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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 • Authors: G. Bauleth-D'Almeida J-O. Krakstad A. KanandjemboThe 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... -
Population genetic studies of horse mackerel Trachurus trecae and Trachurus trachurus capensis off Angola
Item type: Journal Article • Journal: South African Journal of Marine Science • Authors: M. I. Sardinha G. NævdalGenetic variability of the Kunene horse mackerel Trachurus trecae and the Cape horse mackerel Trachurus trachurus capensis was examined using starch gel electrophoresis of enzymatic proteins on individuals collected along the Angolan coast. Six polymorphic enzyme loci were found in... -
In Situ Measurements of the Acoustic Target Strength of Cape Horse Mackerel Trachurus Trachurus Capensis Off Namibia
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: B. E. Axelsen G. Bauleth-D'Almeida A. KanandjemboThe 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... -
Vertical migration, catchability and acoustic assessment of semi-pelagic Cape horse mackerel Trachurus trachurus capensis in the southern Benguela
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: M Barange SC Pillar I Huse L HutchingsThe vertical distribution and migration of the Cape horse mackerel Trachurus trachurus capensis were investigated on the basis of midwater and bottom trawl collections taken over diel cycles at two sites on South Africa's south coast. Attempts were also made... -
A Bayesian state-space model for mixed-stock migrations, with application to Northeast Atlantic mackerel Scomber scombrus
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: CL Cunningham DG Reid MK McAllister GP Kirkwood CD DarbyManagement of fisheries that exploit mixed-stock populations relies on assumptions made concerning stock structure and mixing in different areas. To address the problems of accounting for uncertainty when formulating scientific advice for the management of highly migratory fish stocks, management... -
A review of the assessments of the major fisheries resources in South Africa
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: CL de Moor --- Marine Resource Assessment and Management Group (MARAM), Department of Mathematics and Applied Mathematics, South Africa SJ Johnston --- Marine Resource Assessment and Management Group (MARAM), Department of Mathematics and Applied Mathematics, South Africa A Brandão --- Marine Resource Assessment and Management Group (MARAM), Department of Mathematics and Applied Mathematics, South Africa RA Rademeyer --- Marine Resource Assessment and Management Group (MARAM), Department of Mathematics and Applied Mathematics, South Africa JP Glazer --- Branch: Fisheries Management, Department of Agriculture, South Africa LB Furman --- Marine Resource Assessment and Management Group (MARAM), Department of Mathematics and Applied Mathematics, South Africa DS Butterworth --- Marine Resource Assessment and Management Group (MARAM), Department of Mathematics and Applied Mathematics, South AfricaThe waters off South Africa's coastline boast a rich mix of commercially fished species. Quantitative assessments of these marine resources have developed from simple methods first applied in the 1970s, to models that encompass a wide range of methodologies. The... -
Pelagic eggs of marine fishes from Park Rynie, KwaZulu-Natal, South Africa: seasonal spawning patterns of the three most common species
Item type: Journal Article • Journal: African Zoology • Authors: A.D. Connell --- Environmentek, South AfricaFor the period 1987 to 1998, pelagic eggs of marine fishes were collected from shelf waters at Park Rynie on the KwaZulu-Natal south coast. The three most numerous eggs collected were those of the mackerel Scomber japonicus,the sardine Sardinops sagax... -
Geographical and seasonal patterns in the diet of Cape fur seals Arctocephalus pusillus pusillus in Namibia, based on extensive scat analyses
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: DN Mwaala --- University of Namibia, Namibia MR Wilhelm --- University of Namibia, Namibia SP Kirkman --- Fisheries and the Environment (DFFE): Branch Oceans and Coasts, South Africa J-P Roux --- Ministry of Fisheries and Marine Resources, NamibiaNamibia's population of Cape fur seals Arctocephalus pusillus pusillus is a major constituent of top predator biomass in the northern Benguela upwelling system. Understanding their diet is key to comprehending their role in the ecosystem and potential drivers of recent...