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Percorrer por autor "Maia, Francisco"

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  • ABUNDANCE, DISTRIBUTION AND POPULATION STRUCTURE OF THE COMMON COCKLE Cerastoderma edule (Linnaeus, 1758) IN RIA DE AVEIRO, PORTUGAL
    Publication . Maia, Francisco; Ruano, Francisco; Gaspar, Miguel; Instituto Português do Mar e da Atmosfera, I.P.
    The common cockle (Cerastoderma edule) is currently the most important shellfish resource exploited in Ria de Aveiro. In recent years, surveys have been conducted by the Portuguese Institute of the Sea and Atmosphere to provide data on stock status for management purposes. The present work presents the results of the 2019 cockle survey, as well as the stock trends over the years. Results revealed that Cerastoderma edule is well established in all fishing areas of the Ria de Aveiro. The major cockle beds were found in Cale da Moacha (1951.0 g/m2 at 2.5 m depth), Mira Channel (1519.4 g/m2 at 3.4 m depth) and Ílhavo Channel (1192.8 g/m2 at 2.0 m depth). These three production areas were responsible for about 60% of the total cockle biomass caught. However, the cockle fishing yields were still remarkably lower than those registered in the 2007 survey, which may compromise the sustainability of the stocks and seriously jeopardize future catches and incomes
    2021-06-21Texto Acesso aberto Ver mais
  • CICLO REPRODUTIVO, ÍNDICE DE CONDIÇÃO E TAMANHO DE PRIMEIRA MATURAÇÃO SEXUAL DA AMÊIJOA-JAPONESA Ruditapes philippinarum (ADAMS & REEVE, 1850) NA RIA DE AVEIRO, PORTUGAL
    Publication . Maia, Francisco; Instituto Português do Mar e da Atmosfera
    This study reports the reproductive cycle, condition index and the size at first maturity of the Manila clam Ruditapes philippinarum in Ria de Aveiro (Portugal). The reproductive cycle was monitored over 1-year period, from January to December 2013, and the development of the gonads was classified into six successive maturity stages according with the microscopic observation of histological sections of the gonads. Spawning extended from April to October, with a peak by the end of summer (August and September). The condition index showed a distinct seasonal pattern which appear to be related to the reproductive cycle. The size at first sexual maturity was attained at a shell length of 20.0 mm, within the first year of life. Additionally, the reproductive strategy and the growth parameters were compared between the Manila clam and its congeneric native species the Grooved carpet shell clam (Ruditapes decussatus).
    2019Texto Acesso aberto Ver mais