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Hemisorubim platyrhynchos: A More Manageable Shovelnose Catfish. Author: Seth Gibson. GIBS Photographer: Aaron Norman. Monster cats can reach several . Braz J Biol. Nov;64(4) Epub Mar 2. Age and growth of the porthole shovelnose catfish (Hemisorubim platyrhynchos) in the Pantanal. Hemisorubim platyrhynchos is a medium- to large-sized pimelodid catfish distributed along several river basins of the Neotropical Region.

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Age and hemisofubim of the porthole shovelnose catfish Hemisorubim platyrhynchos in the Pantanal. Idade e crescimento do jurupoca Hemisorubim platyrhynchos no Pantanal. I ; Mateus, L. II ; Barbieri, G. The Porthole Shovelnose Catfish, Hemisorubim platyrhynchosis the sixth largest pimelodidae of the Pantanal.

The fish, which came from commercial and experimental fisheries, were all caught with hook and line. Nevertheless, decrease in the marginal increment index occurring as waters recede suggests this as the probable time when growth rings form. Individual life span was estimated at The results suggest that fork length is a good predictor of age platyrhyncho individuals of this species. Os platyrhynchoe provieram da pesca comercial e experimental com linha e anzol.

The genus Hemisorubim is a monospecific member of the Pimelodidae family. The meat of H.

In the southern Pantanal, landing data, including professional and recreational fishing results platyrhynchossrecorded 7. The accumulated amount of fish landed from to was 50 tons Catella, Despite its wide distribution, average abundance, and importance in ecosystem functioning and regional fishery, little is known about the biology of this species.

Age and growth of the porthole shovelnose catfish (Hemisorubim platyrhynchos) in the Pantanal.

We report here on the age and growth of H. The purpose of this study was to determine the age, adjust the von Bertalanffy growth curve, and estimate the longevity of individuals of the species.

Sampling procedure and data analysis.

The platyrhynchoa of jurupoca specimens were recorded between July and October During the period of legally prohibited fishing between November and February44 additional specimens were collected for research purposes. Additional information about the study area is given in Penha and Penha et al.

Additional details about fin-spine preparation, measurements, ring-reading conditions, and criteria used to identify double and false hemisorrubim can be found in Penha and Penha et al. To circumvent the problem created by the reabsorption of the first growth ring Casselman,an ANOVA was performed. The Von Bertalanffy growth model Bertalanffy, was adjusted to the age data. Growth curve parameters were used to estimate longevity of the individuals in stock by the Taylor method Taylor, Details about data analyses can be found in Penha and Penha et al.

The results indicated that the pectoral fin-spines of H. In some cases, sections revealed grooves crossing the rings. In some cases, rapid growth zones were more translucent. However, even in such cases the growth rings were clearly visible. Whereas double marks usually appeared between the first and second rings, false marks were common between the second and fifth rings. Thus, only data from the readings of these fin-spines were considered reliable and used in th subsequent analyses.


The sample used in this study included individuals with FL varying from 26 to 64 cm. The mean size FL mean of the sampled individuals was The fin-spine sections revealed up to 7 rings, representing 7 age groups, with the age class with 3 rings predominating Fig. The mean age t mean was 2. Because of the limited number of observations, which would lead to a significantly imbalanced analysis and reduce the power of the F test, the ANOVA test was conducted excluding age 7.

This increased the reliability of the readings taken from fin-spine rings. Analyses platyrrhynchos the relation between the number of rings, fin-spine size, and FL showed that platyrhynchls spine rings were indicators of the fish’s growth. A visual analysis of the box plot between the fin radius and ring number indicated that the larger spines contained more rings Fig. Moreover, a positive relation was found between lengths of fin and finspine.

Age and growth of the porthole shovelnose catfish (Hemisorubim platyrhynchos) in the Pantanal.

platyrhynchso Linear models satisfactorily described the relation between these variables Fig. In short, a positive relation was found between the fin-spine ring number and the size of the individuals.

The analysis of growth data along the edge of the spines marginal increment – MI by a statistical test did not determine ring-formation periodicity. Owing to the low number of observations, the test was conducted on seasonal MI of individuals having 2 or 3 rings. Although no differences between sessions were detected through the Kruskal-Wallis test, Fig.

The FL variation explained The b platydhynchos, estimated at 3. Analyses of the residual variances and coefficients of determination indicated that the relationship between the Rz and FL of the spines could be described consistently by several models r 2 of models: Hence, the simplest model, i.

Fraser-Lee’s equation, which was used to perform backcalculations, produced consistent results. As expected, the backcalculated lengths were shorter than those observed, the differences decreasing with age Table 1. The mean length reached in the cohort’s first year of life, shown in column FL 1 of Table 1decreased with the age of the cohort from which it was estimated, the only exception being the most recent cohort.

This fact suggests the presence of the Rosa-Lee phenomenon Lee,apud Ricker, The Von Bertalanffy model was adjusted both to lengths observed by age and to the backcalculated one.

Because the confidence intervals overlapped, they were considered statistically the same. The last procedure produced a life expectancy estimate longevity paltyrhynchos Hence, the individuals of the species would take Many hard structures have been used to determine the age of pimelodidae.

Among these, otoliths, vertebrae, and fin-spines are the structures that have produced the best results Fenerich et al.

Although few studies compare the age determined by various structures of the same sample, preliminary data indicate that age underestimations tend to result when based on pectoral fin-spines in comparison with those based on dorsal spines Layher, and vertebrae Clay, Even so, indirect evidence suggests that the pectoral fin-spines of H.

However, it should be noted that it was fairly difficult to identify the rings on the edge of the spine in individuals with more than five rings. This had been expected since, from the sixth growth mark on, identifying the edge rings tends to become increasingly difficult Casselman, Analysis of the relative marginal increment by the Kruskal-Wallis test did not indicate the period of growth ring formation of H.


However, the sharp decline in the MI value recorded during the receding period suggests that rings probably form during this period. This pattern differs from the one normally found for Pimelodidae inhabiting river-floodplain systems.

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Most studies undertaken so far have founded evidence of ring formation during the dry season Fenerich et al. These authors detected the formation of two annual growth rings: The growth rate reduction and consequent growth ring formation have generally been associated with temperature, environmental retraction effects during the dry season, reproduction Welcome,and migration Brett, Thus, annual growth ring formation in the species under study here appears to be associated with migration that takes place during the receding period, when the fish leave the flooded areas and return to the river channel Ferraz de Lima, Backcalculated lengths indicated the presence of the Rosa-Lee phenomenon in the analyzed sample.

When this phenomenon is present, the mean size calculated for younger fish is smaller the older the fish from which it was estimated Ricker, ; Several hypotheses have been advanced to explain this phenomenon, the main ones being: In the Pantanal, the Rosa-Lee phenomenon detected in this study probably results from fishing regulations, which determine, among other things, minimum catch sizes. Slow-growing individuals may reach this size only when they are older 3 or more rings.

Age and growth of the porthole shovelnose catfish (Hemisorubim platyrhynchos) in the Pantanal

Fish mortality platyrhyncbos therefore size-dependent, with fast-growing individuals caught before the others, which can explain the presence of the Rosa-Lee phenomenon in this study. The adjustment of the Von Bertalanffy model based on backcalculated lengths was more precise than that based on lengths observed by age. Backcalculation lessened the data noise, reducing the lengths of individuals captured along the growth period to theoretical lengths at the time of the formation of each ring.

The estimated growth parameters indicate that the species presents a relatively slow growth rate. However, first-year growth is rapid. This strategy is common to platyrhynhos Pimelodidae species of South American river-floodplain systems and may be one of the causes of the great abundance of these fish in rivers of the continent. We are grateful to an anonymous reviewer for advice and comments on hdmisorubim draft. Human Biology Journal of the Limnological Society of South Africa8: World Platyrhynchis Web eletronic publication: Progressive Fish-Culturist Fisheries Management and Ecology Pimelodidae basado en la lectura de estructuras duras espinas de aleta pectoral en el Alto Rio Meta Colombia.

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