ARSENIC INDUCED ALTERATIONS IN GLYCOGEN AND LIPID DURING TESTICULAR CYCLE OF A FRESHWATER SILUROID, MYSTUS (M.) VITTATUS (BL.)

The increasing order in the glycogen and lipid content was observed during preparatory and spawning phase but decrease in these biochemical parameters was during post-spawning phase of testicular cycle in Mystus (M.) vittatus, a freshwater siluroid. Less signi?cant alteration in glycogen and lipid was noticed after 15 days of exposure but highly signi?cant decrease was observed after 30 days of exposure in SLC (Sublethal concentration) of trivalent arsenic as AsCl3. causes for decline in these biochemical parameters have been discussed.

The spawning method affects the reproductive efficiency of piracanjuba fish (Brycon orbignyanus) in restocking programs / El método de desove afecta la eficiencia reproductiva de piracanjuba (Brycon orbignyanus) en programas de repoblación / O método de desova afeta a eficiência reprodutiva de piracanjuba (Brycon orbignyanus) em programas de repovoamento

Abstract Background: Preserving the genetic diversity of wild fish is an important consideration for restocking programs, as inbreeding can compromise progeny survival as well as impact the resilience of natural populations. Objective: To evaluate the influence of spawning method: semi-natural (SN) or strip-spawning (ST), and the number of breeders (1♀:3♂ and 2♀:6♂) on the reproductive efficiency and genetic diversity of B. orbignyanus progeny destined for restoration of wild stocks. Methods: Rates of fertilization, hatching and broodfish mortality were recorded. For genetic evaluations (allele frequency, observed and expected heterozygosity, Shannon index, inbreeding coefficient, molecular variance analysis, and genetic differentiation), breeders (n=24), and their progenies (90 larvae/treatment) were sampled and analyzed using eight microsatellite markers. Results: Higher fertilization and hatching rates, and lower broodfish mortality were observed for the SN method (p<0.05), whereas the number of breeders did not affect these parameters (p>0.05). Interaction between spawning method and number of breeders was not significant (p>0.05). The amplified microsatellite loci produced a total of 30 alleles, with sizes between 80 and 225 bp and their frequencies indicated an increase (p<0.05) of genetic diversity in the progenies, but low genetic differentiation between treatments (p>0.05). Conclusion: The spawning methods and number of breeders tested increased equally the genetic diversity of the progeny, with low genetic differentiation between treatments. In contrast, rates of fertilization, hatching and brood fish mortality revealed that the SN method resulted in the best reproductive efficiency due to the handling stress and injuries caused by ST. Thus, SN proves to be the most suitable spawning-method for B. orbignyanus in restocking programs.

Resumen Antecedentes: Mantener la diversidad genética de los peces salvajes es una consideración importante para los programas de repoblación, ya que la endogamia puede comprometer la supervivencia de la progenie y afectar la supervivencia de las poblaciones naturales. Objetivo: Evaluar la influencia del método de desove (seminatural - SN o en franjas - ST) y el número de reproductores (1♀:3♂ y 2♀:6♂) sobre la eficiencia reproductiva y la diversidad genética de progenies de B. orbignyanus destinados a la restauración de poblaciones silvestres. Métodos: Se monitorearon las tasas de fertilización, eclosión y mortalidad de reproductores. Para las evaluaciones genéticas (frecuencias alélicas, heterocigosidad observada y esperada, índice de Shannon, coeficiente de endogamia, análisis de varianza molecular y diferenciación genética) los reproductores (n=24) y su progenie (90 larvas/tratamiento) se muestrearon y analizaron utilizando ocho marcadores microsatélites. Resultados: La interacción entre el método de desove y el número de reproductores no fue significativa (p>0,05). Se obtuvieron mejores tasas de fecundación y eclosión (p<0,05), y una menor mortalidad de reproductores (p<0,05) con el método SN, mientras que el número de reproductores no tuvo efecto (p>0,05). Los loci de microsatélites amplificados produjeron un total de 30 alelos con tamaños entre 80 y 225 pb, y sus frecuencias indicaron un aumento (p<0,05) en la diversidad genética de las progenies, pero una baja diferenciación genética entre tratamientos (p>0,05). Conclusión: Los métodos de desove y el número de reproductores evaluados aumentaron de la misma manera la diversidad genética de las progenies, con baja diferenciación genética entre tratamientos. En contraste, las tasas de fecundación, eclosión y mortalidad de peces reproductores revelaron que el SN tuvo la mejor eficiencia reproductiva, un hecho relacionado con el estrés del manejo y las lesiones causadas por el ST. Por lo tanto, el SN demuestra ser el método de desove más adecuado para B. orbignyanus en los programas de repoblación.

Resumo Antecedentes: A manutenção da diversidade genética dos peixes selvagens é uma importante consideração para programas de repovoamento, já que a endogamia pode comprometer a sobrevivência da progênie, além de impactar na resiliência das populações naturais. Objetivo: Avaliar a influência do método de desova (semi-natural - SN ou por extrusão - ST) e número de reprodutores (1♀:3♂ e 2♀:6♂) na eficiência reprodutiva e na diversidade genética de progênie de B. orbignyanus destinados à recuperação de estoques selvagens. Métodos: Taxas de fertilização, eclosão e mortalidade de reprodutores foram monitorados. Para avaliações genéticas (frequências alélicas, heterozigosidade observada e esperada, índice de Shannon, coeficiente de endogamia, análise de variância molecular e diferenciação genética), reprodutores (n=24) e sua progênie (90 larvas/tratamento) foram amostrados e analisados utilizando oito marcadores microssatélites. Resultados: Interação entre método de desova e número de reprodutores não foi significante (p>0,05). Melhores taxas de fertilização e eclosão (p<0,05), e menor (p<0,05) mortalidade de reprodutores foram observados para o método SN, enquanto que o número de reprodutores não afetou esses parâmetros (p>0,05). Os loci microssatélites amplificados produziram um total de 30 alelos, com tamanhos entre 80 e 225 pb e suas frequências indicaram aumento (p<0,05) da diversidade genética nas progênies, mas baixa diferenciação genética entre os tratamentos (p>0,05). Conclusão: Os métodos de desova e números de reprodutores avaliados aumentaram igualmente a diversidade genética das progênies, com baixa diferenciação genética entre tratamentos. Em contraste, as taxas de fecundação, eclosão e mortalidade de reprodutores revelaram que SN obteve a melhor eficiência reprodutiva, fato relacionado com o estresse de manipulação e injurias causadas por ST. Por isso, SN se mostrou como o método de desova mais adequado para B. orbignyanus em programas de repovoamento.

The genital and anal papillae of Compsura heterura (Characidae: Cheirodontinae): morphological structure and possible role in insemination

The function of the genital and anal papillae for insemination in Compsura heterura is discussed based on the description of their morphologies at different stages of the life cycle and during copulation and spawning. In males and females both the genital and anal papillae are involved in copulation in C. heterura. A pre-anal organ, anterior to the anus and stretched posteriorly, is present in adult males. The openings of the urinary channel and oviduct are separate in females. During copulation, there is an approximation between the female genital and anal papillae which become temporarily juxtaposed, forming a chamber enclosing the opening of the oviduct, which may also function in sperm capture. During spawning, the lateral edges of the female genital papilla are projected anteriorly, acquiring a tubular shape for oviposition.(AU)

A função das papilas genital e anal na inseminação em Compsura heterura é discutida com base na descrição de suas morfologias em diferentes estágios do ciclo de vida e por ocasião da cópula e desova. Em machos e fêmeas, as papilas genital e anal estão envolvidas na cópula. Um órgão pré-anal, anterior ao ânus e alongado posteriormente, está presente em machos adultos. Fêmeas possuem aberturas urinária e genital separadas. Durante a cópula, ocorre uma aproximação entre as papilas genital e anal femininas, que se justapõem temporariamente, formando uma câmara fechada onde se abre o oviduto, e que serve possivelmente à captura de esperma. Durante a desova, as bordas laterais da papila genital feminina são projetadas anteriormente, adquirindo um formato tubular para ovoposição.(AU)

Neonatal biometry and characterization of Amazonian Turtle nests (Podocnemis expansa)

The present study aimed to study the reproduction of the Amazon turtle (Podocnemis expansa) through the evaluation of the reproductive parameters of adult females. This study was carried out in the Crixás-Açu River, municipality of Mundo Novo, state of Goiás, Brazil. In September, the biometrics of 20 females were evaluated during the spawning period. Their nests were marked for subsequent evaluation of hatchlings, measuring the distances of each nest to the river and vegetation. The second stage consisted of the evaluation of hatchlings and characterization of nests after egg hatching. The datawere tested using the Pearson Correlation to measure the degree of linear correlation between the variables analyzed, such as the parameters of females, hatchlings, nests, and eggs. Nest depth was positively correlated with the number of eggshells found. We also found a correlation between the number of eggsshells and the distance of nests to the vegetation. Although moderate, this result indicates that as the distance to the vegetation increases, the number of eggshells found in nests decreases. The spawning site for Amazon turtle breeding is crucial to determine a higher number of eggshatching and better development of hatchlings. However, the literature is still very scarce regarding the choice of spawning grounds and the influence that vegetation may have on the development of freshwater turtle hatchlingsin Brazil.

Reproduction and fecundity of invader of internal insemination Trachelyopterus galeatus in a Neotropical floodplain

After the formation of Itaipu Reservoir, the invader Trachelyopterus galeatus colonized the upper Paraná River. Light microscopy was used to describe gametogenesis and the reproductive phases of females and males. The following data were verified: diameter of the oocytes, spawning type, batch fecundity by ovary weight, standard length, and total weight of the fish, along with the regions where this species reproduced in the upper Paraná River floodplain. A total of 470 specimens were collected quarterly in 2016, 2018 and 2019, and bimonthly in 2017. The gonads were fixed in a Karnovsky solution, dehydrated, infiltrated, and embedded in historesin. The histological slides were stained using PAS + iron hematoxylin + metanil yellow, analyzed and photographed under an image-capturing microscope. As regards diameter of the oocytes and fecundity estimates, ovaries whose oocytes were measured under a stereomicroscope were sampled. In the oogenesis, undifferentiated and differentiated oogonia, early primary growth oocytes, secondary growth oocytes, full-grown oocytes and maturing oocytes were recorded. In the spermatogenesis, primary and secondary spermatogonia, primary and secondary spermatocytes, spermatids and spermatozoa were recorded. The reproductive phases found for females and males were: immature, early development, late development, spawning/sperm-releasing capable, regression, and regeneration. Trachelyopterus galeatus prefers to occupy and reproduce in the Ventura, Patos, Guaraná, Fechada, Garças, and Pau Véio lagoons. The diameter of the oocytes varied from 0.4 to 2.9 mm. Females spawn, on average, 113 oocytes per batch. Batch fecundity variation shows that the larger the ovary, standard length, and total weight, the larger the number of oocytes to be spawned. This invader possesses reproductive success in the upper Paraná River floodplain, especially in lagoons.

Zygoparity in Characidae - the first case of internal fertilization in the teleost cohort Otomorpha

Most teleosts are externally fertilizing, with internal fertilization occurring as a relatively rare event. Until now, Euteleosteomorpha is the only teleost cohort known to undergo internal fertilization. In the teleost cohort Otomorpha, it has been recorded the presence of sperm in the ovaries of some species of Characiformes and Siluriformes, but no fertilized eggs have been found so far in the female reproductive tract. It has been presumed that oocytes can be released into the water with associated spermatozoa and only there becomes fertilized, and the term insemination has been used to characterize the strategy adopted by these fish. Here, we present the discovery of the first case of internal fertilization in the teleost cohort Otomorpha, in Compsura heterura (Characiformes: Characidae). In the course of spawning, the eggs form the perivitelline space and the animal and vegetative poles within the ovaries, evidencing oocyte fertilization. The newly spawned eggs then continue to form the animal and vegetative poles and increase the perivitelline space. These eggs are in the zygotic stage. These data indicate that fertilized eggs are only retained for a short period, providing evidence that C. heterura is a zygoparous fish.(AU)

A maioria dos teleósteos são espécies com fecundação externa, sendo a fecundação interna um evento relativamente raro. Até o momento, Euteleosteomorpha é a única coorte de teleósteos conhecida com espécies de fecundação interna. Na coorte de teleósteos Otomorpha, tem sido registrada a presença de esperma nos ovários de algumas espécies de Characiformes e Siluriformes, porém nenhum ovo fecundado foi encontrado até agora no trato reprodutor feminino. Presume-se que os oócitos possam ser liberados na água associados aos espermatozoides e que somente lá são fecundados, e o termo inseminação tem sido empregado para caracterizar a estratégia adotada por esses peixes. Apresentamos aqui a descoberta do primeiro caso de fecundação interna na coorte de teleósteos Otomorpha, em Compsura heterura (Characiformes: Characidae). Durante a desova, os ovos formam o espaço perivitelino e os polos animal e vegetal dentro dos ovários, evidenciando a fecundação interna. Os ovos recém-desovados continuam a formação dos polos animal e vegetal e aumentam o espaço perivitelino. Esses ovos estão na fase zigótica. Estes dados indicam que os ovos fertilizados são retidos por um curto período, fornecendo evidências de que C. heterura é um peixe zigóparo.(AU)

Early life history of the Caribbean coral Orbicella faveolata (Scleractinia: Merulinidae)

Introduction: Rehabilitation of hermatypic coral species that have declined in the Caribbean in recent decades is a priority. Production of sexual recruits is considered the best restoration method to aid affected populations. Objective: To gain knowledge of early life stages of Orbicella faveolata and to enhance production of new sexual recruits. Methods: Gamete bundles from the coral species O. faveolata were collected over two years (2018 and 2019) from Los Corales del Rosario y de San Bernardo Natural National Park, Cartagena, Colombia. Assisted fertilization, larval rearing, settlement (onto crustose coralline algae, CCA) and post settlement survival in laboratory conditions were monitored. Results: Embryonic and larval development were documented over 55 hours after the first cleavage, when larvae were fully developed and started pre-settlement behavior. Settlement began 7 days after first cleavage and after 37 days polyps had acquired zooxanthellae. Larval settlement was higher on Lythophyllum congestum and Titanoderma prototypum than in response to Porolithon pachydermum, Neogoniolithon sp., Hydrolithon sp., and Lythophyllum sp. Larvae did not settle on dead coral or on the negative control (sterilized seawater). After the first week post settlement survival was 59 % amongst O. faveolata recruits. During the second week, survival dropped to 42 %, and was further reduced to 0 % at the end of the third week. Conclusions: O. faveolata larvae require cues from certain CCA species to settle, they do not settle in absence of CCA. Increased larvae availability is possible through assisted fertilization in the laboratory, however, due to the high mortality in early post-settlement phases, additional research needs to be conducted in order to scale up larvae production and improve understanding of the cues that enhance settlement and the factors which cause post-settlement mortality.

Introducción: La rehabilitación de las especies de corales hermatípicos del Caribe que han disminuido en las últimas décadas es una prioridad. La producción de reclutas sexuales se considera el mejor método de restauración para ayudar a las poblaciones afectadas. Objetivo: Obtener conocimiento de las primeras etapas de la vida de O. faveolata y mejorar la producción de nuevos reclutas sexuales. Métodos: Por dos años (2018 y 2019), seis días después de luna llena en septiembre, se recolectaron paquetes gaméticos en arrecifes del Parque Nacional Natural Los Corales del Rosario y de San Bernardo, Cartagena, Colombia. Se siguió la fertilización asistida, la cría de larvas, el asentamiento y la supervivencia posterior al asentamiento en algas coralinas costrosas (ACC) en condiciones de laboratorio. Resultados: El desarrollo de embriones y larvas se documenta a lo largo de 55 h después del primer clivaje, cuando la larva está desarrollada completamente y comenzó el comportamiento previo al asentamiento. El asentamiento comienza 7 días después del primer clivaje y 37 días después, la mayoría de los pólipos presentan zooxantelas. El asentamiento larval fue más alto en Lythophyllum congestum y Titanoderma prototypum que en respuesta a Porolithon pachydermum, Neogoniolithon sp., Hydrolithon sp., y Lythophyllum sp. No hubo asentamiento sobre coral muerto ni en el control negativo (agua de mar esterilizada). La supervivencia bajó de un 59 % en la primera semana después del asentamiento, a 42 % durante la segunda semana y 0 % para el final de la tercera semana. Conclusiones: Las larvas de O. faveolata requieren señales de ciertas especies de ACC para asentarse, ellas no se asientan en ausencia de ACC. La disponibilidad de larvas es posible mediante la fertilización asistida en laboratorio. Sin embargo, debido a la alta mortalidad en las primeras fases posteriores al asentamiento, queda mucho por hacer para aumentar la producción de larvas y mejorar nuestro conocimiento y comprensión de las señales que mejoran el asentamiento y las que previenen o inhiben la supervivencia del recluta.

Effects of the environmental temperature and humidity on the survival and reproduction of Oncomelania snails in field experimental base / 公共卫生与预防医学

Objective To study the effects of environmental temperature and humidity on the survival and reproduction of Oncomelania snails, and to provide a basis for the development of scientific strategies and measures for snails control. Methods Based on the field experimental base of Oncomelania snails in Hubei Province, through long-term and systematic ecological observation of snails, the living conditions of snails at different temperatures were recorded, and the average densities of live snails and young snails as well as the amount of spawning were calculated. Results In a certain temperature range (15°C-30°C), the average densities of live snails and young snails were positively correlated with the changes of temperature and humidity, and the effect of temperature on the spawning of snails was also significant. The optimal breeding temperature of Oncomelania snails was 25°C. Conclusion In a certain temperature range (15°C-30°C), the environmental temperature and humidity have a significant impact on the survival and reproduction of snails in the field.

Reproducción en cautiverio de vizcaína Curimata mivartii con extracto pituitario de carpa / Captivity reproduction of vizcaina Curimata mivartii induced with extract of carp pituitary / Reprodução em cativeiro de vizcaína Curimata mivartii com extrato de hipófise de carpa

Resumen Con el objetivo de reproducir vizcaína Curimata mivartii, ejemplares de dos años de edad (n= 54), mantenidos en estanques en tierra (0,1 pez/m2) fueron inducidos con extracto pituitario de carpa (EPC) (Argent, USA) a razón de 6 mg/Kg de peso para las hembras en dos aplicaciones (10 % y 90% con 12 horas entre aplicación); mientras que los machos fueron inducidos con 4,8 mg/Kg EPC en dosis única. Antes de la inducción hormonal a cada hembra le fue realizada biopsia para verificar su estado de maduración gonadal. La muestra de ovocitos fue tratada con solución Serra (Chemí, Colombia) y después de tres minutos, con la ayuda de un estereoscopio de luz, (Leica, EZ4 W, Alemania) en objetivo de 4x, se determinó posición de la vesícula germinal (céntrico, migrando, periférico, sin núcleo). El análisis de la biopsia ovárica mostró que las hembras se encontraban en maduración final. Los machos inducidos se encontraron en fase de espermiación; los cuales a ligera presión abdominal liberaron líquido seminal. Se estimó el índice de ovulación, fecundidad (absoluta y relativa), diámetro de los ovocitos y volumen seminal. El porcentaje de fertilidad fue estimado a las cuatro horas post-eclosión (hpe) y el porcentaje de eclosión fue estimado a las 10 hpe. Las hembras ovularon entre 5 y 6 horas (28±1,0°C) e inmediatamente los huevos fueron obtenidos por extrusión, así como el semen. La fecundidad absoluta fue de 178331,6±28773,7 ovocitos/hembra y la relativa 137,7±19,6 g ovocitos/Kg de hembra. El diámetro de los ovocitos recién desovados fue de 687,2±42,8 µm. La fertilidad fue de 90,7±1,4% y la eclosión de 85,3±1,5%. Los resultados permiten concluir que EPC a dosificación de 6mg/Kg de peso es un buen inductor de la reproducción de vizcaína, con alto índice de ovulación y altos porcentajes de fertilidad y eclosión.

Abstract With the aim of reproducing the vizcaina Curimata mivartii, two-year-old specimens (n = 54), kept in ponds on land (0,1 fish/m2) were induced with carp pituitary extract (EPC) (Argent, USA) at a doses of 6 mg/Kg of weight for females in two applications (10% and 90% with 12 hours between applications), while males were induced with 4,8 mg / Kg EPC in a single dose. Before the hormonal induction, each female underwent an ovarian biopsy to verify the oocytes maturation stage. The oocyte sample was treated with Serra solution (Chemi, Colombia) and after three minutes, with the help of a light stereoscope (Leica, EZ4 W, Germany) in 4x objective, the position of the germinal vesicle was determined (central, migrating, peripheral, breakdown). The analysis of the ovarian biopsy showed that the females were in final maturation. Induced males were found in the spermiation phase; which at light abdominal pressure released seminal fluid. The ovulation index, fecundity (absolute and relative), oocyte diameter and seminal volume were estimated. The percentage of fertility was estimated at four hours after hatching (hah); and the hatching percentage was estimated at 10 hah. The females ovulated between 5 and 6 hours (28±1,0°C) and immediately the eggs were obtained by extrusion, as well as the semen. The absolute fecundity was 178331,6±28773,7 oocytes/female and the relative 137,7±19,6 g oocytes/Kg of female. The diameter of the newly spawned oocytes was 687,2±42,8 µm. Fertility was 90,7±1,4% and hatching 85,3±1,5%. The results allow to conclude that EPC at dosage of 6mg/Kg of weight is a good inducer of the vizcaína reproduction, which high ovulation index and high rates of fertility and hatching.

Resumo Com o objetivo de reproduzir vizcaína Curimata mivartii, espécimenes de dois anos de idade (n = 54), mantidos em tanques em terra (0,1 peixes / m2) foram induzidos com extrato de hipófise de carpa (EPC) (Argent, USA) a uma taxa de 6 mg / kg de peso para as fêmeas em duas aplicações (10% e 90% com 12 horas entre aplicações), enquanto os machos foram induzidos com 4,8 mg / kg de EPC em dose única. Antes da indução hormonal para cada fêmea, uma biópsia ovariana foi realizada para verificar o seu estado de maturação gonadal. A amostra de oócitos foi tratada com solução de Serra (Chemi, Colômbia) e após três minutos, com auxílio de um estereoscópio de luz (Leica, EZ4 W, Alemanha) em objetivo 4x, foi determinada a posição da vesícula germinativa (central, migrando, periférico, sem nucleo). A análise da biópsia ovariana mostrou que as fêmeas estavam em maturação final. Os machos induzidos foram encontrados na fase de espermizaҫã; que na pressão abdominal leve liberou fluido seminal. O índice de ovulação, fecundidade (absoluta e relativa), diâmetro do oócito e volume seminal foram estimados. A percentagem de fertilidade foi estimada em quatro horas pós-eclosão (hpe); enquanto a porcentagem de eclosão foi estimada em 10 hp. As fêmeas ovularam entre 5 e 6 horas (28±1,0°C) e imediatamente os ovos foram obtidos por extrusão, assim como o sêmen. A fecundidade absoluta foi 178331,6±28773,7 oócitos / fêmea e a relativa 137,7±19,6 g oócitos / kg de fêmea. O diâmetro dos oócitos recém-gerados foi 687,2±42,8 µm. A fertilidade foi de 90,7±1,4% e incubação de 85,3±1,5%. Os resultados permitem concluir que a EPC na dosagem de 6mg/Kg de peso é um bom indutor de reprodução de vizcaína, com alto índice de ovulação e altas taxas de fertilidade e eclosão.

Reproductive indicators of the endemic species Astyanax bifasciatus (Teleostei: Characidae) in a tributary of the Lower Iguaçu River Basin, Brazil

The reproductive process promotes morphophysiological and behavioral changes in fish species throughout their life cycle. Its success is vital to define their resilience in the environment. This study aimed to evaluate the reproductive biology of the endemic fish species Astyanax bifasciatusin a tributary of the Lower Iguaçu River Basin, Paraná, Brazil. Fish were collected monthly at four sites along the Jirau Alto River in the city of Dois Vizinhos from October 2015 to September 2016. A standardized catch effort with gill nets and fish traps was used. In the laboratory, standard length and total weight were recorded. After anesthesia, the animals were sectioned to macroscopically determine the sex, sexual maturity stage, and presence of celomatic fat. The gonads and liver were removed to determine the gonadosomatic and hepatosomatic indexes, respectively. A total of 160 individuals (104 femalesand 56 males) were used. The gonadosomatic index, frequency of the gonadal maturation stages, and condition factor showed a long reproductive period with two investment cycles for both sex. Length at first sexual maturity was 4.57 cm for females and 3.56 cm for males. The reproductive data corroborate the generalist profile of the species and demonstrate a high degree of adaptive capacity, even in smaller tributaries.

Variation in the structure of the ichthyoplankton community in the lower Paraíba do Sul River

The Paraíba do Sul River is affected by extensive water collection for supply, organic and industrial pollution, and dams. Nonetheless, the ichthyofauna maintains biodiversity and sustains artisanal fisheries. This study analyzes the composition, abundance and distribution of fish larvae, an important approach to determine the reproductive period and spawning sites. The sampling occurred from August 2011 through February 2013 in five sites at a transect between the banks on the lower reach of the Paraíba do Sul River. A total of 5,412 larvae belonging to 20 taxa was captured. The predominant order was Characiformes. Larvae of Prochilodus spp. and Leporinus spp. were the most abundant; larvae of Brycon insignis, an endangered species, were present. Fewer larvae were collected in the second reproductive cycle during a severe drought. The absence of eggs indicates that the study area is not used for spawning, and highlights the need for studies in the main channel and in the tributaries of the Paraíba do Sul River. Fish larvae need to have access to the marginal lagoons along the lower stretch of the river, an area which is the object of disputes between fishermen and farmers.(AU)

O rio Paraíba do Sul é afetado por retirada de água para abastecimento, poluição orgânica e industrial e barramentos, mas mantém a biodiversidade de peixes e sustenta a pesca artesanal. Este estudo apresenta a composição, abundância e distribuição de larvas de peixes, abordagem importante para determinar o período de reprodução e locais de desova. A amostragem ocorreu entre agosto de 2011 e fevereiro de 2013 em cinco pontos de um transecto de 500 m entre as margens no trecho inferior do rio Paraíba do Sul. Um total de 5.412 larvas de 20 táxons foi capturado. Predominaram Characiformes, sendo que larvas de Prochilodus spp. e Leporinus spp. foram as mais abundantes. Larvas de Brycon insignis, espécie em extinção, foram registradas. Larvas foram menos abundantes no segundo ciclo reprodutivo, coincidindo com o início de uma seca severa na região. A ausência de ovos nas amostras indica que a área estudada não é utilizada para desova e aponta a necessidade de estudos no canal principal a montante e nos afluentes. Ressaltamos a necessidade de acesso das larvas às lagoas marginais no trecho inferior do rio Paraíba do Sul, área objeto de desentendimentos entre pescadores e agricultores.(AU)

Spatial distribution and habitat use by early fish stages in a dammed river basin, Southern Brazil / Distribución espacial y uso de hábitat de peces en estadios tempranos de una represa del sur de Brasil

Abstract Fish diversity loss is threatened by the construction of dams as they prevent the regular natural dispersal among populations. Thus, conservation of key riverine habitats for fish reproduction may be essential for the recruitment of new native species of fish. The present study aimed to identify key habitats for fish spawning and early development in the Paranapanema River basin, as well as to determine the taxonomic composition, reproductive and life-history strategy, and to report spatial distribution of eggs, larvae and juveniles. The importance of lagoons, tributaries, and sub-tributaries was evaluated in the Paranapanema River basin between October 2012 and March 2013. Eggs and larvae samples were collected at dawn and dusk with conical plankton nets (0.5 mm mesh size), whereas juveniles were captured during the day with seine and sieve (0.5 cm mesh size). A total of 547 eggs, 904 larvae and 1 228 juveniles were captured. We observed that 2 larvae and 288 juveniles of non-migratory species, parental care, and equilibrium life-history strategy, predominated in lagoons and tributaries. On the other hand, 13 larvae and 60 juveniles of short migratory distance, no parental care, and periodic life-history strategy predominated in sub-tributaries. The highest densities of eggs were recorded in tributaries and sub-tributaries (Tukey's test, P = 0.001 and P = 0.03, respectively), and the highest densities of larvae were recorded for lagoons and tributaries (P = 0.005 and P = 0.0001, respectively). Captures of eggs and larvae were higher at night; while the highest catches per unit effort of juveniles were recorded for tributaries and sub-tributaries. Fish species that adopt different life-history strategies can use diverse types of habitats during the early stages. Lagoons, tributaries and sub-tributaries of the Paranapanema River play different roles in the reproductive success of fish fauna in a heavily modified basin. The preservation of spawning and nursery areas trapped between reservoirs is necessary for Neotropical fish species recruitment and survival. Rev. Biol. Trop. 66(2): 605-621. Epub 2018 June 01.

Resumen Los riesgos de pérdida de diversidad de peces aumentan con la construcción de represas, ya que impide la dispersión de individuos entre las poblaciones. Por lo tanto, la conservación del habitat ribereño clave para la reproducción de peces puede ser esencial para el reclutamiento de nuevos individuos de especies nativas. El presente estudio tiene como objetivo identificar hábitats clave para el desove y el desarrollo temprano de peces en la cuenca del río Paranapanema, así como determinar la composición taxonómica, la estrategia reproductiva y la historia de vida, y reportar la distribución espacial de huevos, larvas y juveniles. Se evaluó la importancia de lagunas, afluentes y subafluentes en la cuenca del río Paranapanema entre octubre de 2012 y marzo de 2013. Se recogieron muestras de huevos y larvas al amanecer y al atardecer con redes de plancton cónico (tamaño de malla de 0,5 mm), mientras que los juveniles fueron capturados durante el día con redes de cerco y tamiz (tamaño de malla de 0,5 cm). Se capturaron un total de 547 huevos, 904 larvas y 1 228 juveniles. Como resultado fue observado que 2 larvas y 288 juveniles de especies no migratorias, cuidado parental y estrategia de vida de equilibrio son predominantes en lagunas y afluentes. Por otro lado, 13 larvas y 60 juveniles de espécies migratorias de corta distancia, sin cuidado parental y estrategia de vida periódica predominaron en subafluentes. Se registraron las densidades más altas de huevos para afluentes y subafluentes (Prueba de Tukey, P = 0.001 y P = 0.03, respectivamente), y se registraron las densidades más altas de larvas para las lagunas y afluentes (P = 0.005 y P = 0.0001, respectivamente). Las capturas de huevos y larvas eran más altas por la noche. Las mayores capturas por unidad de esfuerzo de juveniles se registraron para los afluentes y subafluentes. Las especies de peces que adoptan diferentes estrategias de historia de vida pueden utilizar diversos tipos de hábitats durante las primeras etapas. Lagunas, afluentes y subafluentes del río Paranapanema desempeñan diferentes papeles en el éxito reproductivo de la fauna de peces en una cuenca fuertemente modificada. La preservación de áreas de desove y cría atrapadas entre el embalse es necesaria para el reclutamiento de especies de peces neotropicales.

Reproduction of Megapitaria squalida (Bivalvia: Veneridae) in the Southeast Gulf of California, Mexico / Reproducción de la almeja callista Megapitaria squalida (Bivalvia: Veneridae) en el sureste del Golfo de California, México

AbstractBivalves reproductive cycle varies according to the particular environmental conditions where they are found, and these reproductive details represent basic information for their capture, management and conservation strategies. With this objective, the reproductive cycle of the clam Megapitaria squalida, inhabiting the Southeast of the Gulf of California (Altata Bay, Sinaloa, Mexico), was studied using histology and changes in the number and size of oocytes, from June 2013 to June 2014. Histological analysis of the gonads showed spawning activity throughout the year, with two peaks. The first was registered in October and it was accompanied by the highest decrease of weight; the second was in February with the highest percentage of spawning population; besides, a resting period was observed in December. The sex-ratio (female:male) of the clam population was 1.08:1 (χ2 = 5.72, d.f. = 1, P < 0.05). Mean oocyte size and number were different (P < 0.05) among all sampling months and fluctuated from 34.6 ± 5.8 µm in June 2014, to 41.9 ± 6.8 µm in February 2014, and from 443.8 ± 424.5 in February 2014, to 1 214.4 ± 267.6 counted in April, respectively. With these results we suggest a protection season from October to November, when the most intense release of gametes occur in this population. Rev. Biol. Trop. 65 (3): 881-889. Epub 2017 September 01.

ResumenEl ciclo reproductivo de los bivalvos varía de acuerdo a las condiciones ambientales de cada lugar, y representa información importante para su conservación. Se estudió el ciclo reproductivo de la almeja Megapitaria squalida utilizando cortes histológicos de la gónada y cambios en el número y tamaño de los oocitos, en el sur del Golfo de California (Bahía Altata, Sinaloa, México), desde junio 2013 a junio 2014. El análisis histológico de las gónadas, mostró eventos de desove todo el año con dos picos: el primero fue registrado en octubre acompañado con un fuerte decremento en peso de los animales; el segundo en febrero caracterizado por un alto porcentaje de desove en la población. Se observó un periodo de reposo en diciembre. La proporción sexual (hembras:machos) de la población de almejas fue 1.08:1 (χ2 = 5.72, g.l. = 1, P < 0.05). El número y tamaño promedio de los oocitos mostró diferencias (P < 0.05) entre los muestreos mensuales, y fluctuaron de 34.6 ± 5.8 µm en junio 2014 a 41.9 ± 6.8 µm en febrero 2014, y de 443.8 ± 424.5 en febrero 2014, a 1 214.4 ± 267.6 en abril 2014. Se propone una temporada de veda desde octubre a noviembre, ya que en estos meses la liberación de gametos por la población fue más intensa.

Ovarian histology and fecundity in the evaluation of the reproduction of the invasive species Serrasalmus marginatus (Characidae) on a neotropical floodplain / Histologia ovariana e fecundidade na avaliação da reprodução da espécie invasora Serrasalmus marginatus (Characidae) em uma planície de inundação neotropical

The construction of the Itaipu Hydroelectric Power Plant in 1982 led to the formation of a reservoir, which, in turn, leveled the waters of the Paraná River by flooding the geographic barrier Salto de Sete Quedas. This allowed the piranha Serrasalmus marginatus to invade and colonize the upper Paraná River. This study aimed to: i) confirm, through light microscopy, the reproductive phases of S. marginatus females; ii) estimate fecundity and iii) evaluate the reproduction areas of the population. A total of 764 females were collected from nine sampling sites on the upper Paraná River floodplain. Microscopic analysis of the ovaries showed the following phases: early developing subphase, developing phase, spawning capable phase, actively spawning subphase, regressing phase and regenerating phase. The frequency distribution of the oocytes shows that spawning is fractional and fecundity indeterminate. Fecundity varied from 410 to 752 oocytes (mean = 584). The continual spawning of oocytes during the long reproductive period, as well as the aggressiveness of the species as regards the defense of its offspring, guarantees more descendants in the Patos, Ventura, Fechada, Guaraná and Garças lagoons and Ivinheima and Baia rivers of the upper Paraná River floodplain.

A construção da Usina Hidroelétrica de Itaipu, em 1982, levou a formação do reservatório que por sua vez nivelou as águas do rio Paraná inundando a barreira geográfica do salto de Sete Quedas. Isto permitiu que a piranha Serrasalmus marginatus invadisse e colonizasse o alto rio Paraná. Este estudo teve por objetivos: i) confirmar através da microscopia de luz as fases reprodutivas das fêmeas de S. marginatus; ii) estimar a fecundidade e iii) avaliar as áreas de reprodução da população. Um total de 764 fêmeas foram amostrados em nove estações de amostragem na planície de inundação do alto rio Paraná. A análise microscópica dos ovários mostrou fêmeas nas subfases em desenvolvimento inicial, fase desenvolvimento, fase apto à desova, subfase desova ativa, fase regressão e fase regeneração. A distribuição de frequência dos oócitos mostra que a desova é parcelada e a fecundidade é indeterminada. A fecundidade variou de 410 a 752 e em média 584 oócitos. A desova contínua durante o longo período reprodutivo associado à agressividade em relação à defesa da prole garante o sucesso em deixar mais descendentes nas lagoas dos Patos, Ventura, Fechada, do Guaraná, das Garças, nos rios Ivinheima e Baia da planície de inundação do alto rio Paraná.

Las agregaciones de desove de Tylosurus pacificus (Beloniformes: Belonidae) y su pesca en el Parque Nacional Natural Utría (Pacífico colombiano) / Spawning aggregations of Tylosurus pacificus (Beloniformes: Belonidae) and their fishery in Utría Park, Colombian Pacific

ResumenAlgunas especies de peces marinos tienen complejas relaciones con los ecosistemas costeros durante sus periodos reproductivos, tal es el caso del pez aguja Tylosurus pacificus, que conforma agregaciones de desove en playas de grava en el Parque Nacional Natural Utría. Se describe la actividad pesquera y algunos aspectos de la biología reproductiva de T. pacificus y se proponen algunas medidas para mitigar el impacto sobre este evento y los procesos ecológicos asociados. Se realizó un monitoreo pesquero entre abril 2008 y febrero 2009 en el Parque Nacional Natural Utría (PNNU), Pacífico colombiano. Se analizaron los volúmenes de captura, estructura por talla, proporción de sexos y fecundidad (n= 84). La longitud total osciló entre 60.5 cm y 104 cm con una media y desviación estándar de 85.35 ± 9.09 cm. La fecundidad promedio fue 189 685.56 ovocitos por gónada, con una moda de 8 mm de diámetro y un desarrollo gonadal asincrónico. La especie desova en forma colectiva en la playa cuando la marea alcanza el nivel más alto durante la luna llena y nueva, generalmente al anochecer. Pescadores que habitan los pueblos cercanos aprovechan este recurso, durante la agregación reproductiva de la especie. Es importante ampliar el estudio de la reproducción de T. pacificus y los procesos ecológicos asociados a su desove para poder dar un aprovechamiento adecuado y garantizar la sostenibilidad de su pesquería a largo plazo.

Abstract:Some species of marine fish have complex relationships with coastal ecosystems during their reproductive periods, as the needle fish Tylosurus pacificus that forms spawning aggregations in gravel beaches in Utría Park. We described fishery and some aspects of the reproductive biology of T. pacificus and proposed some strategies to mitigate the impact of this event and associated ecological processes. Fisheries monitoring were conducted between April 2008 and February 2009 in the Utría National Park, Colombian Pacific. Catch volumes, length structure, sex ratio and fecundity (n= 84) were analyzed. The total length ranged among 60.5 and 104 cm with a mean and standard deviation of 85.35 ± 9.09 cm. The average fertility of oocytes per gonad was 189 685.56, with a mode of 8 mm diameter and an asynchronous gonadal development. This species spawns collectively on the beach when the tide reaches the highest level during full and new moon, usually in the evening. Fishermen of a near town take advantage of the spawning aggregation of this species. The reproduction study of T. pacificus and ecological processes associated with their spawning, should be expanded to give adequate use, and ensure the sustainability of their fishery over the long term. Rev. Biol. Trop. 65 (1): 77-87. Epub 2017 March 01.

Parámetros biológicos básicos para la conservación de Pseudocurimata lineopunctata (Characiformes, Curimatidae) en el Río Anchicayá, Valle del Cauca, Colombia / Basic biological parameters for Pseudocurimata lineopunctata (Characiformes, Curimatidae) conservation in the Anchicayá River of the Cauca Valley, Colombia

ResumenPseudocurimata lineopunctata representa un importante aporte nutricional para las comunidades locales en Colombia y Ecuador. A pesar que su captura anual es baja (590 kg/año), no hay restricciones sobre el tamaño mínimo, y esta especie está catalogada como vulnerable en riesgo de extinción moderada por la Corporación Autónoma Regional del Valle del Cauca (Colombia). Para apoyar los programas de conservación, se requiere de datos biológicos de las especie. Por lo tanto, los objetivos de este estudio fueron describir la proporción de sexos, la distribución, el tamaño en relación al peso, las fases macroscópicas de la madurez reproductiva, fecundidad y talla de primera madurez sexual para P. lineopunctata. Las muestras de peces fueron capturados con redes por nueve meses (Febrero-Octubre) en 2007. La longitud total (Lt) de los peces capturados varió entre 10.7 y 16.5 cm, con peso total (Pt) entre 25.0 y 67.5 g. Las hembras representaron el 52.6 % del grupo de muestra mientras que los machos el 47.4 %, y se observaron diferencias en la proporción de sexos en relación con el tamaño del pez. Durante todos los meses muestreados se capturaron ejemplares en estado de madurez avanzado. Con base en el análisis de los índices gonadosómatico, (IGS), gonádico (IG) y de condición (K), se postula que habría dos máximos de desove, uno de junio-julio y otro en septiembre-octubre. La talla de primera madurez sexual para las hembras fue determinada en 9.2 cm y para los machos en 10.1 cm de Lt. La fecundidad absoluta fue estimada en 3 598 ovocitos/♀, con una fecundidad relativa de 84 ovocitos/g♀. Se hace necesario realizar investigaciones adicionales que aumenten la información sobre la reproducción de esta especie, con la finalidad de apoyar futuros programas de repoblamiento.

Abstract:Pseudocurimata lineopunctata represents an important nutritional source for local human communities in Colombia and Ecuador. Although the yearly catch of this fish is low (590 kg/year), there are no restrictions on minimum size, and this species is categorized as vulnerable with moderate extinction risk by the Regional Autonomous Corporation of the Cauca Valley (Colombia). To support conservation programs, biological data of the target species are required. Therefore, the aims of this study were to describe the sex ratio, distribution, size to weight ratio, macroscopic stages of reproductive maturity, fecundity, and size at first sexual maturity for P. lineopunctata. For this, fish samples were captured with nets over nine months (February-October) in 2007. The total length (Lt) of the captured fish ranged between 10.7 and 16.5 cm, with total weight (Pt) between 25.0 and 67.5 g. Females represented 52.6 % of the sample group while males represented 47.4 %, and differences in sex ratio were observed in relation to fish size. For all sampled months, the fish captured showed an advanced maturity state. Based on analyses of the gonadosomatic index (IGS), gonadic index (IG), and Fulton's condition factor (K), and two spawning peaks were determined, one in June-July, and the other in September-October. The size at first sexual maturity was 9.2 cm for females and 10.1 cm for males. Absolute fecundity was estimated as 3 598 oocytes/ g♀. It is necessary to carry out additional investigations on the reproduction of this species, to support future repopulation programs. Rev. Biol. Trop. 65 (1): 239-253. Epub 2017 March 01.

Potencial reprodutivo de Pagrus pagrus (Perciformes: Sparidae) em águas costeiras da província de Buenos Aires (Argentina) e Uruguai (34º-39ºS)

The reproductive potential of red porgy in coastal waters of Buenos Aires Province (Argentina) and Uruguay (34º-39ºS) was studied by means of a macroscopic and histological analysis of the gonads. Length and age at first maturity were determined, and fecundity, spawning frequency and egg quality were estimated. The spawning season extended from spring through summer between October and January with a peak of spawning in December. Length and age at maturity for sexes combined was 24.5 cm TL and 1.54 years, respectively. Batch fecundity ranged from 6,974 (25 cm TL) to 110,725 (39 cm TL) hydrated oocytes and showed significant linear relationships with total length and ovary-free weight. Relative fecundity ranged from 16 to 172 oocytes per female gram (ovary free). Spawning frequency was 58.5% during January 2011, indicating that females spawned once every 1-2 days at the peak of the spawning season. The life history of red porgy in Argentina and Uruguay was characterized by a young age at first maturity and partial, almost daily, spawning in a bounded time period, a life history strategy that would facilitate population expansion or colonization of new areas, and high population recovery rates or growth (r).(AU)

Se analizó el potencial reproductivo del besugo en aguas costeras de la provincia de Buenos Aires (Argentina) y Uruguay sobre la base del análisis macroscópico e histológico de las gónadas. Se determinó la talla y edad de primera madurez sexual y se estimaron la fecundidad, frecuencia de puesta y calidad ovocitaria. Se pudo establecer que la actividad reproductiva del besugo acontece durante primavera-verano, entre octubre y enero, con un pico de desove principal en diciembre. La estimación de la talla y edad de primera madurez para ambos sexos fue de 24,5 cm LT y 1,54 años respectivamente. La fecundidad parcial presentó un ajuste lineal con la talla y el peso de la hembra y varió entre 6.974 (25 cm LT) y 110.725 (39 cm LT) ovocitos hidratados. La fecundidad relativa osciló entre 16 y 172 ovocitos hidratados g-1. Los valores de ambos parámetros presentaron diferencias interanuales. La frecuencia reproductiva, determinada mediante el uso de los porcentajes de hembras con folículos post ovulatorios, fue de 58,5% durante enero de 2011, lo que indica que los desoves ocurren una vez cada 1-2 días. Los resultados hallados indican que el besugo se caracteriza por presentar una edad de primera madurez baja (entre 1 y 2 años), desoves parciales casi diarios pero en un período de tiempo acotado. Este tipo de estrategia podría explicar tasas de recuperación o de crecimiento poblacional (r) altas como así también la ampliación de su área de distribución o la colonización de nuevas áreas.(AU)

Genetic parameters in female reproductive traits of Nile tilapia (Oreochromis niloticus)

ABSTRACT Genetic parameters for reproductive traits in female Nile tilapia were estimated in this study using Bayesian inference method. The data set presented information from 451 Nile tilapia females that were evaluated at two different places in Maringá - Paraná - Brazil (hapas of 1 and 10 m³) and at one location in Alfenas - Minas Gerais - Brazil. A spawning examination was conducted once a week from October 2012 to March 2013 for a total of 23 weeks of evaluation. Single-trait analyses for spawning success, multiple spawning, spawning frequency, and volume of eggs/female were performed by using the software MTGSAM Threshold. The heritability estimates were 0.14, 0.16, 0.53, and 0.08 for spawning success, multiple spawning, spawning frequency and volume of eggs/female, respectively, indicating it is possible to achieve a substantial genetic gain using these reproductive traits as selection criteria.

Reproductive potential of Pagrus pagrus (Perciformes: Sparidae) in coastal waters of Buenos Aires Province (Argentina) and Uruguay (34º-39ºS)

The reproductive potential of red porgy in coastal waters of Buenos Aires Province (Argentina) and Uruguay (34º-39ºS) was studied by means of a macroscopic and histological analysis of the gonads. Length and age at first maturity were determined, and fecundity, spawning frequency and egg quality were estimated. The spawning season extended from spring through summer between October and January with a peak of spawning in December. Length and age at maturity for sexes combined was 24.5 cm TL and 1.54 years, respectively. Batch fecundity ranged from 6,974 (25 cm TL) to 110,725 (39 cm TL) hydrated oocytes and showed significant linear relationships with total length and ovary-free weight. Relative fecundity ranged from 16 to 172 oocytes per female gram (ovary free). Spawning frequency was 58.5% during January 2011, indicating that females spawned once every 1-2 days at the peak of the spawning season. The life history of red porgy in Argentina and Uruguay was characterized by a young age at first maturity and partial, almost daily, spawning in a bounded time period, a life history strategy that would facilitate population expansion or colonization of new areas, and high population recovery rates or growth (r).

Se analizó el potencial reproductivo del besugo en aguas costeras de la provincia de Buenos Aires (Argentina) y Uruguay sobre la base del análisis macroscópico e histológico de las gónadas. Se determinó la talla y edad de primera madurez sexual y se estimaron la fecundidad, frecuencia de puesta y calidad ovocitaria. Se pudo establecer que la actividad reproductiva del besugo acontece durante primavera-verano, entre octubre y enero, con un pico de desove principal en diciembre. La estimación de la talla y edad de primera madurez para ambos sexos fue de 24,5 cm LT y 1,54 años respectivamente. La fecundidad parcial presentó un ajuste lineal con la talla y el peso de la hembra y varió entre 6.974 (25 cm LT) y 110.725 (39 cm LT) ovocitos hidratados. La fecundidad relativa osciló entre 16 y 172 ovocitos hidratados g-1. Los valores de ambos parámetros presentaron diferencias interanuales. La frecuencia reproductiva, determinada mediante el uso de los porcentajes de hembras con folículos post ovulatorios, fue de 58,5% durante enero de 2011, lo que indica que los desoves ocurren una vez cada 1-2 días. Los resultados hallados indican que el besugo se caracteriza por presentar una edad de primera madurez baja (entre 1 y 2 años), desoves parciales casi diarios pero en un período de tiempo acotado. Este tipo de estrategia podría explicar tasas de recuperación o de crecimiento poblacional (r) altas como así también la ampliación de su área de distribución o la colonización de nuevas áreas.

Condición fisiológica de una población de Arca zebra (Bivalvia: Arcidae) del banco de Chacopata, Sucre, Venezuela / Physiological condition of an Arca zebra (Bivalvia: Arcidae) population from Chacopata, Sucre, Venezuela

ResumenLos índices de condición en sus diferentes versiones reflejan el desempeño del organismo en su ambiente, así como la condición somática, el valor nutritivo, la importancia comercial, el papel ecológico, y periodos de engorde. En este estudio se evaluaron diferentes índices fisiológicos, con la finalidad de conocer el estado de la población de Arca zebra y proponer estrategias de explotación y conservación con fines de consumo del recurso. Se recolectaron un total de 240 ejemplares entre julio 2010-julio 2011, en el banco de Chacopata. Mensualmente se midió la longitud total, altura y grosor de la concha. Los tejidos blandos fueron deshidratados para obtener la masa seca total. Se analizaron diferentes índices de condición: los basados en la masa del organismo, los que combinan masa y longitud de la concha, índice gonadal, índice muscular, rendimiento de la carne, la masa fresca de los tejidos blandos en relación a la longitud total y la masa seca de los tejidos blandos en relación a la longitud total. El modelo de crecimiento fue alométrico positivo entre la longitud-masa seca total. El peso de la gónada ejerció una marcada influencia sobre el índice de condición, índice gonadosmático y rendimiento.La población estuvo conformada por 82 machos y 158 hembras. Los incrementos de la masa de los tejidos blandos fueron proporcionales a las dimensiones de la concha. Se propone el índice que contrasta la masa fresca de los tejidos blandos en relación a la longitud total, como una herramienta que le permitiría a los pescadores a estimar la dinámica de la población de A. zebra, la cual ayudaría a ejercer una pesquería sustentable en el tiempo, mientras se mantengan los cánones de extracción.

Abstract:Condition indices reflect the performance of an organism in their environment, as well as their somatic condition, nutritional value, commercial importance, the ecological role and fattening periods. In this study, different physiological indices were evaluated in order to know the Arca zebra population status, and to suggest operation and sustainability strategies for this resource use and consumption. A total of 240 samples (82 males and 158 females) were collected between July 2010 and July 2011, from the Chacopata bank site. Bivalve biometric measurements were made monthly and considered: total shell length, height and width; besides, soft tissues were dehydrated to obtain total dry mass. Different condition indices were analyzed based on the body mass, or on the combination of mass and shell length: gonadal index, muscle index, meat yield, the fresh mass of soft tissue in relation to the total length, and dry mass of soft tissue relative to the total length. We found the model with positive allometric growth between the length-total dry mass. The gonadal weight exerted a marked influence on the condition index, gonadosomatic index and meat yield. Increases in soft tissue mass were proportional to the dimensions of the shell. The index contrasts fresh mass of soft tissue in relation to the total length, as a tool that would allow fishers to estimate the population dynamics of A. zebra, and to practice a sustainable fishery over time, while keeping the extraction canons. Rev. Biol. Trop. 64 (3): 1345-1352. Epub 2016 September 01.