RRC ID 70666
Author Lerato T. Maimela, Christian T. Chimimba, Tsungai A. Zengeya
Title The legacy of over a century of introductions: Spread debt of rainbow trout (Oncorhynchus mykiss) in Mpumalanga Province, South Africa
Journal River Research and Applications
Abstract For over a century, rainbow trout (Oncorhynchus mykiss) has been widely introduced into lakes and rivers in South Africa to create and enhance sport-fishing opportunities. Despite its long history of introduction, naturalized populations of rainbow trout are still localized to a few areas with suitable habitats and climate. This study assessed the spread debt (i.e., the increase in area invaded by invasive species over time) of rainbow trout in Mpumalanga Province, South Africa to highlight areas with known introductions, the extent of the invasion, and to identify areas that are suitable for establishment but are still invasion-free. The total river length that was predicted as suitable for rainbow trout under current climate was about ca. 3,500 km in an extension of about ca. 15,000 km. Current occupancy (river length predicted as suitable with known rainbow trout occurrence records) was ca. 1,220 km (35%) and the invasion debt was therefore estimated as 65%. While these data infer a large invasion debt, they are confounded by a lack of knowledge on sampling effort and verified true absence and should therefore be recognized as an estimate. In addition, the extent of the suitable area varied under different climate change scenarios where it was projected to decrease under RCP 4.5 scenarios and increase under the RCP 8.5 scenarios. This study demonstrates some of the difficulties of quantifying the potential future extent and impacts of biological invasions and how the invasion debt concept can be applied to provide an important link between invasion biology, management, and policy.
Published 2022-4-19
DOI 10.1002/rra.3976
Resource
GBIF Freshwater Fish specimens of Taga Town Museum, Shiga Pref., Japan Freshwater Fish Specimens of Lake Biwa Museum Gunma Museum of Natural History, Fish Specimen Ibaraki Nature Museum, Fish collection Actinopterygius Specimens of Akita Prefectural Museum Fish Specimens of Tokushima Prefectural Museum, Japan Fish collection of the Museum of Nature and Human Activities, Hyogo Fish Collection of Kanagawa Prefectural Museum of Natural History Fish specimen database of Osaka Museum of Natural History vertebrate specimens of Kumamoto City Museum