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Krakstad, Jens-Otto; Amaro, Aristóteles P. da S.; Shigwedha, Vaino. |
The main objectives of the survey were the following: • To map the distribution and estimate the abundance of the most commercially important pelagic species in the Namibia-Angola transboundary area (15°50-19°00’), following the survey design utilized in Angolan waters (6 n.mi spacing between transect lines), with special emphasis on the two horse mackerel Cunene horse mackerel (Trachurus trecae) and Cape horse mackerel (Trachurus capensis), sardine “Pilchard” (Sardinops sagax) and other small pelagic species, including anchovy (Engraulis capensis) and round herring (Etrumeus whiteheadi). • To map the distributions and estimate the abundance of the same species in central Namibia south to Dune Point (20°15’ S), following the established survey design with... |
Tipo: Report |
Palavras-chave: Pelagic fisheries; Fishery surveys; Acoustics; Sampling; Trawls; Oceanography; Biomass; Distribution; Composition. |
Ano: 2012 |
URL: http://hdl.handle.net/1834/5230 |
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Denis Tweddle; Eric Anderson. |
Collections of fishes from demersal trawl surveys to 800 m depth off the Angolan coast in 2001, 2002 and 2005 resulted in several range extensions tabulated here. Specimens of species poorly represented in previous collections allowed improved diagnoses of Myxine ios, Torpedo bauchotae, Dysommina rugosa, Pisodonophis semicinctus, Xenomystax congroides, Lestidiops cadenati, Ophidion lozanoi, Cataetyx bruuni, Dibranchus atlanticus, Diceratias pileatus, Himantolophus paucifilosus, Neomerinthe folgori, Careproctus albescens, Paracaristius maderensis and Pachycara crossacanthum. All specimens accessioned into the Fish Collection of the South African Institute for Aquatic Biodiversity are listed and colour plates show a selection of species from the trawl catches |
Tipo: Journal Contribution |
Palavras-chave: Demersal fish; Trawls; Fish species; Marine fish. |
Ano: 2007 |
URL: http://hdl.handle.net/1834/5148 |
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Koranteng, K.A.. |
Between 1963 and 1990, the abundance of demersal fishery resources in Ghana’s shelf waters underwent significant changes whereby the relative importance of major species changed in every trawl survey conducted in the area. Triggerfish (Balistes capriscus) dominated this ecosystem for nearly twenty years (from early 1970s to late 1980s) displacing bigeye grunt (Brachydeuterus auritus) as the most abundant species.The density of all demersal species (excluding triggerfish) assessed in bottom trawl surveys decreased from 50 kg ha-1 in 1963-64 to 32.4 kg ha-1 in 1990. The lowest density of 22.5 kg ha-1 occurred between 1973 and 1977. Density of triggerfish was high between 1973 and 1982, reaching a value of 28 kg ha-1 between depths of 30 and 50 m. Its... |
Tipo: Journal Contribution |
Palavras-chave: Demersal fisheries; Trawls; Fishery surveys. |
Ano: 2001 |
URL: http://hdl.handle.net/1834/241 |
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