Recepção: 30 Abril 2019
Aprovação: 18 Junho 2019
Publicado: 04 Julho 2019
Resumo: A relação peso-comprimento tem muitas funções na área da ecologia de peixes. O objetivo do presente trabalho é o de fornecer as estimativas de relações morfométricas para 13 espécies de peixes de água doce. As amostras foram coletadas com o auxílio de malhadeiras, em maio e setembro de 2015, no rio Tarumã, Reserva Biológica do Jaru. As relações peso-comprimento foram estimadas a partir de 343 espécimes pertencentes a treze espécies, sete famílias e duas ordens. As regressões lineares foram significativas (p≤0,001). O valor de b variou de 1,36 em Leporinus friderici a 3,30 em B. amazonicus. A espécie Colossoma macropomum apresentou um padrão de crescimento isométrico (b=3,09). As novas relações peso-comprimento para 2 espécies, novo peso máximo para 4 espécies e tamanhos máximos registrados para 3 espécies destacam a escassez de informações sobre aspectos biológicos dos peixes da Amazônia. Estes resultados podem fornecer informações para a FishBase, bem como dados importantes para o manejo da ictiofauna e conservação da Bacia do Rio Tarumã.
Palavras-chave: Amazônia, Reserva Biológica, Biodiversidade, Conservação, Ictiofauna.
Abstract: The length-weight relationship has many functions in the area of fish ecology. The objective of this work is to provide the estimates of morphometric relationships for 13 freshwater fish species. Samples were collected with the aid of gillnets in May and September 2015 in the Tarumã river, Jaru Biological Reserve. Length–weight relationships were estimated from 343 specimens belonging to thirteen species, seven families and two orders. The linear regressions were significant (p≤0.001). The value of b varied from 1.36 in Leporinus friderici to 3.30 in B. amazonicus. The specie Colossoma macropomum had an isometric growth pattern (b=3.09). The new Length–weight relationships for 2 species, new maximum weight for 4 species and maximum sizes recorded for 3 species highlight the scarcity of information on biological aspects of Amazon fishes. These results can provide information for the FishBase as well as important data for the management of icthyofauna and conservation of the Tarumã River Basin.
Keywords: Amazonia, biological reserve, Conservation, Biodiversity, Ichthyofauna.
The largest number of protected areas (PA) in the world is in Brazil (1), totaling more than 30000 Km2 (2). About 43% of Brazilian Amazon are considered PA (3). Although there are doubts about the purpose of conservation units, studies indicate that these are useful in reducing deforestation and ichthyofauna conservation (4,5).
The Amazon basin is home to the world's largest ichthyofauna diversity (6,7). In the Madeira River basin, more than 820 species of fish were recently identified (8). In the Machado River basin, Madeira River sub-basin, 48 species were collected at the Pirarara and Tamarupa rivers (9), 140 species in small streams (10) and 74 species in the Tarumã river, middle Machado River (11). The studies on evaluation of fish stocks in the Amazon region are scarce (12), as well as information on fish morphometric relationships (13,14).
The length-weight relationship (LWR) has many functions in the area of fish ecology (15). The LWR allows i) to predict fish length based on weight and vice versa, ii) calculate the growth rate of the species and iii) obtaining the body state of the individuals sampled (16). The LWR studies are necessary to understand the fish life cycle, especially in regions where fishing represents the important economic activities and the main animal protein consumed by traditional communities (12). The objective of this study was to calculate the LWR of 13 species of fish captured in the Tarumã River, Jaru Biological Reserve, as the first study on the biology of fish species in this PA.
MATERIALS AND METHODS
The Jaru Biological Reserve (Rebio Jaru) is administered by the Instituto Chico Mendes de Conservação da Biodiversidade (ICMBio). The Rebio Jaru hydrographic network (9°27’19” S, 61°40’43” W - 9°47’04” S, 61°40’19” W) is part of the Machado River basin, Rondônia State, Brazil. The Tarumã River is located in the Rebio Jaru area.
We performed collections of freshwater fish in May and September 2015. We collected the fish using a total of eight gillnets with meshes of 2 x 20 m (mesh sizes: 30, 40, 50, 60, 70, 80, 90 and 100 mm, opposite knots), these were euthanized in a solution of clove oil (17). The fish were fixed in 10% formalin solution, preserved in 70% ethanol and later deposited in the Coleção de Peixes da UFMT, Brazil. The fish sampling was authorized by the ICMBio (license code: 48723–2/2015).
The individuals captured were identified with the help of identification keys (8) and biometric data (total length (TL) in cm and total weight (TW) in g) were recorded. Weight and length were estimated using the expression P = aCb, where P = weight total, C = total length, a = intercept and b = angular coefficient (18); the parameters a and b were estimated after logarithmic transformation of weight and length data (19). We verified in the fishBase (20) the absence of the LWR records, as well as the occurrence of the TL and TW maximum values recorded for the species captured in the Tarumã river. Statistical tests were performed using the R-package (21) with significance of p<0.05.
The LWR was estimated from 343 specimens belonging to thirteen species, seven families and two orders (Table 1). The linear regressions were significant (p≤0.001). The R2 varied from 0.91 in Boulengerella cuvieri to 0.99 in Brycon amazonicus. The intercept a varied from 0.0045678 in B. amazonicus to 0.0798564 in B. cuvieri (mean 0.0422121±0.0532370). The value of b varied from 1.36 in Leporinus friderici to 3.30 in B. amazonicus (mean 2.33±1.37). The specie Colossoma macropomum had an isometric growth pattern (b=3.09) (Table 1).
|TL (cm)||TW (g)||Regression parameters|
|Order/Family/species||N||Min.||Max.||Min.||Max.||a||b (95% CL)||R2|
|Leporinus friderici (Bloch, 1794)||15||21.7||35.1||250.2||545.3||0.0245678||1.36 (1.23 to 1.55)||0.92|
|Brycon amazonicus (Spix & Agassiz, 1829)†||19||23.5||60.2||135||2950.2||0.0045678||3.30 (3.15 to 3.57)||0.99|
|Boulengerella cuvieri (Spix & Agassiz, 1829)||22||24.7||84.1||650.1||4035.5||0.0798564||1.85 (1.56 to 2.10)||0.91|
|Hydrolycus armatus (Jardine, 1841)||27||32.5||65.3||380.3||2501.3||0.0197435||2.95 (2,47 to 3.17)||0.92|
|Hydrolycus tatauaia Toledo-Piza, Menezes & Santos, 1999||25||28.1||35.2||481.3||839.1||0.0387431||2.80 (2.49 to 3.20)||0.96|
|Prochilodus nigricans Spix & Agassiz, 1829||23||9.5||35.2||50.1||820.0||0.0261234||2.17 (1.98 to 2.50)||0.93|
|Colossoma macropomum (Cuvier, 1816)||27||34.2||64.5||1500.0||10150.3||0.0234781||3.09 (2.87 to 3.22)||0.92|
|Myloplus lobatus (Valenciennes, 1850)†,*||24||16.0||31.2||280.2||320.3||0.0465211||2.18 (1.87 to 2.34)||0.90|
|Myloplus rubripinnis (Müller & Troschel, 1844)||28||15.4||39.2||150.2||1643.2||0.0123121||1.78 (1.55 to 2.02)||0.96|
|Myloplus torquatus (Kner, 1858)†,*,•||51||16.4||34.6||268.0||1050.0||0.0134521||3.27 (3.01 to 3.48)||0.93|
|Serrasalmus compressus Jégu, Leão & Santos, 1991†,•||30||6.5||26.3||4.5||613.2||0.0128943||3.29 (2.98 to 3.60)||0.96|
|Serrasalmus rhombeus (Linnaeus, 1766)•||52||19.0||46.4||260.0||1573.2||0.0266721||2.39 (2.03 to 2.69)||0.97|
|Ageneiosus inkermis (Linnaeus, 1766)||15||23.3||50.5||202.2||270.2||0.0387322||2.68 (2.23 to 2.87)||0.93|
The new LWRs for 2 species, new maximum weight for 4 species and maximum sizes recorded for 3 species highlight the scarcity of information on biological aspects of Amazon fishes. The allometric coefficients of the L. friderici, B. cuvieri, Prochilodus nigricans, Myloplus lobatos, Myloplus rubripinnis and Serrasalmus rhombeus species are not among the values (2.7–3.5) described by Froese (16). Factors such as habitat, area, seasonality, degree of stomach repletion, sex ratio, health, sample size, reproductive stages and preservation methods, could justify the values not in line with that proposed by Froese (16,22,23,24). These results can provide information for the FishBase as well as important data for the management of icthyofauna and conservation of the Tarumã River Basin.
Conflict of interest
There is no conflict of interest
We are grateful to the staff members of the ICMBio for their financial support and technical assistance in the fieldwork and Universidade Federal de Rondônia for their laboratory support.
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