Horse Mussels

Dense horse mussel bed near Pakiri. Photo by NIWA 1996.

Horse mussels / Hururoa (Atrina zelandica) are the largest shellfish in Aotearoa New Zealand. Their large shells create habitats that shelter juvenile fish and provide food for adult fish. Horse mussels are also giant pumps that clean the water while feeding. Dense beds of horse mussels once carpeted large areas of the seafloor. In the Hauraki Gulf beds were big enough to tear nets being dragged over them. To address this problem, fishermen dragged ship chain between two steam trawlers and smashed up the horse mussels and other complex habitats. Much of the seafloor became a muddy ‘paddock’. Remanent beds persisted into the 1990s and individual horse mussels can still be found today.

Science for Nature has commissioned surveys to determine if there are still beds in the Hauraki Gulf as a platform for restoration. We have also offered prizes to citizen scientists to locate horse mussel beds (see link below).