Evidence for overfishing of tigerfish Hydrocynus vittatus (Castelnau 1861) in the Kavango River, Namibia

Abstract

The fishery for the African tigerfish Hydrocynus vittatus in northern Namibia makes a substantial contribution to surrounding food security and stimulates the local economy through subsistence and recreational fishing. However, local fishers suggest that catch rates of H. vittatus have declined and the fish are now smaller. The Namibian Ministry of Fisheries and Marine Resources conducted annual gill net surveys in the Kavango River from 1994 to 2018. These standardised surveys were used to compare catch per unit effort data and length frequencies of H. vittatus between intensively fished areas and a freshwater protected area (FPA). The catch per unit effort (by numbers and mass) and proportion (56% vs 10–20%) of mature fish (males >180 mm fork length and females >280 mm fork length) were higher inside the FPA, compared with those outside. The H. vittatus populations, both outside and inside the FPA, are subject to overfishing and management actions should be taken to secure this important fishery resource for subsistence and recreational fishers.

Keywords:

• catch per unit effort
• freshwater protected area
• inland fisheries
• length frequency
• sustainable management