Slippery customers for conservation: Distribution and decline of anguillid eels in South Africa

Four anguillid eel species occur in the western Indian Ocean rivers of Africa: Anguilla bengalensis, bicolor, marmorata and mossambica. These catadromous fishes face multiple stressors, including habitat alteration deterioration, barriers to migration, pollution adverse impacts alien species, but knowledge occurrence, abundance ecology Africa remains poor. This study investigated present historical distribution eels potential associated drivers declines at southern extremities their ranges South Africa. Data analysed included sampling conducted KwaZulu–Natal Eastern Cape between 2015 2020, secondary data extracted from databases, museums local management agencies. The median extent inland penetration increased as follows: 22 km for A. 29 marmorata, 94 bengalensis 293 altitude followed a similar pattern. Extent occurrence analyses were carried out regional level KwaZulu–Natal. on (2015–2020), compared with data, suggests extents four KwaZulu–Natal, ranging 31 48% last 30 years 35 82% since 1950s. With increasing human threats region, especially watercourse modification water abstraction, further these are expected. Conservation measures recommended include maintenance or restoration ecological connectivity important implementation freshwater protected areas. Although not widely exploited Africa, there is need fisheries regulations manage sustainable commercial exploitation.