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Human-wildlife interactions on the tidal flats of the Bijagós archipelago: does shellfishing affect migratory shorebirds?

Coelho, Ana1

Published Jun 17, 2024 on Dryad. https://doi.org/10.5061/dryad.2ngf1vhtk

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Jun 17, 2024 version files 91.42 KB

Abstract

The Bijagós archipelago in West Africa is home to an ethnic group with a rich cultural heritage that is tightly linked to nature. The Bijagós people have a shared cultural identity, but across islands, there are different resource management regimes stemming from island-specific context with regards to socio-political organization and strength of cultural heritage. Across the archipelago, bivalves harvested manually from the mudflats are an important part of the Bijagós people’s diet, economy, and culture. Thousands of migratory shorebirds share the use of these mudflats during their non-breeding season, consuming macrobenthos such as crustaceans and bivalves, including those harvested by local people. At the end of their stay in the Bijagós, shorebirds need to fuel for their migratory flight in order to return to their breeding areas, being particularly important during this period that they have access to undisturbed feeding areas with suitable food resources.

In this study, we start by exploring shellfishing patterns across different management regimes, then assess seasonal variation in the direct impact of shellfishing on shorebirds (through competition for resources and space), and finally quantify the indirect impact of sediment disturbance due to shellfishing upon shorebird prey availability. Results indicate that bivalve resources are better managed in areas with formal protection, while traditional management based on cultural beliefs results in poorer stock conditions. Interestingly, across islands shellfishing activity is concentrated in mid-winter, decreasing towards shorebirds’ fuelling period, when they benefit the most from reduced disturbance on the mudflats. No direct competition for resources was detected, as collected bivalves were significantly larger than those consumed by shorebirds, regardless of the season. Indirect impacts caused by sediment disturbance during shellfishing were also mostly absent, causing only a small reduction on shorebirds prey density, but with no effect on the available biomass.