Associações de espécies de peixes em ambientes lóticos da bacia do rio Iguatemi, Estado do Mato Grosso do Sul - DOI: 10.4025/actascibiolsci.v25i2.2024

The aim of this paper is to describe the patterns of associations between fish species and their distribution in lotic habitats at basin level. Samples were accomplished in 27 localities of Iguatemi river basin, distributed in four environments (Iguatemi river, Jogui river, Puitã river and streams). The presence/absence data of those species which occurred in 2 or more sites were submitted at multivariate methods with the aim to describe the major species associations. The species distribution was considered determinative in these communities (C-score = 17,33; P = 0,000), with significant difference among the studied environments (ANOSIM r = 0,082; P = 0,012), with verified difference between Iguatemi river and streams (P = 0,001) and also streams and Jogui river (P = 0,014). We verified a strong segregation among species from headstreams and more discharge river stretches or even larger streamsCom o objetivo de descrever os padrões das associações entre espécies de peixes e sua distribuição nos ambientes lóticos ao nível da bacia, foram realizadas amostragens em 27 locais na bacia do rio Iguatemi-MS, distribuídas em quatro ambientes (rio Iguatemi, rio Jogui, rio Puitã e riachos). Os dados de presença/ausência das espécies que ocorreram em dois ou mais locais foram submetidos a métodos multivariados com o objetivo de descrever os principais padrões de associação entre espécies. A distribuição das espécies foi considerada determinística nessas comunidades (C-score = 17,33; P = 0,000), existindo diferença significativa entre os ambientes estudados (ANOSIM r = 0,082; P = 0,012), sendo constatada diferença entre rio Iguatemi e riachos (P = 0,001) e riachos e rio Jogui (P = 0,014). Constatamos uma clara segregação entre as espécies de riachos de cabeceiras e de trechos mais caudalosos dos rios ou mesmo de riachos com maior vazã

Organização das assembléias de peixes em riachos da bacia do rio Iguatemi, Estado do Mato Grosso do Sul - DOI: 10.4025/actascibiolsci.v27i2.1350

Aiming to describe the patterns of the fish assemblages organization in streams of the Iguatemi River basin we sampled streams with seine nets and sieves from November/1999 to August/2000. We collected 567 individuals distributed in 24 species. We detected statistically significant influence of the streams characteristics upon species diversity. The species composition was hardly explained by the physical and chemical characteristics of the streams. Then we detected significant influence of the fish ecomorphology in the species occurrence (Mantel r = -0,34; P = 0,04), but not in the distribution of its abundance (Mantel r = -0,21; P = 0,07). We verified through the species co-occurrence index (C-score) that its composition in the studied streams is stochasticComo o objetivo de descrever os padrões de organização das comunidades de peixes em riachos da bacia do rio Iguatemi amostramos riachos com redes de espera e de arrasto no período de novembro/1999 a agosto/2000. Coletamos 567 indivíduos distribuídos em 24 espécies. Constatamos influência significativa das características dos riachos sobre a diversidade de espécies. A composição de espécies foi pouco explicada pelas características dos riachos. Verificamos influência significativa da morfologia na distribuição em ocorrência das espécies (Mantel r = -0,34; P = 0,04), mas não na distribuição em sua abundância (Mantel r = -0,21; P = 0,07). Comprovamos através do índice de co-ocorrência (C-score) das espécies que sua composição nos riachos estudados é estocástic

Idade e crescimento do tubarão-martelo-entalhado, Sphyrna lewini (Griffith and Smith, 1834), da costa sul do Brasil

Submitted by Paula Gautério ([email protected]) on 2014-01-21T19:17:02Z No. of bitstreams: 1 Age and growth of the scalloped hammerhead shark, Sphyrna lewini (Griffith and Smith, 1834), from the southern Brazilian coast.pdf: 380625 bytes, checksum: e651064e344c45b51239b178e8978ac6 (MD5)Approved for entry into archive by cristiane soares ([email protected]) on 2014-01-23T16:49:57Z (GMT) No. of bitstreams: 1 Age and growth of the scalloped hammerhead shark, Sphyrna lewini (Griffith and Smith, 1834), from the southern Brazilian coast.pdf: 380625 bytes, checksum: e651064e344c45b51239b178e8978ac6 (MD5)Made available in DSpace on 2014-01-23T16:49:57Z (GMT). No. of bitstreams: 1 Age and growth of the scalloped hammerhead shark, Sphyrna lewini (Griffith and Smith, 1834), from the southern Brazilian coast.pdf: 380625 bytes, checksum: e651064e344c45b51239b178e8978ac6 (MD5) Previous issue date: 2011Age and growth studies for the scalloped hammerhead shark, Sphyrna lewini (Griffith and Smith, 1834) caught along the southern Brazilian coast, were based on ring measurements of vertebrae sections of 115 males, 116 females and 14 unknown sexed sharks between 48 and 344 cm total length (TL). The von Bertalanffy growth models were best fit using back-calculated data. The growth parameters obtained for males, were L∞ = 266 cm; K = 0.05/year; L0 = 47 cm. For females, L∞ = 300 cm; K = 0.05/year; L0 = 51 cm. An adult female reached 217 cm TL and was 31.5 years old. On the other hand, an adult male was 29.5 years old and measured 234 cm TL. Longevity estimate for males and females was 55 years. Therefore, S. lewini is a long-lived fish. Ageing precision, based on the IAPE index, was 5.6%. Marginal Increment analysis based on MIR index from hammerheads smaller than 105 cm, compared with the percentual of opaque and hyaline bands found per month ageing whole vertebrae, showed an annual ring formation, i.e., in winter.O estudo da idade e do crescimento do tubarão-martelo-entalhado, Sphyrna lewini (Griffith and Smith, 1834), na costa sul do Brasil, baseou-se na leitura de anéis em seções de vértebras de 115 machos, 116 fêmeas e de 14 exemplares com sexo indeterminado, com comprimentos totais (CT) entre 48 e 344 cm. Modelos de crescimento de von Bertalanffy foram mais bem ajustados aos dados de idade e comprimento retrocalculados, considerando sexos em separado. Os parâmetros de crescimento obtidos para os machos foram L∞ = 266 cm; K = 0,05/ano; L0 = 47 cm. Para as fêmeas L∞ = 300 cm; K = 0,05/ano; L0 = 51 cm. Uma fêmea adulta atingiu um CT de 217 cm e uma idade de 31,5 anos. Por sua vez, um macho adulto tinha 29,5 anos e CT de 234 cm. A estimativa de longevidade para machos e fêmeas foi de 55 anos. O índice de erro percentual médio (IAPE), que avalia a precisão na leitura de idades, foi de 5,6%. A análise do incremento marginal baseada no índice MIR e aplicada em tubarões com CT < 105 cm, comparada com o percentual de bandas opacas e hialinas mensais, obtido através de leituras de vértebras inteiras, indicou um padrão anual na formação dos anéis, ou seja, anéis de inverno

Age and growth of the scalloped hammerhead shark, Sphyrna lewini (Griffith and Smith, 1834), from the southern Brazilian coast

Age and growth studies for the scalloped hammerhead shark, Sphyrna lewini (Griffith and Smith, 1834) caught along the southern Brazilian coast, were based on ring measurements of vertebrae sections of 115 males, 116 females and 14 unknown sexed sharks between 48 and 344 cm total length (TL). The von Bertalanffy growth models were best fit using back-calculated data. The growth parameters obtained for males, were L∞ = 266 cm; K = 0.05/year; L0 = 47 cm. For females, L∞ = 300 cm; K = 0.05/year; L0 = 51 cm. An adult female reached 217 cm TL and was 31.5 years old. On the other hand, an adult male was 29.5 years old and measured 234 cm TL. Longevity estimate for males and females was 55 years. Therefore, S. lewini is a long-lived fish. Ageing precision, based on the IAPE index, was 5.6%. Marginal Increment analysis based on MIR index from hammerheads smaller than 105 cm, compared with the percentual of opaque and hyaline bands found per month ageing whole vertebrae, showed an annual ring formation, i.e., in winter.O estudo da idade e do crescimento do tubarão-martelo-entalhado, Sphyrna lewini (Griffith and Smith, 1834), na costa sul do Brasil, baseou-se na leitura de anéis em seções de vértebras de 115 machos, 116 fêmeas e de 14 exemplares com sexo indeterminado, com comprimentos totais (CT) entre 48 e 344 cm. Modelos de crescimento de von Bertalanffy foram mais bem ajustados aos dados de idade e comprimento retrocalculados, considerando sexos em separado. Os parâmetros de crescimento obtidos para os machos foram L∞ = 266 cm; K = 0,05/ano; L0 = 47 cm. Para as fêmeas L∞ = 300 cm; K = 0,05/ano; L0 = 51 cm. Uma fêmea adulta atingiu um CT de 217 cm e uma idade de 31,5 anos. Por sua vez, um macho adulto tinha 29,5 anos e CT de 234 cm. A estimativa de longevidade para machos e fêmeas foi de 55 anos. O índice de erro percentual médio (IAPE), que avalia a precisão na leitura de idades, foi de 5,6%. A análise do incremento marginal baseada no índice MIR e aplicada em tubarões com CT < 105 cm, comparada com o percentual de bandas opacas e hialinas mensais, obtido através de leituras de vértebras inteiras, indicou um padrão anual na formação dos anéis, ou seja, anéis de inverno

Computer intensive methods for controlling bias in a generalized species diversity index

The use of diversity indices is a common practice in studies of community ecology. Historically, the main indices were derived by Shannon and Simpson. Currently, these two indices are recognized as part of families of entropy-based indices, which generally include species richness as another particular case. This paper evaluates the statistical properties of one of these families, the Tsallis index, as dependent on four factors: (i) spatial distribution of individuals; (ii) species-abundance distributions; (iii) sampling method and (iv) the estimator. To do so, we carried out computer simulations. The maximum likelihood estimator under all scenarios produced more biased estimates than the two computationally intensive estimation methods (i.e., Jackknife and bootstrap). The Broken-Stick was the species-abundance distribution that led to lowest bias, particularly in the species richness estimation. Intermediate levels of spatial-aggregation of individuals were also related to less biased estimations of diversity. The effect of quadrat size upon the bias of estimation was weak, despite the fact that such sampling method often produces a non-random sample of individuals. On the one hand, the Jackknife method was more accurate than the bootstrap, although both methods have shown poor performances for diversity indices that emphasize species richness. On the other hand, if confidence intervals are needed for individual community samples, the bootstrap is strongly recommended over the Jackknife. (C) 2013 Elsevier Ltd. All rights reserved.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

A pesca de emalhe-de-superficie de santa catarina direcionada à captura dos tubarões-martelo, Sphyrna lewini (Griffith & Smith 1834) E Sphyrna zygaena (Linnaeus 1758).

Durante o período de maio de 2005 a outubro de 2006 a frota de emalhe em Santa Catarina esteve composta por 245 barcos. Destes, 194 desembarcaram em Itajaí, Navegantes e Porto Belo, 21 em Laguna e 30 em Passo de Torres. O emalhe-desuperfície, é mais intenso nos meses de primavera a outono. A altura média das redes foi de 18 m (n = 16; s = 7 m), com comprimento de 5222 m (n = 16; s = 1929 m) e tamanho de malha em 32,8 cm (n = 17; s = 9,3 cm). O comprimento total médio dos tubarões-martelo-entalhados (Sphyrna lewini) foi de 171,8 cm (n = 717; s = 43,3 cm) e mediana igual a 170 cm e com grande quantidade de juvenis de grande porte nos desembarques. Os machos foram mais numerosos nas capturas (72 %). As médias anuais das capturas ajustadas pelo modelo ANCOVA, mostraram declínio de 2000 a 2005. Em termos sazonais, houve um padrão de crescimento no sentido inverno-primavera-verão-outono. Foram estabelecidos Pontos de Referência Objetivos (PRO´s) e Pontos de Referência Limites (PRL´s) como medidas de conservação e manejo sustentável para S.lewini, ou seja: PRO´s: Redução anual de 30 % no comprimento e na altura da redes até serem atingidas as dimensões-limite de 2500 m e 10 m, respectivamente; defeso para S. lewini entre os meses de novembro e março, inclusive; áreas de exclusão à pesca nos berçários costeiros de S. lewini (< 20 m de profundidade). PRL´s: A utilização da malha de 40 cm (entre-nós opostos, esticada) na panagem da rede ; O comprimento total de 200 cm, como tamanho mínimo de captura permitido para S.lewini .From May, 2005 to October, 2006, the gillnet fleet in Santa Catarina was composed of 245 boats. From these, 194 landed in Itajaí, Navegantes and Porto Belo; 21 in Laguna; and 30 in Passo de Torres. Driftnet activity is higher between Spring and Autumn. The average net height was 18 m (n = 16; s = 7 m), net length 5222 m (n = 16; s = 1929 m) and mesh size 32,8 cm (n = 17; s = 9,3 cm). The average total length of the scalloped hammerheads landed was 171,8 cm (n = 717; s = 43,3 cm), median = 170 cm and there were high quantities of big juveniles landed. Sex-ratio was higher for males (72 %). ANCOVA models showed an average catch decline between 2000 and 2005. The catches increased from winter to autumn. Reference points were established for the sustainable management and conservation of S.lewini: (1) 30 % annual reduction on driftnet dimensions until reaching the size limits of 2500 m length and 10 m high; (2) Closure season from november to march; (3) Closure areas (< 20 m depth) to protect pupping grounds; (4) Mesh-size limit of 40 cm (between knots, stretched); (5) 200 cm as the minimum catch size for the scalloped hammerhead shark

Breeding, growth and exploitation of Brachyplatystoma rousseauxii Castelnau, 1855 in the Caqueta River, Colombia

The main life history traits of the large Amazonian migratory catfish Brachyplatystoma rousseauxii were determined in the Caqueta River, Colombia. The breeding season occurred during the rising and falling water periods. The size at first sexual maturity was significantly larger for females (88.5 cm Ls) than males (81.7 cm). Both males and females reproduce for the first time between their third and fourth year. The growth characteristics were estimated using length frequency analyses. Females grew systematically larger than males, the difference being about 9% after the first year and increasing to 12% for ten years old individuals. Mortality estimates, calculated from different models, some taking into account the effect of body size, ranged from 0.32 to 0.42 year-1 for natural mortality and from 0.72 to 0.82 year-1 for fishing mortality, indicating high fishing pressure in the Caqueta River, higher than in the Peruvian Amazon. Resulting exploitation rates (0.63 to 0.72) pointed towards overexploitation of the species in the Caqueta. The situation calls for a concerted management between the countries sharing this resource (Brazil, Colombia, and Peru) and potential solutions are proposed

Environmental factors associated with southern brown shrimp (Penaeus subtilis) yield at Brazilian Amazon coast

We evaluated the relationship between southern brown shrimp&nbsp;Penaeus subtilis&nbsp;(Pérez Farfante, 1967) yield and environmental parameters on the Amazon continental shelf. We analysed monthly fishing effort data (number of days spent at sea) and yield (kg of tails) collected between 1978 and 2009. A causal relationship had been expected between Amazon River discharge during the main period of shrimp occurrence in estuarine waters (considering post larval settlement and juvenile recruitment in second semester of each year) and adult abundance (represented by fishery yield in the first semester of the following year). We detected significant correlations between monthly river discharge and yield with a negative lag of four months, and between river discharge during the dry season (June to November) and yield in the following year. In general, low and high discharges during a given year were associated with high and low fishery yields, respectively, during the following year