Versatile Tuna Hotels

RiverCare’s ‘Tuna Hotels’ are re-purposed weed trees placed to create in-lake structure for birds, fish and insects.

In 2017, RiverCare carried out a small-scale trial with brush piles at Lake Ohinewai with localised benefits noticed almost immediately for lake wildlife.

In 2020, RiverCare started the Lake Ohinewai Recreational Reserve Wetland Restoration Project in partnership with the Waikato District Council and Waikato River Authority. Targeted funding provided the perfect opportunity to expand the available habitat and build on the excellent research work already undertaken by freshwater scientists from the Waikato Regional Council.

Instead of cutting down and burning the weed trees (Australian gum and shrubby wattle) on our planting project; the tree trunks were transported to the edge of Lake Ohinewai where a digger carefully placed the material to create five new tuna hotels (brush piles).

Lake Ohinewai is a peat lake with a soft, muddy bottom; it doesn’t contain a lot of structure (underwater reefs or large woody logs) which are critical for many fish and insect communities. The brush piles are a cost effect solution to providing this much needed habitat and helping our fight against climate change by capturing and storing atmospheric carbon dioxide within the tree’s timber (carbon sequestration).

The tuna hotels are especially beneficial during the summer months as they provide critical overhead cover during long-hot days when ‘in lake’ anoxic conditions (no oxygen in the water) occur forcing fish to the lake’s edge making them vulnerable to predation and the effects of solar radiation… it is the tuna’s shade bathing spot!