Articles by Author: Colin Attwood

Search results for Colin Attwood

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  1. Chondrichthyan occurrence and abundance trends in False Bay, South Africa, spanning a century of catch and survey records

    Chondrichthyan occurrence and abundance trends in False Bay, South Africa, spanning a century of catch and survey records

    Item type: Journal Article • Journal: African Zoology
    Commercial fishing in False Bay, South Africa, began in the 1600s. Today chondrichthyans are regularly taken in fisheries throughout the bay. Using a combination of catch, survey and life history data, the occurrence and long-term changes in populations of chondrichthyans...
  2. ULTRA-UNIVERSAL MODELS

    ULTRA-UNIVERSAL MODELS

    Item type: Journal Article • Journal: Quaestiones Mathematicae
    The concept of ultra-universal algebras in varieties is generalized to models of first order theories. Characterizations of theories which have ulta-universal models are found and general examples of ultra-universal models are investigated. In particular we show that a theory has...
  3. COUNTABILITY PROPERTIES IN INTERIOR ALGEBRAS

    COUNTABILITY PROPERTIES IN INTERIOR ALGEBRAS

    Item type: Journal Article • Journal: Quaestiones Mathematicae
    Certain topological countability properties are generalized to interior algebras and basic reaults concerning these properies are investigated. The preservation of these properties under the formation of principal quotients and under a new construction called a join of interior algebras, is...
  4. Discrepancy between otolith and tag-recovery estimates of growth for two South African surf-zone teleost species

    Discrepancy between otolith and tag-recovery estimates of growth for two South African surf-zone teleost species

    Item type: Journal Article • Journal: South African Journal of Marine Science
    Growth rates determined from recovered tagged galjoen Dichistius capensis and white steenbras Lithognathus lithognathus were compared to predictions from growth models based on otolith ring counts. Galjoen could not be sexed externally, but it was assumed that all fish >450...
  5. Nearshore surface current patterns in the Tsitsikamma National Park, South Africa

    Nearshore surface current patterns in the Tsitsikamma National Park, South Africa

    Item type: Journal Article • Journal: South African Journal of Marine Science
    The pattern of surface currents in the Tsitsikamma National Park, South Africa, was studied with holey-sock drogues released in batches of up to four at a time, from 1996 and 1998. Drogues were left to drift for either 6 or...
  6. A simulation model of the sport-fishery for galjoen <em>Coracinus capensis</em>: an evaluation of minimum size limit and closed season

    A simulation model of the sport-fishery for galjoen <em>Coracinus capensis</em>: an evaluation of minimum size limit and closed season

    Item type: Journal Article • Journal: South African Journal of Marine Science
    An age-structured stochastic simulation model is used to evaluate minimum size limit and closed season restrictions in terms of yield, effort and stock size for the sport-fishery for galjoen Coracinus capensis for a projected 15-year period, on the assumption that...
  7. Shore-angling catches in the De Hoop Nature Reserve, South Africa, and further evidence for the protective value of marine reserves

    Shore-angling catches in the De Hoop Nature Reserve, South Africa, and further evidence for the protective value of marine reserves

    Item type: Journal Article • Journal: South African Journal of Marine Science
    Data on the species composition, size, seasonality and capture rates of surf-zone fish sampled by shore-angling at two sites in the De Hoop Marine Reserve are presented. In all, 21 969 fish of 33 species were caught during 11 344...
  8. Teleost catches by three shore-angling clubs in the South-Western Cape, with an assessment of the effect of restrictions applied in 1985

    Teleost catches by three shore-angling clubs in the South-Western Cape, with an assessment of the effect of restrictions applied in 1985

    Item type: Journal Article • Journal: South African Journal of Marine Science
    The species composition, catch rates and size composition of teleost species in catches made between 1938 and 1992 by three shore-angling clubs in the South-Western Cape are described. Numerically, Lithognathus lithognathus (29,45%), Dichistius capensis (24,69%), Diplodus sargus (12,92%), Argyrosomus hololepidotus...
  9. A procedure for setting daily bag limits on the recreational shore-fishery of the South-Western Cape, South Africa

    A procedure for setting daily bag limits on the recreational shore-fishery of the South-Western Cape, South Africa

    Item type: Journal Article • Journal: South African Journal of Marine Science
    Individual daily catch records are used to devise a method to estimate the fraction of the recreational catch that can be prevented by a daily bag limit (DBL). This fraction is interpreted as a potential reduction of fishing mortality. The...