Blar i forfatter "Groeneveld, Johan C."
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Advection-diffusion models of spiny lobster Palinurus gilchristi migrations for use in spatial fisheries management
Santos, Jorge; Rouillard, Denis; Groeneveld, Johan C. (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-02-17) -
Effect of rotational harvesting on the size composition of Cape rock oysters Striostrea margaritacea on the east coast of South Africa
Steyn, Erika; Groeneveld, Johan C.; Santos, Antonio Jorge Fonseca Antunes (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-12-11)A commercial fishery for the Cape rock oyster Striostrea margaritacea along the north coast of KwaZulu-Natal, South Africa (western Indian Ocean), follows a 4-year rotational cycle, with each harvest year followed by 3 fallow years across four harvest zones. We analysed reported harvesting effort and catch information, and fishery-independent oyster size composition data collected over 18 years (Feb ... -
Effects of inconsistent reporting, regulation changes and market demand on abundance indices of sharks caught by pelagic longliners off southern Africa
Jordaan, Gareth L.; Santos, Jorge; Groeneveld, Johan C. (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-10-24)The assumption of a proportional relationship between catch-per-unit-effort (CPUE) and the abundance of sharks caught by pelagic longliners is tenuous when based on fisher logbooks that report only retained specimens. Nevertheless, commercial logbooks and landings statistics are often the only data available for stock status assessments. Logbook data collected from local and foreign pelagic longline ... -
Population structure and biology of shortfin mako, Isurus oxyrinchus, in the south-west Indian Ocean
Groeneveld, Johan C.; Cliff, G.; Dudley, S.F.J.; Foulis, A.J.; Santos, Jorge; Wintner, S.P. (Journal article; Tidsskriftartikkel; Peer reviewed, 2014) -
Shark discards in selective and mixed-species pelagic longline fisheries
Jordaan, Gareth L.; Santos, Jorge; Groeneveld, Johan C. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-08-31)The conservation status of several pelagic shark species is considered vulnerable with declining populations, yet data on shark fishing mortality remain limited for large ocean regions. Pelagic sharks are increasingly retained by mixed-species fisheries, or are discarded and not reported by selective fisheries for tunas (<i>Thunnus</i> spp.) or swordfish (<i>Xiphias gladius</i>). We estimated the ... -
Trends in a recreational fishery for mussels in eastern South Africa, based on postal, telephone and online surveys
Steyn, Erika; Groeneveld, Johan C.; Santos, Jorge; Kruger, Alke; Mselegu, Xolani I.; Schleyer, Michael H. (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-07-18)The intertidal brown mussel <i>Perna perna</i> is targeted by recreational and subsistence fisheries in KwaZulu-Natal, South Africa. The recreational mussel fishery is monitored by off-site postal, telephone and online questionnaire surveys, assessed in this study. Trends in fisher avidity (proportion of permit holders that went fishing), mean number of outings undertaken per quarter year and catch ...