The pā tuna (eel weir) was a common device for catching eels in rivers, streams and the outlets of lagoons and lakes. Weirs were used in autumn, to catch eels as they headed downstream to spawn in the sea. Fences in the water guided the eels into a net and then into a hīnaki (eel pot). Pā tuna were useful when rivers were in flood or flowing heavily.
Eels run mostly at night, so people sometimes stayed up to empty the hīnaki as they filled.
Most pā tuna were pā tauremu – two fences that funnelled the eels into a hīnaki.
The fences were made of strong stakes (usually mānuka) driven into the river bed, with mānuka brush or bracken fern between the posts. Water could get through, but the eels, coming downstream in large numbers, could not. The two fences were set in a V shape – upstream they were wide apart, but downstream the gap between them narrowed, and a pūrangi (net) guided the eels into a hīnaki.
The number and health of eels in a river were believed to be protected through mauri – talismans, usually stones. These were placed near eel weirs, often at the base of the posts at the downstream end.
Pā auroa – the Whanganui eel weir
A different type of weir was used on the Whanganui River because of the large amount of driftwood in the river. The pā auroa was a single fence, built almost parallel to the current at the top of a rapid. As eels came downstream, the fence guided them into a net attached to the end post and another single post opposite. Pā auroa had to be very strong to withstand floods.
Loss of eel weirs
In the 19th century, European settlers removed pā tuna to make rivers more navigable, leading to conflict with Māori. In the 1880s, there were more than 350 pā tuna and 92 utu piharau (lamprey weirs) in the Whanganui River. Between 1886 and 1888 over 500 tribal members petitioned the government to save their weirs – but by the turn of the century, almost all were gone.