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1.
J Fish Biol ; 93(5): 874-886, 2018 Nov.
Article in English | MEDLINE | ID: mdl-30198205

ABSTRACT

Age, growth and reproductive characteristics of six westslope cutthroat trout Oncorhynchus clarkii lewisi populations were studied in the south-western Rocky Mountains in Alberta, Canada. Sagittal otoliths were collected from 605 fish ranging in size from 36 to 250 mm (fork length). The maximum detected age (13 years for females and 12 for males) was higher than has been reported previously in published literature; but no significant differences in age distributions between males and females were found. Length growth rates, estimated using the von Bertalanffy growth function, showed that males and females had similar growth rates. Sex ratios varied between 0.3 to 2.0 females per male. Age and size at 50% maturity were greater for females than males (4.9 years and 139 mm v. 3.7 years and 125 mm). Mature females were yearly spawners with highly variable fecundities (mean ± S.D. = 223 ± 94) and their ovaries contained both developed and undeveloped eggs. Across all populations, mean instantaneous mortality rate (Z) was estimated as 0.555, annual survival rates for 0-1 year-old fish were 3.2 and 57.4% for older fish. An altitudinal distribution gradient was observed, with older fish occupying upper stream reaches. This study provides a comprehensive evaluation of biological characteristics and structure of O. c. lewisi populations inhabiting small, mountain streams and should provide useful basic information for management policies of this threatened species in eastern drainage of the Canadian Rocky Mountains.


Subject(s)
Animal Distribution/physiology , Oncorhynchus/physiology , Reproduction/physiology , Rivers , Age Factors , Animals , Canada , Female , Male , Oncorhynchus/growth & development
2.
An Acad Bras Cienc ; 90(2 suppl 1): 2097-2106, 2018 Aug.
Article in English | MEDLINE | ID: mdl-29947663

ABSTRACT

This study aimed to describe the growth parameters of Anchoa tricolor in a subtropical estuary. From August 2010 to July 2011, 10.009 specimens of the anchovy Anchoa tricolor, mean total length 4.2 cm (±1.45), were captured in the intertidal region of the Estuarine Complex of Paranaguá (25º 15' - 25° 35' S and 48° 20' - 48° 45' W). Species´s weight/length relationship for grouped genders was described as follow: W = 0.0000591.Lt3.282 (length in centimeters; weight in grams) showing a positive allometric growth pattern (b>3; P=0.000). Significant differences concerning weight/length relationship for males, females and unsexed individuals were identified. Parameters of the length to age growth curve were estimated by adjusting a von Bertalanffy growth equation from aged individuals from a length-frequency distribution: L∞ = 10.06 (1-e-17715(t + 0.205)) (length in centimeters, age in years). The age to attain 95% of the asymptotic length ( A95 ; longevity sensu Taylor) was estimated at 1.7 years. Size frequency distributions indicate that A. tricolor uses the estuarine area as reproductive and growing grounds, especially during the first year of the life cycle, where the species represent a key element for ecosystem functioning due to relatively high abundance and energy transference from plankton to top predators.

3.
An Acad Bras Cienc ; 89(3 Suppl): 2261-2272, 2017.
Article in English | MEDLINE | ID: mdl-28746552

ABSTRACT

Specimens of Brazilian silverside (Atherinella brasiliensis, n=9672) with a length range of 1.5 to 14.2 cm were captured in the intertidal areas of the Estuarine Complex of Paranaguá, Brazil, between August 2010 and July 2011. The species' weight-length relationship was represented by the equation W=0.00533 L3.136 with a slightly positive allometry (b>3) and could be divided into two growth stanzas: W = W1 + W2; Stanza 1: W1= SW. (0.005239 L3.152); Stanza 2: W2= (1 - SW). (0.000699 L3.913); Switch-Function: SW = [1 + e1.204 (L - 11.66)]-1. The breakpoint between the first and second stanza (11.66 cm) matches published values for the estimated size at first maturity of adult females. Frequency distributions indicate that the species is present in the shallow areas of the Estuarine Complex of Paranaguá during all phases of its ontogenetic development, with the recruitment of juveniles taking place between October and November. Modal displacement was monitored throughout 12 months. The von Bertalanffy growth model and longevity was estimated as follow: asymptotic length (L∞) of 17.5 cm, growth coefficient (K) of 0.89 (year-1) and longevity (A95) of 3.33 years. We present some considerations with regard to the general methodology for adjusting weight-length relationships.


Subject(s)
Body Size , Body Weight , Fishes/growth & development , Animals , Brazil , Longevity
4.
An. acad. bras. ciênc ; 89(3,supl): 2261-2272, 2017. tab, graf
Article in English | LILACS | ID: biblio-886789

ABSTRACT

ABSTRACT Specimens of Brazilian silverside (Atherinella brasiliensis, n=9672) with a length range of 1.5 to 14.2 cm were captured in the intertidal areas of the Estuarine Complex of Paranaguá, Brazil, between August 2010 and July 2011. The species' weight-length relationship was represented by the equation W=0.00533 L3.136 with a slightly positive allometry (b>3) and could be divided into two growth stanzas: W = W1 + W2; Stanza 1: W1= SW. (0.005239 L3.152); Stanza 2: W2= (1 - SW). (0.000699 L3.913); Switch-Function: SW = [1 + e1.204 (L - 11.66)]-1. The breakpoint between the first and second stanza (11.66 cm) matches published values for the estimated size at first maturity of adult females. Frequency distributions indicate that the species is present in the shallow areas of the Estuarine Complex of Paranaguá during all phases of its ontogenetic development, with the recruitment of juveniles taking place between October and November. Modal displacement was monitored throughout 12 months. The von Bertalanffy growth model and longevity was estimated as follow: asymptotic length (L∞) of 17.5 cm, growth coefficient (K) of 0.89 (year-1) and longevity (A95) of 3.33 years. We present some considerations with regard to the general methodology for adjusting weight-length relationships.


Subject(s)
Animals , Body Weight , Body Size , Fishes/growth & development , Brazil , Longevity
5.
PLoS One ; 10(5): e0125059, 2015.
Article in English | MEDLINE | ID: mdl-25996777

ABSTRACT

Understanding species linkages and energy transfer is a basic goal underlying any attempt at ecosystem analysis. Although the first food-web studies were based on gut contents of captured specimens, the assessment of stable isotopes, mainly δ13C and δ15N, has become a standard methodology for wide-range analyses in the last 30 years. Stable isotopes provide information on the trophic level of species, food-web length, and origin of organic matter ingested by consumers. In this study, we analyzed the ontogenetic variability of δ13C and δ15N obtained from samples of three Neotropical fish species: silver sardine (Lycengraulis grossidens, n=46), white lambari (Cyanocharax alburnus, n= 26), and the red-tail lambari (Astyanax fasciatus, n=23) in Pinguela Lagoon, southern Brazil. We developed a new metric, called the Weighted Isotopic Signature (φ 15N or φ 13C, ‰), that incorporates ontogenetic variability, body growth, and natural mortality into a single number.


Subject(s)
Biodiversity , Ecosystem , Fishes , Animals , Brazil , Models, Theoretical
6.
Neotrop. ichthyol ; 8(4): 835-840, 2010. graf, tab
Article in English | LILACS | ID: lil-571586

ABSTRACT

A weight/length relationship was established for Astyanax jacuhiensis (Cope, 1894) (n = 370) and Cheirodon ibicuhiensis Eigenmann, 1915 (n = 701), from samples taken monthly in Fortaleza Lagoon, Cidreira, Rio Grande do Sul, from December 1991 through November 1992. Both species showed a polyphasic allometric growth pattern, each stanza described by an independent power equation controlled by a switch function. For C. ibicuhiensis, this change in the growth pattern occurred at 2.948 cm standard length (SL), close to published sizes for the attainment of female maturity. The change in the growth pattern of A. jacuhiensis (SL = 3.481 cm) was below the predicted size at first maturity, and merits further investigation. Although not conclusive, our data suggest that a complex growth pattern is frequent in nature, and perhaps is not usually identified because trends are obscured by natural variability. Despite the increased complexity resulting from the application of a more-complex equation, the identification of a change in the growth pattern could indicate important aspects of fish biology, including the attainment of sexual maturity.


A relação peso/comprimento para Astyanax jacuhiensis (Cope, 1894) (n = 370) e Cheirodon ibicuhiensis Eigenmann, 1915 (n = 701) foi estimada a partir de amostras mensais efetuadas na lagoa Fortaleza, Cidreira, Rio Grande do Sul (dezembro de 1991 a novembro de 1992). As espécies analisadas apresentaram padrão de crescimento alométrico polifásico, sendo cada fase descrita por uma equação potência independente controlada por uma função interruptora. Para C. ibicuhiensis foi identificada uma modificação no padrão de crescimento com 2,948 cm de comprimento padrão (CP), valor próximo à dados publicados relativos ao início da maturação sexual. A alteração observada no padrão de crescimento de A. jacuhiensis (CP = 3,481 cm) encontra-se abaixo do tamanho previsto para a primeira maturação e sugere a necessidade de investigação adicional. Embora não conclusivos, nossos dados sugerem que padrões complexos de crescimento são frequentes na natureza e, talvez, não identificados porque tendências sutis acabam por ser obscurecidas pela variabilidade natural dos dados. Apesar do aumento de complexidade resultante da aplicação de uma equação complexa, a identificação de mudanças no padrão de crescimento pode apontar para aspectos relevantes da biologia de peixes, incluindo a maturação sexual.


Subject(s)
Animals , Growth/physiology , Fishes , Reproduction
7.
Neotrop. ichthyol ; 7(2): 217-222, Apr.-June 2009. graf, tab
Article in English | LILACS | ID: lil-520418

ABSTRACT

Correct estimates of size at first maturity (L50) are useful for fish stock management and different methods have been proposed. In this study we propose the use of a modified logistic to estimate L50, including a variable asymptote (A). We also test the use of the Gonadossomatic Index (GSI) as a flag to establish the reproductive status of each female fish. The method is demonstrated using GSI data for four Neotropical fish species: Characiformes: Astyanax fasciatus (n = 473) and Oligosarcus robustus (n = 297); Siluriformes: Loricariichthys anus (n = 427) and Trachelyopterus lucenai (n = 195). The results were stable enough to propose this method be used for other fish species with different life histories and with a relatively unconstrained sampling programs. Nevertheless, a wide scale test program is desirable to identify any possible bias in this approach.


Estimativas precisas do tamanho de primeira maturação (L50) são úteis para a gestão de estoques naturais, existindo diversos métodos disponíveis na literatura. No presente estudo é proposto um método alternativo através de uma equação logística modificada, incluindo-se uma assíntota variável (A). Testou-se igualmente o uso do Índice Gonadossomático (GSI) como indicativo do status reprodutivo para fêmeas de peixes. O método é demonstrado com dados de quatro espécies de peixes Neotropicais: Characiformes: Astyanax fasciatus (n = 473) e Oligosarcus robustus (n = 297); Siluriformes: Loricariichthys anus (n = 427) e Trachelyopterus lucenai (n = 195). Os resultados obtidos foram suficientemente estáveis para propor-se o emprego do método para outras espécies de peixes com diferentes histórias de vida, mesmo que em programas de amostragem limitados. Sugere-se, entretanto, avaliação da metodologia em larga escala como forma de identificar-se possíveis desvios da abordagem proposta.


Subject(s)
Animals , Female , Statistics as Topic , Gonads/growth & development , Sexual Maturation/physiology , Catfishes/growth & development , Catfishes/embryology , Fishes/growth & development , Fishes/embryology
8.
Neotrop. ichthyol ; 7(4): 647-658, 2009. mapas, tab, graf
Article in English | LILACS, VETINDEX | ID: lil-536341

ABSTRACT

The aim of the present study was to identify the distribution patterns of migratory fishes in the Jacuí river basin (Rio Grande do Sul, South Brazil), proposing a statistical model of presumed distribution based on geomorphologic environmental data. Through maps of occurrence probability, we hope to contribute to decisions regarding basin environmental management. The analyzed species were: Salminus brasiliensis (dourado), Leporinus obtusidens (piava), Prochilodus lineatus (grumatã) and Pimelodus pintado (pintado). Samples were made through interviews with fishermen and local inhabitants, covering the main channel and tributaries of the rivers Jacuí, Taquari-Antas, Vacacaí, Vacacaí-Mirim, Pardo, Pardinho, Sinos, and Caí. The sampling program resulted in 204 interviews, being 187 considered as valid in 155 different sampling points. The probability of migratory fish occurrence was adjusted through the LOGIT routine of the Idrisi Andes Software: P = e(b0 + b1 . altitude + b2 . basin area) . (1 + e(b0 + b1 . altitude + b2 . basin area))-1, where P is the occurrence probability of the species (0-1) and b0, b1 and b2 are the equation parameters. Model accuracy, for estimating presence, ranged from 82 percent to 93 percent. Pimelodus pintado was cited to occur in 121 points among the 155 sampled (78.06 percent), Prochilodus lineatus in 72 (46.45 percent), L. obtusidens in 62 (40.00 percent) and S. brasiliensis in 58 (37.42 percent). Equation parameters were estimated (± standard error) as follow: S. brasiliensis: b0 = -2.8762 ± 0.2597; b1 = 1.3028 ± 0.0332; b2 = 1.1487 ± 0.0301; L. obtusidens: b0 = -0.8364 ± 0.2213; b1 = -1.5564 ± 0.0462; b2 = 0.9947 ± 0.0206; Prochilodus lineatus: b0= 0; b1= -1.3067 ± 0.0544; b2= 0.8128 ± 0.0177; Pimelodus pintado: b0= -0.9487 ± 0.3688; b1= -0.8269 ± 0.0496; b2= 0.9255 ± 0.0304.(AU)


O objetivo do presente estudo foi identificar o padrão de distribuição de peixes migradores da bacia hidrográfica do rio Jacuí (Rio Grande do Sul, Sul do Brasil), propondo um modelo matemático de distribuição presumida baseado em parâmetros ambientais geomorfológicos. Através de mapas de probabilidade de ocorrência, espera-se contribuir para a tomada de decisões relacionadas ao gerenciamento desta bacia hidrográfica. As espécies analisadas foram: Salminus brasiliensis (dourado), Leporinus obtusidens (piava), Prochilodus lineatus (grumatã) e Pimelodus pintado (pintado). As amostras foram obtidas a partir de entrevistas com pescadores e moradores locais, percorrendo-se a calha principal dos rios Jacuí, Taquari-Antas, Vacacaí, Vacacaí-Mirim, Pardo, Pardinho, Sinos e Caí. O programa de amostragens resultou em 204 entrevistas, sendo 187 consideradas como válidas em 155 pontos diferenciados. A probabilidade de ocorrência de peixes migradores foi ajustada utilizando-se a rotina LOGIT do software Idrisi Andes: P = e(b0 + b1 . altitude + b2 . área de bacia) . (1 + e(b0 + b1 . altitude + b2 . área de bacia))-1; onde P é a probabilidade de ocorrência da espécie (0-1) e b0, b1 e b2 são os parâmetros da equação. Pimelodus pintado foi citado como presente em 121 pontos dentre os 155 amostrados (78.06 por cento), Prochilodus lineatus em 72 (46.45 por cento), L. obtusidens em 62 (40.00 por cento), e S. brasiliensis em 58 pontos (37.42 por cento). A precisão do modelo, para a presença estimada, ficou entre 82 por cento e 93 por cento. Os parâmetros estimados da equação são descritos a seguir: S. brasiliensis: b0= -2.8762 ± 0.2597; b1= -1.3028 ± 0.0332; b2= 1.1487 ± 0.0301; L. obtusidens: b0 = -0.8364 ± 0.2213; b1 = -1.5564 ± 0.0462; b2 = 0.9947 ± 0.0206; Prochilodus lineatus: b0 = 0; b1 = -1.3067 ± 0.0544; b2 = 0.8128 ± 0.0177; Pimelodus pintado: b0 = -0.9487 ± 0.3688; b1 = -0.8269 ± ...(AU)


Subject(s)
Animals , Statistical Distributions , Animal Migration , Fishes/growth & development , Linear Models
9.
Neotrop. ichthyol ; 5(4): 485-490, Oct.-Dec. 2007. graf, tab
Article in English | LILACS | ID: lil-471980

ABSTRACT

The growth of Atherinella brasiliensis (Quoy & Gaimard, 1824) was studied through monthly samples taken at Tramandaí Lagoon, Imbé County, Rio Grande do Sul, Brazil. Animals were captured using a beach seine net. Length-weight relationships and age- growth curves for males and females were adjusted. The growth parameters of the von Bertalanffy growth formulae are Linf=16.0 and k=0.883 for males and Linf=17.0 and k=0.825 for females. First reproduction occurred one year after recruitment. Once reaching maturity, adults of A. brasiliensis reproduced once more in the next spring with two-year-olds and disappeared soon after from size frequency distributions. A few captured animals showed a size compatible with an age of three years


O crescimento de Atherinella brasiliensis (Quoy & Gaimard, 1824) foi estudado através de amostras mensais na laguna de Tramandaí, Imbé, Rio Grande do Sul, Brasil. Os animais foram capturados com uma rede de arrasto de praia (picaré) de 15 m de comprimento, 3 m de altura e malha de 5 mm entre nós adjacentes. Relações peso/comprimento e curvas de crescimento em comprimento são ajustadas para machos e fêmeas. Os parâmetros da curva de crescimento de von Bertalanffy são Linf=16,0 e k=0,883 para machos e Linf=17,0 e k=0,825 para fêmeas. A primeira maturação ocorre um ano após o recrutamento. Uma vez atingida a maturidade, adultos de A. brasiliensis reproduzem mais uma vez na próxima primavera (com dois anos de idade) e desaparecem logo após nas distribuições de freqüências de comprimento. Poucos animais capturados apresentam tamanhos compatíveis com idade de três anos


Subject(s)
Animals , Life Cycle Stages , Longevity/physiology , Fishes/growth & development
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