Assessing the effect of tagging and the vulnerability to predation in tigerfish (Hydrocynus vittatus, Castelnau 1861) in a water-stressed system using telemetry methods

Koedoe - African Protected Area Conservation and Science

Field Value
Title Assessing the effect of tagging and the vulnerability to predation in tigerfish (Hydrocynus vittatus, Castelnau 1861) in a water-stressed system using telemetry methods
Creator Sonamzi, Bayanda Burnett, Matthew Petersen, Robin O'Brien, Gordon Downs, Colleen T.
Subject Ecology; Behaviour; Conservation; Ecosystem Health fish behaviour; conservation; ecological indicators; environmental stressors; e-flows; fish recovery
Description Increase in anthropogenic pressures on freshwater ecosystems, globally and locally in South Africa, has made it difficult to meet environmental flow requirements and maintain these systems. The Letaba-Olifants catchment is one such example, where the upstream water demands place pressure on the river downstream as it flows through the Kruger National Park. We used the activity rates of Hydrocynus vittatus as a line of evidence to assess (1) the effects of telemeter tagging on their activity rates in three potential post-tagging recovery periods and (2) their vulnerability to predation and the causality related to the environmental stressors placed on the river catchment in the Olifants River Gorge, Kruger National Park, South Africa. We determined H. vittatus activity rates as locomotive movement using radio telemetry methods linked remotely to an online data management system. We telemeter tagged nine individuals from 08 May to 28 June 2018. However, only seven fish were successfully tracked for the duration of our study, and two individuals moved out of range of the remote network shortly after release and could not be located. The tagged H. vittatus individuals were found to have reduced activity at least within the first 7 days after tagging compared with the time after that. The results showed that three individuals were preyed on by predators after the tagging procedure recovery period. This coincided with abnormal low flow conditions, where the Letaba River ran dry. African fish eagles Haliaeestus vocifer were the only confirmed predator, whilst predation by other species was also evident.Conservation implications: Monitoring of H. vittatus using telemetry is a viable tool to use when assessing environmental stressors in remote locations. The abnormally low water levels in the Olifants and Letaba Rivers (cessation of flow in the Letaba River) during our study may have compromised the predator avoidance strategies of tagged H. vittatus and may further be affecting the viability of the H. vittatus populations in Kruger National Park. The synergistic effects of natural and anthropogenic stressors impact negatively H. vittatus populations and potentially other aquatic biotas.
Publisher AOSIS Publishing
Contributor Water Accelerator Programme (WADER) (ZA) Water Research Commission (ZA) National Research Foundation (ZA) University of Mpumalanga (ZA) University of KwaZulu-Natal (ZA) Idea-Wild (USA)
Date 2020-12-17
Type info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion — Telemetry
Format text/html application/epub+zip text/xml application/pdf
Identifier 10.4102/koedoe.v62i1.1649
Source Koedoe; Vol 62, No 1 (2020); 12 pages 2071-0771 0075-6458
Language eng
Coverage Africa; Protected areas — Activity
Rights Copyright (c) 2020 Bayanda Sonamzi, Matthew Burnett, Robin Petersen, Gordon O'Brien, Colleen T. Downs