Abstract
Hydrocynus vittatus Castelnau, 1861, commonly known as tigerfish, is a flagship species
widely distributed in the North Eastern region of South Africa, and are easily identified by the
public. This species is actively targeted and utilised by angling and subsistence fishing
communities and also used as indicator species by resource and water quality managers to
transfer ecosystem related information to the public. Tigerfish therefore has a high
ecological, economical and social value to South Africans. Unfortunately, they are lost
through habitat changes caused by water extraction, pollution and obstructions like dams
and weirs. Tigerfish depend greatly on the available natural habitats to breed, feed and
function appropriately. A slight change in the environment may cause depletion of the overall
population. Tigerfish are considered rare in South Africa and are classified as a protected
species. Scientific studies of all aspects of tigerfish biology are therefore vitally important to
understand what quality habitat is required for its successful survival. This information is
necessary to development a conservation plan for tigerfish in South Africa. The ecological
and economic importance and current conservation status of the tigerfish lead to the current
project undertaken by researchers from the Centre for Aquatic Research (CAR) in the
Department of Zoology, University of Johannesburg and Water Research Group (WRG),
Unit for Environmental Sciences and Management, North West University.
Historically tigerfish were prevalent in all 6 major rivers in the Kruger National Park
(KNP) and areas on the western border of the Park. Recent surveys have shown that the
distribution of this protected species is drastically reduced. The development of a
management strategy to protect tigerfish within the Kruger National Park rivers is therefore
of utmost importance. As a top predator tigerfish bio-magnifies pollutants and the risk that
these pollutants pose are greater to them than to the lower trophic levels. A single study on
metal levels in the Olifants River is the only information on levels of contamination in
tigerfish. The levels of organic and inorganic substances together with the information on
population structures and reproductive status will provide valuable insight into whether
exposure to these contaminants has an influence on the general health of tigerfish
populations in the KNP. This study addressed all the factors that might influence the health
and conservation status of tigerfish. The upper catchments of all the rivers that run through
the KNP are subjected to mining as well as intensive agricultural activities with high
contamination potential. This tigerfish project was conducted on request from the KNP
Scientific Services who identified the management of tigerfish within the borders of the KNP
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as a conservation priority. The study dealt with questions on the sufficiency of the current
ecological water allocation for the Olifants River in terms of aquatic species requirements in
the system as well as individual and population health.