Articles by Author: A Almeida

Search results for A Almeida

We found 9 results for you
  1. Bush control in grassland by aerial spraying

    Bush control in grassland by aerial spraying

    The results are reported of three trials in which chemicals were applied from an aircraft to control bush on severely infested natural grassland in Moçambique. Acacia nilotica, A. borleae and Dichrostachys cinerea were killed by a mixture of 2,4‐D and...
  2. Comparison of horse mackerel length frequencies obtained from research vessels and commercial midwater trawlers: implications for biomass estimation

    Comparison of horse mackerel length frequencies obtained from research vessels and commercial midwater trawlers: implications for biomass estimation

    Item type: Journal Article • Journal: South African Journal of Marine Science
    The validity of abundance estimates from hydroacoustic surveys relies, inter alia, on the ability of the fishing gear on the research vessel to sample non-selectively. This study compares the length frequencies of Cape horse mackerel Trachurus trachurus capensis taken in...
  3. <em>In Situ</em> Measurements of the Acoustic Target Strength of Cape Horse Mackerel <em>Trachurus Trachurus Capensis</em> Off Namibia

    <em>In Situ</em> Measurements of the Acoustic Target Strength of Cape Horse Mackerel <em>Trachurus Trachurus Capensis</em> Off Namibia

    Item type: Journal Article • Journal: African Journal of Marine Science
    The acoustic target strength (TS) of Cape horse mackerel Trachurus trachurus capensis was measured in situ at 38 kHz during two surveys over the Namibian continental shelf in 1998 and 1999 using a SIMRAD EK500 echosounder/ES38D submersible split-beam transducer. Scattered...
  4. Identification of acoustic targets off Angola using General Discriminant Analysis

    Identification of acoustic targets off Angola using General Discriminant Analysis

    Item type: Journal Article • Journal: African Journal of Marine Science
    Pelagic fish off Angola constitute about 80% of the total fish landed and some 75% of the animal protein in the diet of the coastal population. The primary means of estimating stock abundance is through acoustic surveys, a method that...
  5. Assessment and management of Cape horse mackerel <em>Trachurus capensis</em> off Namibia based on a fleet-disaggregated age-structured production model

    Assessment and management of Cape horse mackerel <em>Trachurus capensis</em> off Namibia based on a fleet-disaggregated age-structured production model

    Item type: Journal Article • Journal: African Journal of Marine Science
    The Cape horse mackerel stock off Namibia is assessed using a fleet-disaggregated age-structured production model including historical International Commission for the Southeast Atlantic Fisheries (ICSEAF) and current data. Data from acoustic biomass surveys, on commercial catch per unit effort and...
  6. Ecological distribution of the shrimp <em>Nematopalaemon schmitti</em> (Crustacea: Decapoda: Caridea) in three bays on the south-eastern coast of Brazil

    Ecological distribution of the shrimp <em>Nematopalaemon schmitti</em> (Crustacea: Decapoda: Caridea) in three bays on the south-eastern coast of Brazil

    Item type: Journal Article • Journal: African Journal of Marine Science
    The relationships between the spatial and temporal variations in the abundance of the shrimp Nematopalaemon schmitti and water temperature, salinity, and texture and organic-matter content of the sediment, were analysed in Ubatumirim, Ubatuba and Mar Virado bays on the northern...
  7. New evidence for a South Atlantic stock of humpback whales wintering on the Northwest African continental shelf

    New evidence for a South Atlantic stock of humpback whales wintering on the Northwest African continental shelf

    Item type: Journal Article • Journal: African Zoology
    Seventeen confirmed and four probable sightings of humpback whales, Megaptera novaeangliae, were documented from platform-of-opportunity Research Vessel (R/V) Dr. Fridtjof Nansen in a passing-mode visual survey of continental shelf waters between Conakry and Cap Vert Peninsula (Dakar), 21 October -5...
  8. Hypoxia adaptation in fish of the Amazon: a never-ending task

    Item type: Journal Article • Journal: South African Journal of Zoology
    In addition to seasonal long-term changes in dissolved oxygen and carbon dioxide, water bodies of the Amazon present periodic short-term episodes of hypoxia and even anoxia. To preserve gas exchange and acid base balance, fish of the Amazon have developed...
  9. Predatory pelagic fishes of the Bijagós Archipelago (Guinea-Bissau) show high overlap in diets dominated by sardinella

    Predatory pelagic fishes of the Bijagós Archipelago (Guinea-Bissau) show high overlap in diets dominated by sardinella

    Item type: Journal Article • Journal: African Journal of Marine Science
    Knowledge of trophic interactions between the key components of marine communities is required to understand food-web dynamics and develop ecosystem-based management approaches. In West Africa, where fisheries sustain the livelihoods of a significant part of the human population, this understanding...