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Estrutura populacional do Chicharro, Trachurus picturatus do Atlântico Nordeste
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Advisor(s)
Abstract(s)
Esta dissertação abordou duas temáticas principais: a identificação da estrutura do stock de chicharro, Trachurus picturatus (Bowdich, 1825), no sul do Atlântico nordeste e o estudo dos parâmetros de história de vida para a população da Madeira. A estrutura do stock de chicharro ainda é desconhecida e para identificar as unidades populacionais, foram selecionadas três áreas, Madeira, Portugal continental e Canárias, e utilizadas várias metodologias: morfologia do contorno do otólito, morfologia do corpo e análise parasitológica. Na primeira, foram analisados 100 otólitos por área, tendo os resultados da análise aos descritores elípticos de Fourier normalizados (NEFDs) revelado diferenças significativas entre as três áreas (classificação geral de 86.3%). Relativamente à morfologia do peixe, a atribuição de espécimes às localizações geográficas em estudo foi classificada corretamente em 80.7% das amostras (K = 0.67). Estes resultados juntamente com o padrão de infeção dos parasitas Anisakis spp., Rhadinorhynchus sp. e Nybelinia sp. confirmaram a distinção de 3 unidades populacionais no sul do Atlântico nordeste. Nos parâmetros de história de vida, a idade foi determinada a partir de 1405 espécimes, colhidos entre 2009 e 2010. A verificação das leituras foi efetuada segundo a análise do incremento marginal e a evolução mensal do tipo de bordo. Os resultados mostraram a existência de dois anéis por ano, tendo sido atribuídos sete grupos de idade (0-6). Não se verificaram diferenças significativas entre sexos nos comprimentos médios à idade e nas curvas de crescimento de von Bertalanffy. Os parâmetros de crescimento estimados foram: L∞ = 27.98 cm, k = 0.266 ano-1 e t0 = -2.713 ano. A relação peso-comprimento estimada para todos os indivíduos foi de Wt = 0.00411Lt3.230. A época de desova estendeu-se de janeiro a abril. A espécie atinge a maturidade sexual no primeiro ano com comprimentos de 17.06 e 17.04 cm para fêmeas e machos respetivamente.
This thesis addressed two main themes: the identification of the stock structure of blue jack mackerel, Trachurus picturatus (Bowdich, 1825), in the South Atlantic Northeast and the study of life history parameters for the Madeira population. The stock structure of blue jack mackerel is still unknown, and to identify the populational units, three areas were selected, Madeira, mainland Portugal and the Canary Islands, and used different methodologies: otolith morphometry, body shape morphometry and parasitological analysis. For the first methodology, 100 otoliths were analysed by area, and the results of the analysis made to elliptical Fourier descriptors (NEFDs) shown significant differences among the three areas (overall rating of 86.3%). Regarding the body shape morphometry, assigning specimens to the geographic locations under study were correctly classified in 80.7% of the samples (K = 0.67). These results along with the pattern of infection of the parasites Anisakis spp., Rhadinorhynchus sp. and Nybelinia sp. pointed to the existence of 3 stocks in the South Atlantic Northeast. In life history parameters, age was determined on 1405 specimens collected between 2009 and 2010. Otolith reading verification was performed according to marginal increment analysis and monthly analysis of otoliths edge type. The results confirmed the presence of two rings per year, being allocated seven age groups (0-6). There was no significant differences between sexes in mean lengths-at-age and in the von Bertalanffy growth curves. The growth parameters estimated were: L∞ = 27.98 cm, k = 0.266 year-1 and t0 = -2.713 year. The length-weight relationships for sexes combined was Wt = 0.00411Lt3.230. The spawning season extended from January to April. The species reaches sexual maturity in the first year (0.69 year, females and males) with total length of 17.06 cm for females and 17.04 cm for males.
This thesis addressed two main themes: the identification of the stock structure of blue jack mackerel, Trachurus picturatus (Bowdich, 1825), in the South Atlantic Northeast and the study of life history parameters for the Madeira population. The stock structure of blue jack mackerel is still unknown, and to identify the populational units, three areas were selected, Madeira, mainland Portugal and the Canary Islands, and used different methodologies: otolith morphometry, body shape morphometry and parasitological analysis. For the first methodology, 100 otoliths were analysed by area, and the results of the analysis made to elliptical Fourier descriptors (NEFDs) shown significant differences among the three areas (overall rating of 86.3%). Regarding the body shape morphometry, assigning specimens to the geographic locations under study were correctly classified in 80.7% of the samples (K = 0.67). These results along with the pattern of infection of the parasites Anisakis spp., Rhadinorhynchus sp. and Nybelinia sp. pointed to the existence of 3 stocks in the South Atlantic Northeast. In life history parameters, age was determined on 1405 specimens collected between 2009 and 2010. Otolith reading verification was performed according to marginal increment analysis and monthly analysis of otoliths edge type. The results confirmed the presence of two rings per year, being allocated seven age groups (0-6). There was no significant differences between sexes in mean lengths-at-age and in the von Bertalanffy growth curves. The growth parameters estimated were: L∞ = 27.98 cm, k = 0.266 year-1 and t0 = -2.713 year. The length-weight relationships for sexes combined was Wt = 0.00411Lt3.230. The spawning season extended from January to April. The species reaches sexual maturity in the first year (0.69 year, females and males) with total length of 17.06 cm for females and 17.04 cm for males.
Description
Keywords
Trachurus picturatus Atlântico Nordeste Identificação de stocks Morfologia da forma do corpo e do otólito Parasitas Idade Crescimento e fecundidade Trachurus picturatus Atlantic Northeast Stock identification Body shape and otolith morphometry Parasites Age Growth and fecundity Ciências Biológicas . Faculdade de Ciências da Vida