentata que incluye un marcador de ADN mitocondrial y 2 nucleares, así como una descripción morfológica de los especímenes. La información molecular recién generada se utilizó para investigar, preliminarmente, las relaciones filogenéticas de Branchiura y para ubicar a Dolops bidentata en una hipótesis filogenética. Nuestros resultados no logran recuperar la monofilia de Dolops, sin embargo, se necesitan más investigaciones antes de realizar cualquier cambio taxonómico.

Abstract Introduction: The fish Centropomusundecimalis ingests whole prey by swimming rapidly and extending its jaws. It is a non-violent predator that follows a predator-prey size relationship. Objective: To inform a case of predation of C. undecimalis, a disproportionally large prey. Methods: Freshly caught fish from El Carmen lagoon, Tabasco, Mexico, were examined. Results: a Gobionellus oceanicus that was 56% the length of its predator, was found inside a C. undecimalis; the prey was bent in the stomach of its predator and had a bite wound in the middle of its body. Conclusions: apparently, C. undecimalis caught the prey with a single bite and swallowed it by folding the body in half: prey length is not the only determinant of when a prey is successfully captured by this fish.

Resumen Introducción: El pez Centropomusundecimalis ingiere presas enteras nadando rápidamente hacia ellas y extendiendo sus mandíbulas. Es un depredador no violento que sigue una proporción de tamaño depredador-presa. Objetivo: Informar un caso de depredación de C. undecimalis, una presa desproporcionadamente grande. Métodos: Se examinó el pescado recién capturado de la laguna El Carmen, Tabasco, México. Resultados: dentro de un C. undecimalis se encontró un Gobionellus oceanicus que tenía el 56% de la longitud de su depredador; la presa estaba doblada en el estómago de su depredador y tenía una herida por mordedura en el medio. Conclusiones: aparentemente, C. undecimalis atrapó a la presa con un solo mordisco y se la tragó doblando el cuerpo por la mitad: la longitud de presa no es el único determinante de cuándo una presa es capturada con éxito por este pez.

Resumen Introducción: Las lagunas costeras son hábitats importantes para los peces costeros y juegan un rol esencial como áreas de crianza para muchas especies. Mientras que los efectos de la salinidad y la temperatura sobre la abundancia de los peces han sido bien documentados, las investigaciones sobre la influencia de las características del sustrato son más escasas. Objetivo: Investigar la correlación de la salinidad, la temperatura y las características del sedimento con las variaciones espaciales y temporales de la composición de la ictiofauna en las zonas someras de la laguna costera Barra de Navidad. Métodos: Se tomaron muestras de la ictiofauna con un chinchorro playero a lo largo de un periodo de dos años en cuatro sitios de la laguna. La salinidad y la temperaturadel agua se midieron simultáneamente con las operaciones de muestreo. Se determinaron el tamaño de partículas del sedimento y su contenido de materia orgánica en cuatro momentos a lo largo del periodo de muestreo.Métodos multivariantes fueronutilizados para el análisis de los datos. Resultados: Un total de 13 487 peces pertenecientes a 69 especies fueron recolectados, pero solo cinco taxones(Eucinostomus currani, Mugil setosus, Anchoa sp., Diapterus brevirostris, Centropomus robalito) conformaron más del 80 % de los individuos. Se encontraron diferencias significativas en la composición de la ictiofauna entre todos los sitios de muestreo y entre las estaciones del año. El análisis de redundancia mostró que los cambios en la ictiofauna estuvieron relacionados principalmente con el porcentaje de lodo y el contenido de materia orgánica del sedimento, como expresión de un gradiente espacial. La influencia de la salinidad y la temperatura fue significativa también, pero estas variables explicaron una proporción menor de la variabilidad observada y estuvieron relacionadas principalmente con los cambios estacionales. Conclusiones: El tamaño de las partículas del sedimento y el contenido de materia orgánica del mismo son los factores abióticos más importantes que influyen en los cambios espaciales de la composición de la ictiofauna. Los cambios estacionales estuvieron correlacionados con cambios en la salinidad y la temperatura, pero podrían estar vinculados también a procesos biológicos como la reproducción y el reclutamiento.

Abstract Introduction: Coastal lagoons are important habitats for coastal fishes playing an essential role as nursery areas for many species.While the effects of salinity and temperature on fish abundance spatial and temporal variation have been well documented, research on the influence of substrate characteristics is scarce. Objective: To investigatethe correlation of salinity, temperature and sediment characteristics with spatial and temporal variations of the ichthyofauna composition in Barra de Navidad coastal lagoon´s shallow zones. Methods: Samples of ichthyofauna were taken with a beach purse seine along a period of two years in four sites. Water salinity and temperature were measured simultaneously with fish sampling operations. Sediment particle size and organic matter content were determined four times at each site during the sampling period. Multivariate methods were used for data analyses. Results: A total of13 487 fish pertaining to 69 species were collected, but only five taxa (Eucinostomus currani, Mugil setosus, Anchoa sp., Diapterus brevirostris, Centropomus robalito) made up more than 80 % of the individuals. Significant differences among all sampling sites and between seasons were found for the ichthyofauna composition. Redundancy analysis showed that changes in ichthyofaunal composition were mainly related to the percentage of mud and organic matter in sediments expressing a spatial gradient. The influence of salinity and temperature was also significant, but these variables explained a smaller proportion of the observed variability and were related mainly to seasonal changes. Conclusions: Sediment particle size and organic matter content are the most important abiotic factors influencing spatial changes in shallow water ichthyofaunal composition. Seasonal changes were correlated with changes in salinity and temperature but could also be related to biological processes such as reproduction and recruitment.

ABSTRACT The aim of this study was to characterize the microbiota of the intestinal tract of robalo (Centropomus sp), from natural environment and captivity, and to isolate and identify bacteria with probiotic potential. The intestinal microbiota was characterized by metagenomics directed to the 16S rRNA gene. In addition, samples of intestinal mucus were cultured in MRS medium for bacterial isolation. Molecular identification was done by sequencing the 16S rRNA gene. Probiotic capabilities were evidenced by proteolytic and bacterial antagonism assays against Plesiomonas shigelloides, Aeromonas hydrophila, Aeromonas veronii and Vibrio harveyi. The most abundant bacterial genera were Clostridium, Photobacterium, Cetobacterium and Rubritepida. Bacterial species, including Klebsiella sp, two strains of Weisiella cibaria and Lactococcus sp were isolated on MRS agar from the intestinal tract. W. cibaria strains showed broad antagonistic spectrum and positive proteolytic activity.

RESUMEN El objetivo del estudio fue caracterizar la microbiota del tracto intestinal de robalo (Centropomus sp), proveniente de medio natural y cautiverio, además de aislar e identificar bacterias con potencial probiótico. La microbiota intestinal se caracterizó mediante metagenómica dirigida al gen 16S ARNr. Además, se sembraron muestras de mucus intestinal en medio de cultivo MRS para el aislamiento bacteriano. La identificación molecular se hizo mediante la secuenciación del gen 16S ARNr. Las capacidades probióticas se evidenciaron mediante ensayos proteolíticos y de antagonismo bacteriano frente a Plesiomonas shigelloides, Aeromonas hydrophila, Aeromonas veronii y Vibrio harveyi. Los géneros bacterianos con mayor abundancia fueron Clostridium, Photobacterium, Cetobacterium y Rubritepida. Las especies bacterianas, incluyendo Klebsiella sp, dos cepas de Weisiella cibaria y Lactococcus sp fueron aisladas en agar MRS a partir del tracto intestinal. Las cepas W. cibaria mostraron amplio espectro antagonista y actividad proteolítica positiva.

Resumen Esta revisión provee un resumen general de las investigaciones realizadas en los últimos 10 años acerca de los esteroides sexuales (17β-Estradiol, Testosterona, 11 Ketotestosterona y 17α, 20β-DHP), las gonadotropinas (Fsh y Lh) y sus principales reguladores (GnRH1-3 y GnIH1-3); y su respectiva función en la modulación de la reproducción. Específicamente sobre el eje Hipotálamo - Pituitaria - Gónada (HPG), en teleósteos modelo y neotropicales (Astyanax altiparanae, Steindachneridion parahybae, Salminus hillarii, Centropomus undecimalis). Mostramos que el papel regulador de éstos continúa siendo tema de discusión, pues varía en función de múltiples características, entre ellas, las estrategiareproductivas de la especie en cuestión y/o las condiciones en las que éstas son mantenidas durante el estudio. Históricamente, se ha descrito que la Fsh actúa en las fases tempranas de la reproducción, estimulando la biosíntesis de estradiol y testosterona necesarios para la gametogénesis; mientras la Lh está implicada en las fases finales del ciclo reproductivo (maduración final de los gametos y desove). Sin embargo, en especies con desarrollo asincrónico y desove múltiple, la Lh se produce durante todo el ciclo en paralelo con la Fsh, sugiriendo la necesidad de ambas hormonas en la gametogénesis y maduración final. Adicionalmente, investigaciones recientes en especies con comportamiento migratorio reproductivo, han evidenciado una disminución significativa en la expresión del ARNm de la subunidad β de Lh (lhb) cuando los individuos son mantenidos en cautiverio, lo que podría ocasionar alguna disfunción reproductiva bajo los actuales sistemas de cultivo, considerado hoy el gran problema de la acuicultura contemporánea. Desafortunadamente, los estudios de estos tópicos en especies suramericanas son aún incipientes, por lo que se hace necesario centrar las investigaciones hacia el esclarecimiento del control neuroendocrino de la reproducción en especies nativas, más aún cuando estas especies son mantenidas en cautiverio.

Abstract This review summarises research over the last 10 years regarding sex steroids (17β-estradiol, testosterone, 11 ketotestosterone and 17α, 20β-DHP), gonadotropins (Fsh and Lh), their main regulators (GnRH1-3 and GnIH1-3) and their functions in modulating reproduction. It focuses specifically on the hypothalamic-pituitary-gonadal (HPG) axis in model and Neotropical teleosts (Astyanax altiparanae, Steindachneridion parahybae, Salminus hillarii and Centropomus undecimalis). Their regulatory role continues to be a subject of discussion since it varies, depending on multiple characteristics such as the reproductive strategies of the species in question and/or the conditions in which these were maintained during the study period. It has been described that Fsh acts during the early stages of reproduction by stimulating the biosynthesis of estradiol and testosterone which are necessary for gametogenesis, whilst Lh is involved in the reproductive cycle’s final stages (final gamete maturation and spawning). However, Lh occurs throughout the cycle, in parallel with Fsh, in species having asynchronous development and multiple spawning, suggesting the need for both hormones during gametogenesis and final maturation. Recent research regarding species having reproductive migratory behaviour has highlighted a significant decrease in Lh β subunit (LHβ) mRNA expression when individuals are kept in captivity; this may have led to reproductive dysfunction in current culture systems, considered today as being the greatest problem facing contemporary aquaculture. Unfortunately, studying such topics related to South American species is still in its early stages so research must be focused on clarifying native species’ neuroendocrine control of reproduction, especially when these species are kept in captivity.

Resumo Esta revisão apresenta um resumo geral das pesquisas realizadas nos últimos 10 anos sobre os esteroides sexuais (17β-Estradiol, Testosterona, 11 Ketotestosterona e 17α, 20β-DHP), as gonadotrofinas (Fsh e Lh), seus principais reguladores (GnRH1-3 e GnIH1-3); e sua respetiva função na modulação da reprodução. Especificamente, sobre o eixo Hipotálamo - Pituitária - Gónada (HPG), em teleósteos modelos e neotropicais (Astyanax altiparanae, Steindachneridion parahybae, Salminus hillarii, Centropomus undecimalis). Mostra-se que o papel regulador deles continua sendo assunto de discussão, pois varia em função de múltiplas caraterísticas, por exemplo, as estratégias reprodutivas da espécie mencionada e/ou as condições experimentais. Historicamente, tem sido descrito que a Fsh atua nas fases iniciais da reprodução, estimulando a biossíntese de estradiol e testosterona necessários para a gametogéneses; enquanto a Lh está implicada nas fases finais do ciclo reprodutivo (maduração final das gametas e desova). No entanto, em espécies com desenvolvimento assíncrono e desova múltipla, a Lh é produzida durante o ciclo em paralelo com a Fsh, sugerindo a necessidade de ambos hormônios na gametogénese e a maduração final. Adicionalmente, pesquisas recentes em espécies com comportamento migratório reprodutivo evidenciam uma diminuição significativa na expressão do mRNA da subunidade β da Lh (lhb) quando os indivíduos são mantidos em cativeiro, o que poderia resultar em alguma disfunção reprodutiva sob os atuais sistemas de cultura, sendo considerado hoje o grande problema da aquicultura contemporânea. Desafortunadamente, os estudos desses tópicos em espécies sul-americanas ainda são incipientes, pelo que é necessário concentrar as pesquisas para o esclarecimento do controle neuroendócrino da reprodução em espécies nativas, principalmente quando essas espécies são mantidas em cativeiro.

ABSTRACT. The Pacific white snook, Centropomus viridis, is considered a species with high farming potential in Mexico due to its high economic value and overall demand in the national market. Growth in farmed fish is largely determined by the dietary regimen, which includes feeding frequency, rate, time, and cycle. The aim of the present study was to determine the feeding frequency and appropriate feeding time for farmed C. viridis juveniles in order to optimize growth and survival. Juveniles weighing 0.36 ± 0.01 g were used to evaluate 1 and up to 5 ad-libitum feeding frequencies per day, with 3 to 24-h intervals, for 6 weeks. Gained weight (GW), growth rate (GR), specific growth rate (SGR), food conversion ratio (FCR), feeding efficiency rate (FER), coefficient of variation (CV), hepatosomatic index (HI), peritoneal fat index (PFI), and survival (S) were determined for juveniles. Regardless of the feeding hours, no significant differences were found in the GR and SGR values between juveniles fed 3 times a day and those fed 5 times a day. FCR was significantly higher and FER significantly lower in treatments with juveniles fed only once a day compared with the rest of the treatments. No significant differences were found in CV, HI, and S between treatments. PFI was significantly different only between juveniles fed once and 5 times a day. Considering the results obtained in this study, we suggest feeding C. viridis juveniles 3 times a day at 6-h intervals between doses. These results will contribute to the development of biotechnology for farming this species.

RESUMEN. El robalo blanco del pacífico, Centropomus viridis, se considera como una especie con alto potencial para su cultivo en México por su alto valor económico y gran demanda en el mercado nacional. El crecimiento de los peces en cultivo depende, en gran medida, del régimen alimenticio, el cual incluye, frecuencia, tasa, tiempo y ritmo de alimentación. El presente trabajo tuvo como objetivo determinar la frecuencia y la hora apropiada de alimentación de juveniles de C. viridis en cultivo para optimizar el crecimiento y la supervivencia. Se utilizaron juveniles de 0.36 ± 0.01 g para evaluar de 1 a 5 frecuencias de alimentación ad libitum por día, con intervalos de 3 a 24 h, durante 6 semanas. Se determinó el peso ganado (PG), la tasa de crecimiento (TC), la tasa específica de crecimiento (TEC), la tasa de conversión alimenticia (TCA), la tasa de eficiencia alimenticia (TEA), el coeficiente de variación (CV), el índice hepatosomático (IH), el índice de grasa peritoneal (IGP) y la supervivencia (S) de los juveniles. La TC y la TEC de los juveniles alimentados 3 veces al día, independientemente de las horas de alimentación, no presentaron diferencias significativas con respecto a los resultados obtenidos para los juveniles alimentados 5 veces al día. La TCA fue significativamente mayor y la TEA significativamente menor en los tratamientos con juveniles alimentados una sola vez al día en comparación con el resto de los tratamientos. No se encontraron diferencias significativas en CV, IH y S entre los tratamientos. El IGP solo presentó diferencias significativas entre los juveniles alimentados 1 y 5 veces al día. Con base en los resultados obtenidos en el presente estudio, se sugiere que los juveniles de C. viridis se alimenten 3 veces al día, con un intervalo de 6 h entre cada toma. Estos resultados ayudarán en el desarrollo de la biotecnología de cultivo de esta especie.

Abstract This study poses two objectives: to determine whether the growth of females and males of the C. viridis is isometric, and whether the commercial fishing changes the condition of snook. The information regarding the length-weight relationship (LWR) is basic for the development of management strategies and conservation of the white snook. The length-weight relationship condition analysis is presented for the snook C. viridis fishery in the north coast of Nayarit. A non-experimental, longitudinal aleatory study was performed. Data was obtained during a six-year period (2010-2015). The weight, total length and sex of 2542 organisms were recorded. The LWR of males from 2010 to 2015 indicated negative allometric growth (p < 0.05), while the females indicated positive allometric growth (p < 0.05). However, the overall analysis LWR for males and females in the whole sampling period (2010-2015) showed negative allometric: b = 2.958 (p < 0.05) and r2 = 0.948. Regarding the analysis of condition, results indicated a value of Kn ≥ 1 in males; females presented a condition lower than 1, which indicated sex-change from male to female. In response to the fishing pressure, the C. viridis has readjusted year after year the minimum size of sex switching, generating slight variations of Kn in females of the C. viridis in the studied area.

Resumen Este estudio plantea dos objetivos: determinar si el crecimiento de hembras y machos de Centropomus viridis es isométrico, y si la pesca comercial cambia la condición del róbalo garabato. La información sobre la relación talla-peso (RTP) es básica para el desarrollo de estrategias de manejo y conservación del róbalo. El análisis de relación talla-peso y condición se presenta para la pesquería del robalo C. viridis en la costa norte de Nayarit. Se realizó un estudio aleatorio longitudinal no experimental. Los datos se obtuvieron durante un período de seis años (2010-2015). Se registró la talla el peso y el sexo de 2542 organismos. La RTP de los machos de 2010 a 2015 indicó un crecimiento alométrico negativo (p <0.05), mientras que las hembras indicaron un crecimiento alométrico positivo (p <0.05). Sin embargo, el análisis global LWR para machos y hembras en todo el período de muestreo (2010-2015) mostró alometría negativa: b = 2.958 (p <0.05) y r2 = 0.948. Con respecto al análisis de la condición, los resultados indicaron un valor de Kn ≥ 1 en machos; las hembras presentaron una condición inferior a 1, lo que indicaba que el cambio de sexo de hombre a mujer. En respuesta a la presión de pesca, C. viridis se ha reajustado año tras año el tamaño mínimo de cambio de sexo, generando ligeras variaciones en Kn de hembras de C. viridis en el área estudiada.

RESUMO: Óleos essenciais de plantas, cujo composto majoritário é o citral, mostraram efeitos benéficos quando adicionados à ração para peixes. O objetivo do presente estudo foi avaliar o efeito da adição de citral sobre os parâmetros zootécnicos e atividades das enzimas digestivas de Centropomus undecimalis. Os juvenis foram alimentados por 45 dias com dietas contendo diferentes quantidades de citral (0,0 - controle, 0,5, 1,0 e 2,0 mL por kg de ração). Os parâmetros de qualidade da água foram mantidos estáveis durante o experimento e nenhuma mortalidade foi observada. Ao final do período experimental, o tratamento 0,5 mL citral por kg de ração teve o menor ganho de peso e taxa de crescimento específico e a maior conversão alimentar, enquanto os mesmos parâmetros não diferiram entre os demais tratamentos. A atividade da pepsina foi maior no estômago de peixes alimentados com 0,5 mL de citral por kg de ração e a atividade de amilase foi maior no intestino de peixes alimentados com 0,5 e 2,0 mL citral por kg de ração comparado ao grupo controle. A atividade da lipase intestinal foi maior em todos os grupos que foram alimentados com citral, em comparação ao grupo controle. As atividades de quimotripsina e tripsina não mostraram diferença entre os grupos. Consequentemente, a adição de citral na ração em qualquer um dos níveis testados não é recomendada para robalo flecha.

ABSTRACT: Essential oils of plants whose main compound is citral showed beneficial effects when added to fish feed. The objective of the present study was to evaluate the dietary effect of the addition of citral on zootechnical parameters and digestive enzyme activities of Centropomus undecimalis. Juveniles were fed for 45 days with diets containing different amounts of citral (0.0 - control, 0.5, 1.0, and 2.0 mL per kg of diet). The water quality parameters were kept stable during the experiment and no mortality was observed. At the end of the experimental period, the treatment 0.5 mL citral per kg of diet had the lowest weight gain and specific growth rate, and the highest feed conversion, while the same parameters did not differ between the other treatments. Pepsin activity was higher in the stomach of fish fed with 0.5 mL citral per kg of diet and amylase activity was higher in the intestine of fish fed with 0.5 and 2.0 mL citral per kg of diet compared to the control group. Intestinal lipase activity was higher in all groups that were fed with citral compared to the control group. Chymotrypsin and trypsin activities showed no difference between groups. Consequently, dietary addition of citral at any of the levels tested is not recommended for common snook.

Resumo Sistemas de recirculação de água salgada utilizando alimentadores automáticos são uma nova fronteira para a aquicultura marinha. Possibilitam diminuir a vulnerabilidade dos cultivos em sistemas abertos e conferir redução de desperdício de ração e lançamento de efluentes, assim como elevar o retorno econômico. Foi realizado um experimento com juvenis de Robalo-flecha (4,31 ± 1,42 g e 8,4 ± 1,0 cm). Três frequências alimentares foram avaliadas: alimentação seis vezes ao dia; doze vezes ao dia, e; dezoito vezes ao dia. Cada tratamento teve três repetições. Dentre as três frequências avaliadas a frequência alimentar de 12 vezes ao dia foi a que apresentou os melhores valores para os parâmetros zootécnicos avaliados. Os valores obtidos de peso final, fator de condição, taxa de crescimento específico e ganho de peso diário foram todos maiores para a frequência de 12 vezes ao dia do que os obtidos para as frequências maior e menor. Nossos resultados demonstram que elevadas frequências alimentares não são sinônimo de melhor desempenho produtivo, mas é extremamente importante conhecer a frequência ideal para a espécie a ser cultivada. Além disto, a relação entre frequência alimentar e crescimento pode mudar de acordo com a faixa de peso dos indivíduos. Desta forma, é extremamente importante que trabalhos futuros avaliem as frequências aqui estudadas para comparar os resultados em indivíduos maiores.

Abstract Salt water recirculation systems using automatic feeders are a new frontier for marine aquaculture. It is possible to decrease the vulnerability of the traditional fish farming in open systems and reduce wasteful feeding and discharge of effluents, as well as increase the economic returns. An experiment with common snook fingerings (4.31 ± 1.42 g and 8.4 ± 1.0 cm) was performed. Three feeding treatments were evaluated: six, twelve and eighteen feeding times per day. Each treatment had three replications. Among the three tested frequencies (fed 6, 12 and 18 times a day), the feeding frequency of 12 times per day (every two hours) showed the best values of the parameters evaluated for production performance. The final weight values, condition factor, specific growth rate and daily weight gain of the treatment 12 feeding times per day were all significantly higher than the lower and higher frequencies. Our results demonstrate that high feeding frequency is not synonymous of higher performance, but is extremely necessary to find out the best range for the target species. Besides, this relationship between feeding frequency and growth performance might change over weight range. Therefore, future studies should address higher weight ranges for comparison to our results.

ABSTRACT The Mexican snook, Centropomus poeyi, supports an important fishery in southeastern Mexico. Due to its protandrous hermaphroditism, females may be especially sensitive to overfishing because they tend to be larger and selective removal has the potential to negatively affect natural populations, thus making urgent the need to contribute on management strategies for the species. The objective of this study was to produce batches of reproductive females at an early age and a small size by using 17β-estradiol (E2) in the diet. In two separate experiments, we fed fish 0, 10, 20, 30, 40, 50, or 60 mg of 17β-estradiol per kg of food for 60 days during gonadal differentiation. Fish fed with 50 and 60 mg of E2 per kg of food resulted in 100% feminization, while the control group (0 mg of E2) was 100% male. Three years after feminization, sex-reversed fish remained female, producing oocytes and were capable of spawning, while fish in the control group were ripe males with running milt. E2-treated groups were significantly larger (weight and length) than the control groups for up to six months after treatment, but the difference was undetectable at 300 days post-treatment. Survival was high in all treatments (100%). We obtained high percentages of functional females using dosages of 50 and 60 mg kg−1 of E2 for 60 days, with 80% of the induced fish spawning and producing fertilized eggs and larvae. The results obtained in this study provide opportunities for broodstock management and sex manipulation.