Impacts of human activities on marine animal life in the Benguela: A historical overview

Abstract

This review provides a historical overview of human activities in the Benguela and documents their effects on marine animal life. Considered are the activities of conventional industrial and inshore fisheries but also nonfishery activities, such as mariculture, regulation of river flow, introduction of marine invasive species, marine contruction and mining, pollution and climate change. Human influences may conveniently be divided into four epochs: aboriginal (c. 10,000 before present (BP)-c. 1652), preindustrial (c. 1652-c. 1910), industrial (c. 1910-c. 1975) and postindustrial (c. 1975-present). The aboriginal epoch is characterised by low levels of mainly intertidal exploitation; the preindustrial epoch by intense exploitation of few large, accessible species; the industrial epoch by technological development and a subsequent massive escalation in catches; and the postindustial epoch by improved resource management and stabilisation of catches, but increasing nonfishery impacts on the system. Over 50 million t of biomass has been extracted from the system over the past 200 yr, resulting in significant changes in community structure. Extraction rates peaked at over 1.3 million t yr-1 in the 1960s and have subsequently declined by over 50%. Populations of whales, seals and pelagic and demersal fishes are recovering from historical overexploitation, while those of inshore stocks, particularly abalone, rock lobster and inshore linefishes, remain severely depressed.