Trade and socioeconomic importance of an invasive giant snail in the endemic-rich island of São Tomé, Central Africa

Abstract

Managing invasive species is crucial to mitigate their negative impacts on ecosystems, yet conflicts may arise when their social benefits are disregarded. Human pressure on the endemic-rich forests of São Tomé has been high since the island was discovered by the Portuguese in the 15th century, and numerous species have been introduced. These include the invasive West African giant land snail (Archachatina marginata), which was introduced in the mid-20th century, is now widespread on the island, and is a potential threat to native flora and fauna. We assessed the frequency of consumption of this species and its socioeconomic importance to people across the island with household questionnaires, focus group discussions, and semistructured interviews. We explored the prevalence and potential drivers of use (e.g., wealth, household composition, and diversity of occupations) and characterized the commodity chain to identify demographic groups linked to the snail trade. We interviewed 672 people (1 person per household), conducted 6 focus groups, and interviewed 80 key actors belonging to 5 subcategories. The snail was the most widely consumed bushmeat and an important source of income, particularly for women and unemployed youth. Insecure and scarce livelihood alternatives, mostly in rural areas, were reported as drivers for trade involvement. Snail harvesting was more frequent in poorer households with low occupational diversity. Selling tended to occur in households that were well-established in the community and had a higher proportion of children. Both were stimulated by the proximity of communities to the native forest. Buying snails was common in all demographic groups, but it was linked to wealth and occupational diversity. Interventions to manage the impact of this introduced species on the valuable ecosystems of the island should involve multiple sectors of society to ensure societal support. This requires robust consideration of the welfare of vulnerable demographic groups that benefit from the species.