Relationships between fish and otolith dimensions of Pomatomus saltatrix (Linnaeus, 1766) (Perciformes: Pomatomidae) in southeastern Brazil

The bluefish, Pomatomus saltatrix (Linnaeus, 1766), was used as a species-specific model to study morphometric relationships between otolith size and relative growth variables. Length-weight relationships between Otolith (Length-OL, Height-OH, and Weight-OW) and fish measurements (Total Length-TL and Total Weight-TW) were determined for fishes captured monthly during the year 2015 off the southeastern coast of Brazil. The ANCOVA and Kruskal-Wallis analysis did not indicate significant differences in the relative growth constants between sexes and length frequency distributions (p > 0.05). The condition factor also did not present significant differences between sexes, and right and left otolith measurements (p > 0.05). A total of 398 specimens were sampled: TL = 43.6-67.0 cm, TW = 365-2400 g, OL = 9.65-15.25 mm, OH = 3.65 - 5.45 mm and OW = 0.03-0.11 g. The LWR for grouped sexes was TW = 0.050TL2.55 and otoliths OW = 6.17E-05OL2.59. The best adjustments were TL vs OL (r2 = 0.90); OL vs OW (r2 = 0.90); TW vs OW (r2 = 0.81); and TW vs OL (r2 = 0.80). These results showed that such relationships are helpful tools for predicting the fish size and weight from otoliths, which may be used in food habits and paleontology studies, and other fisheries management applications.(AU)

A anchova, Pomatomus saltatrix (Linnaeus, 1766), foi usada como modelo espécie-específico de relações morfométricas de otólitos e variáveis de crescimento relativo. As relações peso-comprimento entre otólito (comprimento-CO, altura-AO e peso-PO) e tamanho do peixe (comprimento total-CT e peso total-PT) foram determinadas para indivíduos capturados mensalmente durante o ano de 2015 na costa sudeste do Brasil. As análises de ANCOVA e Kruskal-Wallis não indicaram diferenças significativas para as constantes de crescimento relativo entre os sexos e distribuições de frequência de comprimento (p> 0,05). O fator de condição também não apresentou diferenças significativas entre os sexos, e medidas do otólito direito e esquerdo (p > 0,05). Um total de 398 espécimes foram amostrados: CT = 43,6-67,0 cm e PT = 365-2400 g. A RPC para peixes foi PT = 0.050CT2,55 e para os seus otólitos foi PO = 6.17E-05CO2,59, CO = 9.65-15.25 mm, AO = 3.65 - 5.45 mm and PO = 0.03-0.11 g. Os melhores ajustes foram observados para CT vs CO (r2 = 0,90); CO vs PO (r2 = 0,90); PT vs PO (r2= 0,81) e PT vs CO (r2 = 0,80). Os resultados mostraram que essas relações são ferramentas úteis na geração de estimativas de tamanho e peso dos peixes a partir dos otólitos, permitindo a sua aplicação em estudos em outras áreas, incluindo hábitos alimentares, paleontologia e manejo da pesca.(AU)

The sagittal otolith morphology observations of sturgeon species in Iranian waters of the Caspian Sea / Observaciones sobre la morfologia de otolitos sagitales de varias especies de esturion en las aguas iranies del Mar Caspio

The morphology of the sagittal otolith of Great sturgeon (Huso huso), Persian sturgeon (Acipenser persicus) and starry sturgeon (Acipenser stellatus) species from the Iranian waters of the Caspian Sea were studied. Three otolith measurements and three shape indices were recorded from 90 sturgeon specimens. Fish biometry traits were measured and relationship between sagittal otolith length (OL)-total length (TL), and sagittal otolith weight (WO)-body weight of fish (BW) were estimated. Sagittal otolith has a triangle shape with irregular edges in great sturgeon, elongate triangle with smooth surfaces in Persian sturgeon, and relatively circular with smooth surface in starry sturgeon. The ratio of the WO/BW in starry sturgeon was significantly higher ( P <0.05) than great sturgeon and Persian sturgeon. There is a direct proportional relationship between BW and WO in Persian sturgeon (r2=0.7), great sturgeon (r2=0.9) and starry sturgeon (r2=0.9). Regression line slope for these relationships in starry sturgeon were less than Persian sturgeon and great sturgeon. Furtheremore, there is significant linear regression between OL-TL. Results showed that it is possible to identify Caspian sturgeon species based on body morphometry and sagittal otolith characteristics.

Se estudió la morfología del otolito sagital del gran esturión (Huso huso), el esturión persa (Acipenser persicus) y el esturión estrellado (Acipenser stellatus) de las aguas iraníes del Mar Caspio. Se registraron tres mediciones de otolitos y tres índices de forma, de 90 especímenes de esturión. Se midieron los rasgos de la biometría de los peces y se estimó la relación entre la longitud del otolito sagital (LO) - longitud total (LT) y el peso del otolito (PO) - peso del cuerpo de los peces (PC). El otolito sagital tiene forma de triángulo con márgenes irregulares en el gran estu- rión (Huso huso), triángulo alargado con superficies lisas en estu- rión persa y relativamente circular con superficie lisa en esturión estrellado. La relación del PO / PC en el esturión estrellado fue significativamente mayor (P <0.05) que el gran esturión y el estu- rión persa. Existe una relación directamente proporcional entre PC y PO en el esturión persa (r2 = 0.7), el gran esturión (r2 = 0.9) y el esturión estrellado (r2 = 0.9). La pendiente de la línea de regresión para estas relaciones en el esturión estrellado fue menor que el esturión persa y el gran esturión. Por otra parte, existe una regresión lineal significativa entre LO-LT. Los resultados mostraron que es posible identificar especies de esturión del Caspio basadas en la morfometría corporal y las características del otolito sagital.

Age and growth of the Amazonian migratory catfish Brachyplatystoma rousseauxii in the Madeira River basin before the construction of dams

The goliath catfish Brachyplatystoma rousseauxii has crucial economical and ecological functions in the Amazon basin. Although its life history characteristics have been studied in the Amazon, there is little information in the Madeira River basin, which holds genetically distinct populations and where dams were recently built. Using fish collected in Bolivia, Brazil and Peru, this study provides a validation of growth rings deposition and details the growth patterns of B. rousseauxii in the Madeira before the dams' construction. Age structure and growth parameters were determined from 497 otolith readings. The species exhibits two growth rings per year and sampled fish were between 0 and 16 years old. In the Brazilian portion of the basin, mainly young individuals below 5 years old were found, whereas older fish (> 5 years) were caught only in the Bolivian and Peruvian stretches, indicating that after migrating upstream to reproduce, adults remain in the headwaters of the Madeira River. Comparing with previous publications, B. rousseauxii had a slower growth and 20 cm lower maximum standard length in the Madeira River than in the Amazon River. This study provides a baseline for future evaluation of changes in population dynamics of the species following dams closure.(AU)

Brachyplatystoma rousseauxii é um bagre de importante papel econômico e ecológico na bacia amazônica. Embora existam estudos acerca de sua história de vida na Amazônia, há pouca informação para a bacia do rio Madeira, onde existem populações geneticamente distintas e recentemente foram construídas duas usinas hidrelétricas. Este estudo validou a deposição das marcas de crescimento e detalhou os padrões de desenvolvimento dessa espécie no rio Madeira, antes da construção das barragens. As coletas abrangeram os territórios brasileiro, boliviano e peruano, com estrutura etária e parâmetros de crescimento determinados a partir de 497 otólitos. Foram observadas duas marcas de crescimento por ano e indivíduos entre 0 e 16 anos. Na porção brasileira foram encontrados principalmente jovens menores de 5 anos, enquanto que os peixes mais velhos (> 5 anos) foram capturados apenas na Bolívia e Peru, indicando que após a migração reprodutiva, os adultos permanecem nas cabeceiras do rio Madeira. Comparando com estudos prévios realizados na calha principal do rio Amazonas, B. rousseauxii apresentou crescimento mais lento e comprimento padrão máximo inferior de 20 cm no rio Madeira. Este estudo fornece uma base para a avaliação futura das mudanças na dinâmica populacional desse espécie após o implementação das barragens.(AU)

Otolith morphometry provides length and weight predictions and insights about capture sites of Prochilodus lineatus (Characiformes: Prochilodontidae)

Here we choose the sábalo Prochilodus lineatus, to answer the following questions: How the otolith length and weight are correlated to fish measurements (length and weight)? How reliable are the otoliths measurements to predict the length and age of P. lineatus? Finally, we propose predictive equations of the length and weight of the fish using length and weight of the otolith. The otoliths were sampled from individuals collected in the Upper Paraná River floodplain during 2012 and 2013 years. The relationships among the otolith measurements and both length and weight of the fish were performed using linear regressions. To test whether the length and weight of the otolith differ between the sampled sites, Variance Analysis was performed. Finally, we made analysis of Kruskal-Wallis to verify if the measurements obtained through the otoliths could be used to distinguish the age of the fish. We demonstrate that the length and weight of the otolith are good proxies to predict the length and weight of the fish. Although some ages were statistically different, this result does not support the idea that the age of the fish can be accurately inferred only using otolith measures.(AU)

Neste trabalho o curimba Prochilodus lineatus foi utilizado para responder as seguintes questões: Como o comprimento e o peso dos otólitos são correlacionados com o comprimento e o peso do peixe? Até que ponto as medidas dos otólitos são confiáveis para predizer a idade do P. lineatus? Finalmente, nós propomos equações preditivas do comprimento e peso do peixe utilizando o comprimento e o peso do otólito. Os otólitos foram amostrados de indivíduos coletados na planície de inundação do alto rio Paraná durante os anos de 2012 e 2013. As relações entre as medidas dos otólitos e o peso e comprimento do peixe foram verificadas utilizando regressões lineares. Para testar se o comprimento e o peso do otólito diferem entre locais foram utilizadas Análises de Variância e para testar se as medidas dos otólitos são suficientes para distinguir as idades foram utilizados testes de Kruskal-Wallis. Nós demonstramos que o comprimento e o peso do otólito são bons preditores do comprimento e peso do peixe. Embora algumas idades foram estatisticamente diferentes entre as medidas dos otólitos, esse resultado não suporta a ideia de que a idade do peixe pode ser inferida de forma acurada somente utilizando as medidas dos otólitos.(AU)

Morphological variations of the three otoliths of some species of the family Loricariidae (Ostariophysi: Siluriformes)

Otoliths are three pairs of calcareous structures found in the inner ear of bony fish. In many cases they display a species-specific morphology. The present study describes morphological variations of otoliths, namely lapillus, asteriscus and sagitta, of eleven species belonging to four loricariid subfamilies. Otolith structures that characterize the Loricariidae and some of its subfamilies are presented. The sagitta exhibit a specific morphology that is not found in other siluriform families; it is claviform with a tapered posterior region and a flared anterior one. In the latter, central elevations are observed and the dorsal wings are continuous with lateral expansions named basal wings. Hypoptopomatinae and Loricariinae as well as Hypostominae and Ancistrinae can be grouped by two morphological patterns of the lapillus: An ovoid pattern, in which the lapillae are elongated in its supero-inferior axis and the mond hardly exceed the anterior edge of the otolith and, an oval pattern, where the lapillae are elongated in their antero-posterior axis and the mond always exceeds the anterior edge in an obvious way. The patterns proposed here could be diagnostic of certain subfamilies.(AU)

Los otolitos son tres pares de estructuras calcáreas que se encuentran en el oído interno de los peces óseos. En muchos casos ellos muestran una morfología específica para cada especie. El presente estudio describe las variaciones morfológicas de los otolitos, lapillus, asteriscus y sagitta, de once especies pertenecientes a cuatro subfamilias de loricáridos. Se presentan estructuras que caracterizan los otolitos de Loricariidae y a algunas de sus subfamilias. El sagitta exhibe una morfología específica que no se encuentra en otras familias siluriformes: es claviforme con una región posterior cónica y una anterior ensanchada. En esta última, se observan elevaciones centrales; las alas dorsales que se continuan con expansiones laterales denominadas alas basales. Hypoptopomatinae y Loricariinae, así como las subfamilias Hypostominae y Ancistrinae se pueden agrupar por dos patrones morfológicos de la lapillus: Un patrón de forma ovoide, en el que los lapillae son alargados en su eje superior-inferior y el mond difícilmente sobrepasa el borde anterior de los otolitos. El otro es un patrón oval, donde los lapillae son alargados en su eje antero-posterior y el mond siempre sobrepasa el borde anterior de una manera notoria. Los patrones propuestos aquí podrían ser diagnósticos de ciertas subfamilias.(AU)

Sagittal otolith morphology of sharpsnout seabream Diplodus puntazzo (Walbaum, 1792) in the Aegean Sea / Morfología de los otolitos sagitales del sargo picudo Diplodus puntazzo (Walbaum, 1792) en el Mar Egeo

The morphology, biometry and shape indices of the left and right sagittal otoliths were studied for sharpsnout seabream, Diplodus puntazzo species from Aegean Sea. The shape, sulcus acusticus shape, proximal and distal surfaces, anterior and posterior regions of left and right sagittal otoliths for a total of 52 D. puntazzo were analyzed. The morphometric measurements such as weight, length, width, area and perimeter were recorded for each pair of sagittal otoliths of the sharpsnout seabream. The shape indices such as form factor, roundness, aspect ratio, circularity, rectangularity, and ellipticity were calculated for left and right sagittal otoliths of D. puntazzo. The otolith width and ellipticity were significantly different (P <0.05) for left and right sagittal otolith measurements and shape indices, respectively in D. puntazzo inhabiting the Aegean Sea. Morphological characteristics of fish otoliths were highly variable in species and populations; there was limited information on the sagittal otolith morphology and shape indices. The present study provided sufficient information of the sharpsnout seabream left and right otolith morphologies, biometry, and shape indices in the Aegean Sea, they may provide a useful tool for marine and freshwater species discrimination and identification in further investigations.

Los índices morfológicos, biometría y la forma de los otolitos sagitales izquierdo y derecho se estudiaron para la especie sargo picudo, Diplodus puntazzo del mar Egeo. Se analizaron en 52 D. puntazzo la forma del surco acústico, las superficies proximal y distal y las regiones posteriores de los otolitos sagitales izquierdo y derecho. Además, se registraron para cada par de otolitos sagitales las mediciones morfométricas de peso, longitud, ancho y perímetro. Se calcularon en ambos otolitos sagitales los índices de forma, factor de forma, relación de aspecto, circularidad, ortogonalidad y elipticidad. En el D. puntazzo que habita en el mar Egeo, el ancho y elipticidad de los otolitos fueron significativamente diferentes (P <0,05), para las mediciones de otolitos sagitales izquierdo y derecho, respectivamente. Existen gran variabilidad en las características morfológicas de los otolitos de diferentes especies y poblaciones de peces, asimismo es limitada la información de los índices morfológicos y la forma de los otolitos sagitales. El presente estudio proporciono información suficiente sobre la morfología y biometría de los otolitos izquierdo y derecho del sargo picudo en el Mar Egeo, lo que puede proporcionar una herramienta útil para la discriminación e identificación de especies marinas de agua dulce y para nuevas investigaciones.

Otolith atlas of fish of the Sinos River / Atlas de otólitos de peixes do Rio dos Sinos

Otoliths are calcium carbonate structures located in the inner ear of fish; they are responsible for hearing and balance. The inner ear has three pairs of otoliths: the lapilli, the sagittae and the asterisci. The sagittae otoliths are the largest and their format is species-specific. Because of their composition, otoliths can resist to the digestive tract of ichthyophagous species, and they can be used as an important tool for identifying species of fish found in stomach contents. The purpose of this work is to provide a photographic guide of the sagittae otoliths of the main fish species from the Sinos River. This atlas consists of photographs of the sagittae otoliths of 36 species belonging to 15 families distributed in five orders.

Otólitos são estruturas formadas por cristais de carbonato de cálcio, localizadas no labirinto do ouvido interno dos peixes. São responsáveis pela audição e pelo equilíbrio. O ouvido interno possui três pares de otólitos, os lapilli, os sagittae e os asterisci. Os denominados sagittae são os maiores e seu formato é espécie-específico. Devido a sua composição os otólitos conseguem resistir ao trato digestivo das espécies ictiófagas, dessa maneira podem ser empregados como uma importante ferramenta para a identificação de espécies de peixes em trabalhos com conteúdos estomacais. O objetivo deste trabalho é a disponibilização de uma referência visual dos otólitos sagittae das principais espécies de peixes do Rio dos Sinos, para que possam servir de base para trabalhos com conteúdos estomacais de espécies ictiófagas. Este atlas é composto de fotografias dos otólitos sagittae de 36 espécies de 15 famílias distribuídas em cinco ordens.

Morphology and morphometric relationships of the sagitta of Diapterus auratus (Perciformes: Gerreidae) from Veracruz, Mexico

Sagittae otoliths are the most studied because of their morphological variability and size; the sagittae may also have valuable taxonomic use and for D. auratus has not yet been described. In the present study we present a morphological description of the sagitta otolith and an analysis of its correlation with various morphometric parameters. The biological material was captured with a beach seine in the coasts of Alvarado and Port of Veracruz, from November 2009 to June 2010. Sagittae were extracted, cleaned, photographed (SEM and optical), and measured. The analysis included the correlations between sagitta’s length and width, versus the fish standard length, height and weight, for a total of 449 fishes. The comparison between left and right sagitta showed no significant difference in both otolith length and width (t-tests, p<0.05) for each sex. The right otolith was used for the correlations for both males and females and the Fisher test (d.f. 161 and 143, p<0.001) showed no significant differences in the slopes and intersections between them. The otolith length vs. fish weight correlation showed a positive allometric growth in males (b=3.9754, p<0.05) and females (b=4.3168, p<0.05).

Los otolitos sagitta son los más estudiados debido a su variabilidad morfológica y a su tamaño, sin embargo, los otolitos de D. auratus no han sido estudiados hasta el momento. En el presente estudio, se muestra una descripción completa de la morfología y un análisis morfométrico de diversas medidas. El análisis incluye las relaciones entre el ancho y largo de la sagitta contra la longitud cefálica, longitud estándar, altura y peso de 449 peces. El material biológico fue capturado con un chinchorro playero en las costas de Alvarado y el Puerto de Veracruz de noviembre 2009 a junio 2010. Las sagittae fueron extraídas, limpiadas, fotografiadas (SEM y ópticas) y medidas. La comparación entre el otolito derecho e izquierdo no mostró diferencias significativas entre el ancho y largo (prueba de t, p<0.05) para cada sexo. El otolito derecho fue utilizado para las relaciones de las distintas medidas del otolito del pez y del otolito de hembras y machos; la prueba de Fisher (d.f. 161 and 143, p<0.001) no mostró diferencias significativas de las pendientes e intersecciones entre ellos. La relación longitud del otolito-peso del pez mostró un crecimiento de tipo alométrico positivo en machos (b=3.9754, p<0.05) y hembras (b=4.3168, p<0.05).

Crecimiento somático y relación ARN/ADN en estadios juveniles de Eucinostomus argenteus (Pisces: Gerreidae) en dos localidades del Caribe de Venezuela / Somatic growth and RNA/DNA rate of Eucinostomus argenteus (Pisces: Gerreidae) juveniles stages at two localities of the Venezuelan

Somatic growth and RNA/DNA rate of Eucinostomus argenteus (Pisces: Gerreidae) juveniles stages at two localities of the Venezuelan Caribbean. In order to evaluate the association among growth indices of marine fishes at early life stages, the somatic growth rate and physiological conditions of Eucinostomus argenteus were estimated at two Venezuelan North-East zones: Mochima Bay and Cariaco Gulf. The age and somatic growth rate were estimated based on daily growth increments in sagitta otoliths. The physiological conditions were evaluated with proteins concentrations and RNA/DNA rate, which were estimated by spectrofluorometric and fluorometric techniques, respectively, on muscle tissue. Juvenile standard length ranged from 9.80 to 39.20mm from 21 to 73 days of age. At all the study localities there were significant and positive correlations between age, otolith diameter and body size, and fitted to a linear regression model. The values of recent growth rate ranged from 0.178 to 0.418mm day-1, backcalculated growth rate oscillated between 0.295-0.393mm day-1, and RNA/DNA rate ranged from 1.65 to 6.97. Differences were not found between study zones, but there were differences between localities. Despite the fact that there was no correlation between juvenile´s somatic growth and RNA/DNA rates, the reported values suggesting a E. argenteus juvenile’s positive growth in their natural habitat at localities studied. Nevertheless, in some localities values that indicate poor nutritional conditions were registered, which could affect other future demographic rates as survivor and fecundity.

Con la finalidad de evaluar la asociación de índices de crecimiento en estadios tempranos de peces marinos, se estimó la tasa de crecimiento somático y las condiciones fisiológicas de Eucinostomus argenteus en dos zonas del nor-oriente venezolano: Bahía de Mochima y Golfo de Cariaco. La edad y el crecimiento fueron estimados basados en análisis de otolitos sagitta. Las condiciones fisiológicas fueron evaluadas por medio de las concentraciones de proteínas y la relación ARN/ADN, empleando técnicas espectofotométricas y fluorométricas sobre tejido muscular. Las relaciones entre tallas con la edad y el diámetro de los otolitos resultaron positivas, significativas y ajustadas a un modelo de regresión lineal. Los valores de la tasa de crecimiento reciente oscilaron entre 0.178 y 0.418mm día-1, la tasa de crecimiento retrocalculado varió entre 0.295 y 0.393mm día-1, y la tasa ARN/ADN osciló entre 1.65 y 6.97. No se registraron diferencias entre las zonas de estudio, sin embargo se reportaron diferencias entre localidades. A pesar de no encontrarse correlación entre la tasa de crecimiento y la relación ARN/ADN, los valores reportados sugieren crecimiento positivo de los individuos silvestres en las localidades evaluadas. No obstante, ciertas localidades mostraron valores que indican pobres condiciones nutricionales, pudiendo afectarse a futuro otras tasas vitales.

Age and growth of Spanish mackerel (Scomberomorus brasiliensis) off the northeastern coast of Brazil

Age and growth of the Spanish mackerel (Scomberomorus brasiliensis) caught off northeastern Brazil were determined. A total of 831 otoliths were examined - 296 from males (12 - 75 cm FL), 212 from females (11.5 - 72 cm FL) and 323 from specimens of undetermined sex (12.4 - 75 cm FL). There was a high percentage of juveniles in the catches, resulting mainly from the use of gillnets. Marginal increment analysis of the otoliths indicated that the shortest distances from the last ring to the edge occurred from November to May, laying down just one ring annually. One to eight rings were found, with specimen lengths ranging from 11.5 to 75.8 cm. The Schunute model was used to determine what model was best fit the data, demonstrating that the specialized von Bertalanffy growth equation is the most appropriate. Curves were established for males (L∞ = 79.52 cm, K = 0.189, t0 = -0.384 year) and females (L∞ = 109.18 cm, K = 0.114, t0 = -0.414 year), which resulted in distinct growth patterns between sexes. Based on the parameters estimated for the sexes separately, males have an approximate longevity of 15.5 years, whereas female longevity is 25.9 years. Specimens between 2 and 6 years of age represented 86 percent (n = 5,290) of the catch composition, characterizing the species as a catchable stock in the region. The present study updates essential information for assessing the stock of this important resource, for which the last growth studies in the region were carried out approximately thirty years ago.(AU)

Foram determinados a idade e o crescimento da serra (Scomberomorus brasiliensis) capturada na região nordeste do Brasil. Um total de 831 otólitos foi examinado, sendo 296 machos (12 - 75 cm FL), 212 fêmeas (11,5 - 72 cm FL) e 323 exemplares com sexo indeterminado (12,4 - 75 cm FL). Um alto percentual de exemplares jovens foi verificado nas capturas, principalmente pela utilização de redes de emalhar. A análise do incremento marginal nos otólitos indicou que as menores distâncias do último anel a borda ocorrem nos meses de novembro a maio, marcando apenas um anel anualmente. Foram encontrados de 1 a 8 anéis, com comprimentos de 11,5 a 75,8 cm FL. O modelo de Schunute foi utilizado, a fim de verificar qual modelo melhor se ajustava aos dados, demonstrando que a equação de crescimento de von Bertalanffy especializada é a mais indicada. Curvas foram estabelecidas para machos (L∞ = 79,52 cm, K = 0,189, t0 = -0,384) e fêmeas (L∞ = 109,18 cm, K = 0,114 e t0 = -0,414), resultando em um padrão distinto de crescimento entre sexos. De acordo com os parâmetros estimados para sexos separadamente, machos apresentam longevidade aproximada de 15,5 anos e fêmeas de 25,9 anos. Exemplares entre 2 e 6 anos de idade representaram 86 por cento (n = 5.290) da composição das capturas, caracterizando o estoque capturável da espécie na região. O presente estudo atualiza informações essenciais para avaliação do estado de exploração desse importante recurso, cujo último estudo de crescimento na região foi realizado aproximadamente há 30 anos atrás.(AU)

Linking larval history to juvenile demography in the bicolor damselfish Stegastes partitus (Perciformes: Pomacentridae)

Otolith-based reconstructions of daily larval growth increments were used to examine the effect of variation in larval growth on size and age at settlement and post-settlement growth, survival and habitat preferences of juvenile bicolor damselfish (Stegastes partitus Poey). During August 1992 and 1994, newly settled S. partitus were collected from Montastraea coral heads and Porites rubble piles in Tague Bay, St. Croix, U.S. Virgin Islands (17 degrees 45'N, 64 degres 42' W). Daily lapillar otolith increments from each fish were counted and measured with Optimas image analysis software. S. partitus pelagic larval duration was 23.7 d in 1992 (n = 70) and 24.6 d in 1994 (n = 38) and larval age at settlement averaged 13.0 mm total length both years. Analysis of daily otolith increments demonstrated that variation in larval growth rates and size and age at settlement had no detectable effect on post-settlement survivorship but that larger larvae showed a preference for Montastraea coral at settlement. Late larval and early juvenile growth rates showed a significant positive relationship indicating that growth patterns established during the planktonic stage can span metamorphosis and continue into the benthic juvenile phase. Larval growth rates during the first two weeks post-hatching also had a strong effect on age to developmental competence (ability to undergo metamorphosis) in both 1992 and 1994 with the fastest growing larvae being 8 d younger and 0.8 mm smaller at settlement than the slowest growing larvae. These differential growth rates in early stage larvae established trajectories toward larval developmental competence and may prove important in biogeographical studies of larval dispersal

Verificación de la marca de eclosión en los otolitos sagitales de larvas de Sardinella aurita (Pisces: Clupeidae) / Verification of the eclossion mark in the sagittal otolith of larvae from the Sardinella aurita (Pisces: Clupeidae)

The study of otolith in larvae is important to determine fish age and growth, essential parameters in the study and management of fisheries resources. In this study, the formation of the hatching mark in Sardinella aurita was verified on ichthyoplankton samples collected off southern Cubagua island, Venezuela, from May 1998 to January 1999. The embryos were kept alive using a culture system until they hatched and daily a group of 10 to 30 larvae were fixed in 95% ethanol. An image analysis system was used to measure morphometric characteristics of larvae and sagittal otoliths. Following are mean values in newly hatched larvae: otolith hatching mark distance from nucleus 4.78 m (I.C. 0.36 m, p 0.05 n = 30), increase width 1.46 m (I.C. 0.17 microm, p 0.05, n = 30) and diameter 14.28 m (IC 1.11 m, p 0.05, n = 30). The mean standard length of larvae at age 0 was 3.31 mm (I.C. 0.08 mm, p 0.05, n = 200). The identification of the hatching mark allows the exact calculation of the number of rings in larvae from the natural environment.