Native fish monitoring
Fish monitoring in the Groot River estuary aims to determine both the structural and functional properties of the estuary’s fish community. As a continuation of an earlier study conducted by SANParks, seine netting is still practised quarterly with the result that the NVT currently holds the best estuary fish dataset in the Western Cape. Given that the Groot River estuary is a temporarily open/closed system, ongoing monitoring can be indicative of the estuary’s ecological condition and provide for better management strategies.
Alien fish monitoring
Given that an alien fish species (the invasive Western Mosquitofish) has been introduced to the Groot River estuary, it is necessary to assess how this has affected endemic species and, ultimately, species composition so that direct pressures on native species, if any, can be managed and alleviated. Monthly sampling at 11 sites for Western Mosquitofish revealed seasonal patterns of abundance, and potential hotspots or refugia that sustain this species. Data collected over a span of four years is currently being analysed and will be subjected to peer review before being published. It is anticipated that the outcome of this study will aid the relevant authorities in taking decisions on how best to manage the estuary.