AEI prepress abstract  -  DOI: https://doi.org/10.3354/aei00313

Relationships between off-bottom bivalve aquaculture and the Magellanic steamer duck Tachyeres pteneres in southern Chile

Gonzalo Medina-Vogel*, Daniel J Pons, Roberto P Schlatter†

*Email: gmedina@unab.cl

ABSTRACT: Interactions between aquaculture farms and endemic marine birds in the Northern Hemisphere have become a recurrent topic in the past decades. In this scenario, shellfish aquaculture farms lead to diverse effects on wildlife populations; on the other hand, the substantial predation on mussels by birds leads to a control of the birds by the managers. In this work we assess the interaction between Chilean blue mussel Mytilus edulis chilensis farms and the Magellanic steamer duck Tachyeres pteneres, an endemic duck of Southern Chile whose population is thought to be declining along all its distributions. In particular, we assess the importance of the Chilean blue mussel in the Magellanic steamer duck´s diet, and we estimate the magnitude of the losses from the aquaculture due to predation by the ducks. Between March 1988 and February 1989, observations and sampling collections were performed around a bivalve aquaculture farm in Yaldad Bay (Chiloé Island, Chile). In contrast to what happens in the Northern Hemisphere, we infer that Chilean blue mussel farms do not promote the increase of Magellanic steamer duck populations: the population dynamics seem to be responding to other habitat variables. Moreover, our estimate for the losses due to predation yield less than 1.6% of the farming annual production. Despite the fact that sampling was done before 1989, this study is the most recent one for the ecology and social behaviour of Magellanic steamer duck and for its relationship with the bivalve aquaculture.