Original Research

A survey of the ichthyofauna in the Noetsie Estuary, Western Cape Province, South Africa

Martin K.S. Smith, Demi Rodrigues, Bianca Currie
Koedoe | Vol 60, No 1 | a1513 | DOI: https://doi.org/10.4102/koedoe.v60i1.1513 | © 2018 Martin K.S. Smith, Demi Rodrigues, Bianca Currie | This work is licensed under CC Attribution 4.0
Submitted: 18 December 2017 | Published: 16 July 2018

About the author(s)

Martin K.S. Smith, Rondevlei Scientific Services, South African National Parks, South Africa
Demi Rodrigues, School of Natural Resource Management, Nelson Mandela University, South Africa
Bianca Currie, Sustainability Research Unit, Nelson Mandela University, South Africa


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Abstract

The fish assemblage in the Noetsie Estuary, a temporarily open and closed estuary on the southern coast of South Africa, was sampled using multiple gears. A total of 12 species from 8 families were recorded. Collectively, estuarine-dependent marine species dominated seine net catches numerically and in terms of biomass for both sampling seasons. Estuarine round herring (Gilchristella aestuaria) was numerically the dominant species in late summer, while juvenile Mugilidae dominated catches in winter. Size class distributions of various fish species indicate that the estuary both serves a nursery function for important euryhaline marine species and supports estuarine resident taxa. Application of the Estuarine Fish Community Index indicates the ecological condition of the estuary to be ‘good’. This study contributes to the species list for the estuary while also reporting the presence of an alien invasive freshwater species, Gambusia affinis. Recommendations include the development of a management plan and the formalisation of an estuarine management committee.

Conservation implications: The Noetsie Estuary serves a nursery function for important euryhaline marine species, while supporting healthy populations of estuarine resident taxa. The presence of one alien invasive fish species is documented with potential implications for the conservation of biodiversity in the estuary.

Keywords

fish community; temporarily open/closed estuary; alien invasive fish

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