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The anadromous catfish, Genidens barbus, is a commercial and vulnerable species from South America. The aims of the present study were to assess whether the nursery areas can be discriminated by using microchemical signatures of lapillus otoliths, to assess the accuracy of classifying fish in relation to natal nursery area and to discuss the possibility of existence of homing behaviour. Thus, the otolith-core chemical signatures (barium (Ba):calcium (Ca), lithium (Li):Ca, magnesium (Mg):Ca, manganese (Mn):Ca, strontium (Sr):Ca, and zinc (Zn):Ca ratios) of adult fish were compared among different estuaries (De La Plata River in Argentina, and Patos Lagoon, Paranaguá Bay and Guanabara Bay in Brazil). PERMANOVA analysis showed significant differences in the multi-element signatures of the otolith core among sampling sites for all cohorts (2002, 2003, 2006 and 2007), indicating that the technique has considerable potential for use in future assessments of population connectivity and nursery areas of G. barbus. Via quadratic discriminant function analysis, fish were classified to natal nursery areas with 80–100% cross-validation classification accuracies. These results suggested that a high level of spatial segregation exists in adult catfish life and homing behaviour could not be ruled out on the basis of our data.

The purpose of this paper is to assess the use of multi-elemental otolith fingerprints as a tool to delimit catfish Genidens barbus fish stocks in four estuaries from the southwestern Atlantic Ocean. Barium:Calcium (Ca), Magnesium:Ca, Manganese:Ca, Sodium:Ca and Strontium:Ca ratios in the otolith edge were determined by LA-ICPMS. PERMANOVA analysis reveal significant differences in the multi-element signatures among estuaries (p=0.0001-0.002). Reclassification rates of quadratic discriminant analysis are high, averaging 89.9 % (78-100%). The new data presented here show that the otolith chemistry is a potential tool for stock identification, and indicates the presence of at least four stocks which should probably be handled independently.

Specimens of Brazilian silverside (Atherinella brasiliensis,We present some considerations with regard to the general methodology for adjusting weight-length relationships.

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This study aimed to verify variations in the form of the sagitta otolith of Menticirrhus americanus as to their ontogeny, sex and stage of such structure. Ontogenetically were found significant differences (p < 0.05) for all shape indices (aspect ratios, shape factor, rectangularity, ellipticity, relative surface of sulcus acusticus) and also in the wavelet of the otolith. The CVA presented a 98.6% correct reclassification of the otolith between interval class. Sexual variations were found in the wavelet and in the relative surface of sulcus acusticus index. Between adult females and young females, differences were not detected in the wavelet and rectangularity, but significant differences were found in all other shape indices. The CVA presented a 79.6% correct reclassification of the otolith of the sexes and stages of life sampled. Young females and adults females showed highest correct percentage of classification. The results of this study demonstrate for the first time the influence of the ontogenetic variation and sexual in the form of the otoliths.

Summary:In order to characterize the ontogeny of Anchoa tricolor, the morphology and morphometry of sagitta otoliths were described. A total of 397 pairs of sagitta otoliths of A. tricolor (20 to 85 mm) were measured and analysed by means of digital images. Morphological description was done in terms of shape and features. The Huxley model was fitted to otolith length against total length (TL) and weight (TW), and residual analyses were done in order to detect the polyphasic growth. Six shape indices were calculated (otolith height/otolith length and otolith length/total length aspect ratios, rectangularity, roundness, relative sulcus surface and rostrum index) and after size effect removal, they were analysed in terms of TL. The results of these analyses allowed three distinct growth phases to be identified: (1) up to 40 mm TL and related to low swimming ability; (2) between 41 and 60-70 mm TL, when fish displacements increase but the first maturation has not yet occurred; and (3) after 71 mm TL, when fish become adults. Landmarks and semi-landmarks were used to analyse relative warps during the otolith development. The MANOVA analysis between the centroid size and class intervals showed significant differences in the interaction of all classes except between 71-80 and 81-90 mm.Keywords: shape index; geometric; morphometry; Engraulidae; Brazil; description.Desarrollo ontogénico del otolito sagitta de la anchoa, Anchoa tricolor, en un estuario subtropical Resumen: Se describen la morfología y morfometría de los otolitos sagitta de Anchoa tricolor con el objetivo de caracterizar su ontogenia. Se midieron un total de 397 pares de otolitos sagitta de A. tricolor (20 a 85 mm) y se analizaron por medio de imágenes digitales. La descripción morfológica se hizo en términos de forma y características. Se ajustó el modelo de Huxley a la relación longitud del otolito, longitud total (TL) y peso (TW), respectivamente, y se realizaron análisis de residuos para detectar el crecimiento polifásico. Se calcularon seis índices de forma (OH/OL y OL/LT radios de aspecto, rectangularidad, redondez, superficie relativa del sulcus e índice de rostrum) y, una vez eliminado el efecto de talla, se analizaron en términos de longitud total. Los resultados de estos análisis permitieron identificar tres fases distintas de crecimiento: (1) una fase inicial, hasta 40 mm TL y relacionada con una habilidad natatoria baja; (2) entre 41 y 60-70 mm TL, cuando los desplazamientos del pez aumentan, pero aún no se ha producido la primera madurez y (3) superior a 71 mm TL, cuando el pez es ya adulto. Se utilizaron puntos homólogos y puntos equidistantes para analizar deformaciones relativas durante el desarrollo del otolito. El análisis MANOVA entre el tamaño del centroide y los intervalos de clases de talla mostraron diferencias significativas en la interacción de todas las clases, excepto entre 71-80 y 81-90 mm.Palabras clave: índice de forma; geometría; morfometría; Engraulidae; Brasil; descripción.