The growth of individuals is analyzed in the mass tropical species manybar goatfish Parupeneus multifasciatus from the Nha Trang Bay of the South China Sea. The relationship between the body weight ...and body length is determined for the females and males. Among the fishes larger 180 mm fork length (FL), the males prevail. Linear growth of the sagitta is characterized by negative allometry in relation to body length, and sagitta growth in length is faster than in width. Age of fish assessed based on the analysis of daily increments on the sagitta does not exceed three years, and the majority of individuals reach the first sexual maturity by the age of one year. The growth rate of the fish is characterized by a large individual variation.
The estimation of weight–length relationship of fish species requires having data on individual weight and length. However, individual weight data are often not available because they are too ...expensive or not feasible to gather and the relationship cannot be explicitly estimated. Yet, in this paper I develop a simple methodology that allows me to estimate a weight–length relationship when only aggregate weight data are available. To show its usefulness, the methodology is applied to the American lobster (
Homarus americanus
) population of Long Island Sound. Results indicate the existence of isometric growth for American lobsters in this geographical location:
W
= 0.000924
L
2.9619
. The estimated relationship is used to predict individual weight of lobsters which are then used to construct biomass indexes for three size classes of lobsters for the time period 1987–2006. This analysis suggests that is not necessary to invest efforts in collecting individual weight data to be able to construct meaningful indicators of fish population.
La relación longitud-peso y el factor de condición (K) son descriptores de gran interés en la biología de poblaciones de peces, ya que aportan información fundamental sobre estrategias de ...crecimiento, estado nutricional y reproducción. También son parámetros ampliamente utilizados para comparar la condición de poblaciones que habitan en sistemas acuáticos con distintos grados de intervención antrópica. Por ello, conocer el comportamiento de poblaciones que habitan en ecosistemas prístinos, entrega información de base, relevante para comprender cambios o efectos en poblaciones sometidas a estas presiones. El río San Pedro de la cuenca del Valdivia, sur de Chile, es un sistema que se caracteriza por su actual bajo nivel de intervención, su alta diversidad íctica y baja abundancia de especies introducidas. En este trabajo describimos la relación longitud-peso y factor de condición de 12 especies de peces nativos del río San Pedro, durante más dos ciclos anuales, analizando sus estrategias de crecimiento y variabilidad estacional del factor de condición. Los resultados de la relación longitud-peso muestran que gran parte de las especies presentan un crecimiento isométrico, especialmente Diplomystes camposensis, Basilichthys australis y Brachygalaxias bullocki. Sin embargo, algunas especies presentan una tendencia a la alometría (Galaxias maculatus, Galaxias platei y Trichomycterus areolatus). Los valores de K muestran que especies como Percilia gillissi poseen una marcada variabilidad anual, posiblemente asociada a las épocas reproductivas y de mayor oferta de alimento. Entregamos esta información como base para entender el funcionamiento de poblaciones ícticas en condiciones naturales y para ser utilizada en la evaluación de futuros proyectos que puedan impactar estos ecosistemas.The length-weight relationship and condition factor (K) are useful descriptors in population fish biology, because they provide essential information on growth strategies, nutritional status and reproduction. They are also parameters widely used to compare the condition of aquatic systems with varying degrees of human intervention. Therefore, understanding the dynamics of populations in pristine ecosystems, provides relevant basic information to understanding changes or effects in populations under these pressures. The San Pedro river (Valdivia basin), southern Chile, is a system characterized by its current low intervention level, high fish diversity and low abundance of introduced species. We describe the length-weight relationship and condition factor of 12 native fish of the San Pedro river, for over two annual cycles, analyzing their growth strategies and seasonal variability in condition factor. The results of the length-weight show that the most of species exhibit isometric growth, especially Diplomystes camposensis, Basilichthys australis and Brachygalaxias bullocki, however, some species have a tendency to allometry (Galaxias maculatus, Galaxias platei and Trichomycterus areolatus). The values of K show that species such as Percilia gillissi have a strong annual variability, associated with the breeding season and greater supply of food. We give this information as baseline data to understand the functioning of fish populations in natural conditions and to be used for the evaluation of future projects that may impact these ecosystems.
The present study has assessed spatial and temporal variations in the length structure of Hemigrammus marginatus Ellis, 1911 and estimated growth parameters for the species. Sampling was carried out ...in five streams in the Vitória and Piravevê sub-basins of the Ivinhema River from January to December 2002. A total of 933 specimens of H. marginatus were caught (97 in the Vitória sub-basin and 836 in the Piravevê sub-basin). Mean length of the individuals caught in the Piravevê sub-basin was shorter (21.58 mm, SD = 4.67) than that of individuals caught in the Vitória sub-basin (29.24 mm, SD = 4.42). Analysis of condition factor calculated from the weight/length relationship revealed that the values were constant both spatially (between sub-basins) and temporally (throughout the year). In the Piravevê sub-basin, the theoretical maximal length estimated for this species was 37.26 mm, with natural mortality rate of 1.22 year¹, growth rate (k) of 0.66 year-1, and growth performance index (w) of 3.80 and 4.25 years of longevity. The input of new individuals in the population occurs twice per year, with greater recruitment at the peak of the rainy season (May) and the peak of the dry season (August). PUBLICATION ABSTRACT
Ecosystems may reflect environmental changes in many respects, from the debilitation of individuals to alterations in community composition. Equally, population parameters may provide reliable ...indications of environmental changes. Members of the sciaenid fish genus Stellifer are usually very abundant where they occur, often with two or more species living in sympatry. Here, the population dynamics of three Stellifer species from southeastern Brazil were assessed. Sampling was carried out in shallow marine areas of Caraguatatuba Bay, from August 2003 to October 2004. The species evaluated were Stellifer rastrifer (n=3183), S. brasiliensis (n=357) and S. stellifer (n=116). The area under greater continental influence tended to support more, but smaller individuals. Size variations over time were similar among species and negatively correlated with Krel, which showed smooth fluctuations. The general length-frequency distribution was concentrated between 6.0 and 9.0 cm, and the great majority of females did not present mature gonads during the sampling period. The findings support the existence of a stratification by size for these species, indicating that the area is essential for the development of younger fish. Failure to consider these characteristics for the management of similar areas may have serious implications for these environments.
Os ecossistemas podem refletir mudanças ambientais em muitos aspectos, desde o enfraquecimento dos indivíduos até alterações na composição da comunidade. Do mesmo modo, os parâmetros populacionais podem fornecer indicações confiáveis de mudanças ambientais. Sciaenídeos do gênero Stellifer são peixes geralmente muito abundantes e em suas populações é frequente a ocorrência de duas ou mais espécies simpátricas. No presente trabalho, a dinâmica populacional de três espécies de Stellifer do sudeste do Brasil foi avaliada. A amostragem ocorreu em águas rasas das zonas marinhas da Baía de Caraguatatuba, de agosto de 2003 a outubro de 2004. As espécies avaliadas foram Stellifer rastrifer (n = 3.183), S. brasiliensis (n = 357) e S. stellifer (n = 116). Os resultados mostraram que a área sob maior influência continental tende a suportar um número maior de indivíduos menores. Variações de tamanho ao longo do tempo foram semelhantes entre as espécies e negativamente correlacionadas com o Krel, que apresentou flutuações suaves. De modo geral a distribuição de freqüência de comprimento ficou concentrada entre 6,0 e 9,0 cm e para a grande maioria das fêmeas as gônadas se apresentaram imaturas durante o período avaliado. Os resultados suportam a existência de estratificação populacional por tamanho dentro destas espécies, indicando que a área é apropriada para o desenvolvimento de juvenis. A desconsideração de tais características pode acarretar sérias implicações para a gestão dessas áreas.
Biologia reprodutiva de Hexanematichthys proops (Siluriformes, Ariidae) no litoral ocidental maranhense Cantanhêde, Geuza(Universidade Estadual de Maringá Departamento de Biologia); Castro, Antonio C. L. de(Universidade Federal do Maranhão Departamento de Oceanografia e Limnologia); Gubiani, Éder A.(Universidade Estadual de Maringá Departamento de Biologia)
Iheringia. Série Zoologia,
2007, Letnik:
97, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Objetivou-se investigar a influência dos índices gonadais e nutricionais sobre a biologia reprodutiva de Hexanematichthys proops (Valenciennes, 1840) (Siluriformes, Ariidae) na costa ocidental do ...Maranhão entre julho de 2001 e julho de 2002. Houve uma significante dominância de fêmeas quando considerado o período total amostrado. A relação peso/comprimento apresentou uma significante diferença entre os sexos em relação ao coeficiente de alometria, embora ambos tenham apresentado crescimento alométrico positivo. Análises da curva de maturação baseadas na variação mensal dos índices gonadossomático e hepatossomático sugerem que o período reprodutivo ocorre entre outubro e maio. A variação mensal do fator de condição revelou que as fêmeas apresentaram condições gerais inferiores aos machos durante todo o período amostral. Foi observado que a diminuição do peso do fígado ocorre durante a maturação gonadal e processos reprodutivos. Análises do índice de repleção médio mostraram que os peixes exibem melhores condições alimentares antes e depois do período reprodutivo.
The aim of this study was to investigate the influence of gonadal and nutritional indexes on the reproductive biology of Hexanematichthys proops (Valenciennes, 1840) (Siluriformes, Ariidae) in the western coast of Maranhão, between July 2001 and July 2002. A significant female dominance was observed during the study period. The weight/length relationship showed a significant difference between sexes in relation to the alometric coefficient, although both sexes showed positive alometric growth. Analysis of the maturation curve based on the monthly variation of the gonadosomatic and hepatosomatic index suggests that the reproductive period occurs between October and May. The month variation of the condition factor reveals that females presented general conditions poorer than males during all the study period. It was observed that the loss of liver weight occurs during gonadal maturation and reproductive processes. Analysis of the mean repletion index showed that the fishes exhibited better feeding conditions before and after the reproductive season.
In this paper are presented the results of the growth parameters for the carp population. The study was realized in the 2006-2009 period on a total number of 367 carp specimens caught into the Danube ...river km 170-196 (the arms: Cravia, Calia, and Fundu Mare Island). In order to estimate the population growth characteristic of the carp population the following relationship was determined: length - weight (L-W) using equation W = a· Lb. The value of the coefficient b indicates an allometric increase, meaning the length increases faster than weight. Moreover, the good value of this coefficient, considered also as a condition factor (b = 2.845), shows us good growth conditions for this species in the researched area. Estimation of the growth parameters (von Bertalanffy) L∞ , k, to, led to obtaining of comparable values with other nearby regions carp populations.
Objetivou-se investigar a influência dos índices gonadais e nutricionais sobre a biologia reprodutiva de Hexanematichthys proops (Valenciennes, 1840) (Siluriformes, Ariidae) na costa ocidental do ...Maranhão entre julho de 2001 e julho de 2002. Houve uma significante dominância de fêmeas quando considerado o período total amostrado. A relação peso/comprimento apresentou uma significante diferença entre os sexos em relação ao coeficiente de alometria, embora ambos tenham apresentado crescimento alométrico positivo. Análises da curva de maturação baseadas na variação mensal dos índices gonadossomático e hepatossomático sugerem que o período reprodutivo ocorre entre outubro e maio. A variação mensal do fator de condição revelou que as fêmeas apresentaram condições gerais inferiores aos machos durante todo o período amostral. Foi observado que a diminuição do peso do fígado ocorre durante a maturação gonadal e processos reprodutivos. Análises do índice de repleção médio mostraram que os peixes exibem melhores condições alimentares antes e depois do período reprodutivo.The aim of this study was to investigate the influence of gonadal and nutritional indexes on the reproductive biology of Hexanematichthys proops (Valenciennes, 1840) (Siluriformes, Ariidae) in the western coast of Maranhão, between July 2001 and July 2002. A significant female dominance was observed during the study period. The weight/length relationship showed a significant difference between sexes in relation to the alometric coefficient, although both sexes showed positive alometric growth. Analysis of the maturation curve based on the monthly variation of the gonadosomatic and hepatosomatic index suggests that the reproductive period occurs between October and May. The month variation of the condition factor reveals that females presented general conditions poorer than males during all the study period. It was observed that the loss of liver weight occurs during gonadal maturation and reproductive processes. Analysis of the mean repletion index showed that the fishes exhibited better feeding conditions before and after the reproductive season.
Weight-length relationships (WLR) of 57 fish species belonging to 22 families from the coastal rivers of the south-eastern of Ivory Coast were studied. Samples were collected with two fleets of ...monofilament gill nets. The value of the exponent b in the WLR (W=aLb) ranged from 2.213 to 3.729. The mean and the median values were 2.892 and 2.899 respectively, whereas 50% of the value ranged between 2.787 and 3.048. For 11 species, these relationships are described for the first time for this sub-region.Original Abstract: U radu je istrazivan tezinsko-duzinski odnos (WRL) 57 vrsta riba koje su pripadale 22-dvjema porodicama, a koje se nalaze u rijekama jugoistocnog dijela Obale Bjelokosti. Uzorci su sakupljeni dvjema vrstama mreza. Vrijednost eksponenta b u WRL (W=aLb) kretao se izmedju 2,213 i 3,729. Prosjecna i srednja vrijednost bile su 2,892, odnosno 2,899, dok je 50% te vrijednosti bilo izmedju 2,787 i 3,048. Za 11 vrsta ti su odnosi opisani prvi put u ovoj podregiji.
Weight-length and condition factor relationship of Sperata sarwari (Singhari), from Mangla Lake, Pakistan Shakir, H.A. (Punjab Univ., Quaid-e-Azam Campus, Lahore (Pakistan). Dept. of Zoology); Mirza, M.R. (Government Coll. Univ., Lahore (Pakistan). Dept. of Zoology); Khan, A.M. (Punjab Univ., Quaid-e-Azam Campus, Lahore (Pakistan). Dept. of Zoology) ...
Journal of animal and plant sciences,
(2008), Letnik:
18, Številka:
4
Journal Article
Recenzirano
Fifty fresh water specimens of Singhari, (Sprerata sarwari) ranging in total length from 24.9 - 93.7 cm and body weight from 66 - 4824 g were sampled, to study the parameters of weight-length and ...condition factor relationship from Mangla Lake Pakistan. Log transformed regression were used to test the growth. The value of growth coefficient (b = 3.57) indicates allometric growth in the studied specimens. Condition factor increases with increasing length or weight. The predictive equation can be used to estimate parameters investigated with a fair amount of accuracy within the size range studies.
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