An evaluation of the current extent and potential spread of Black Bass invasions in South Africa

Abstract

Black Bass, a collective name for members of the centrarchid genus Micropterus, are native to North America, but have been introduced globally to enhance recreational angling. This study assessed the distribution of Micropterus salmoides, M. dolomieu and M. punctulatus in South Africa using both formal (survey-based) and informal (tournament data and social media) information sources. Analysis of the distribution data showed habitat bias between the data sources. Survey data from formal information sources were dominated by locality records in riverine environments while those derived from informal information sources focused more on lacustrine habitats. Presence data were used to develop niche models to identify suitable areas for their establishment. The predicted distribution range of M. salmoides revealed a broad suitability over most of South Africa, however, the Cape Fold Ecoregion and all coastal regions were most suitable for the establishment for both M. dolomieu and M. punctulatus. Flow accumulation and precipitation of coldest quarter were the most important environmental variables associated with the presence of all Black Bass species in South Africa. In addition, anthropogenic disturbance such as Electronic supplementary material The online version of this article (

An Evaluation of the Impacts of Alien Species on Biodiversity in South Africa Using Different Assessment Methods

“…Black bass is the collective name for species of the genus Micropterus which, in South Africa, includes M. salmoides, M. dolomieu, M. punctulatus (Spotted Bass) and M. floridanus (Florida Bass) (Weyl et al 2017b). As warm water species, Black Bass were introduced for sport fishing in the lower reaches of rivers and impoundments (see Khosa et al 2019). Their impacts are similar to those documented for O. mykiss and S. trutta, and include the alteration of invertebrate communities (Weyl et al 2010) and local extirpations and fragmentation of native fish populations (e.g.…”

Alien Freshwater Fauna in South Africa

“…Its reproduction includes the construction and defence of shallow-water nests in spring with males guarding eggs, larvae and fry. As a result of its affinity for vegetated still waters, it is common in slower sections of all larger rivers and in impoundments (Khosa et al 2019).…”

“…Micropterus dolomieu, which have an affinity for flowing water, were introduced from the USA in 1937 and M. punctulatus in 1939 for stocking in rivers too turbid to suit M. dolomieu (see . Although not as widespread as M. salmoides and M. floridanus, M. dolomieu and M. punctulatus have invaded parts of many river systems in the Eastern and Western Cape (Khosa et al 2019).…”

“…Most severe are the impacts on native minnows that have not coevolved with native predatory fishes (Ellender et al 2018). For example, in the Olifants River system in the Western Cape, predation has fragmented native minnow populations to such an Skelton and Weyl 2011;Marr et al 2018;Khosa et al 2019) extent that most species now only persist in headwater refugia that are isolated from black bass invasion by the presence of waterfalls (van der Walt et al 2016). This has reduced the available habitat for native fishes in the Olifants-Doring River system by more than 700 km of river (van der Walt et al 2016).…”

Resilience Management for Conservation of Inland Recreational Fisheries

“…Many sport fishes, including several black bass (Micropterus) species have been stocked into South Africa's freshwater systems for the improvement of recreational angling opportunities (Ellender and Weyl, 2014). Smallmouth bass Micropterus dolomieu were introduced into South Africa in 1937 and rapidly established themselves in several freshwater systems (Khosa et al, 2019). Although this encouraged the development of recreational angling, which makes an important economic contribution to the South African Economy (Saayman et al, 2017), this species has resulted in the extirpation of endemic fishes (Van Der Walt et al, 2016).…”