Weirs

Weirs (pa) were made in two forms, the V-shaped with two converging fences and the single fence set obliquely to the flow of the river. The V-shaped weirs (pa tauremu) were constructed in streams with the wide opening facing the current. A narrow opening was left at the apex of the weir and the end posts of each arm were fitted with cross bars to support the hoop of the funnel-shaped net which led to the trap. Weirs forming a double V (pa tararua) were sometimes made.

Single-fenced weirs (pa auroa) were the common form in the Whanganui River. This type was made to avoid the blocking by drift wood and logs which formed the objection to using V-shaped weirs in large rivers in which logs were floated down in the floods. The fences Were constructed on old sites which had been determined experimentally page 234by the old-time experts. A second post was set up at the lower end of the fence with cross bars to provide the support for the set traps. The fences were staked close together to present a barrier against fish passing through. Thus eels coming down on the current slipped along the fence and ended up in the trap. Excellent descriptions of eel weirs, well illustrated, have been given by Downes (27) and Best (21). See Plate XVIII.

Weirs were constructed to intercept freshwater fish on their annual migration to the sea to spawn. For eels and other species of small fish, the movements took place in autumn. The weirs were repaired beforehand and traps were set when the first rains occurred at the end of March or early in April. The arrival of the eels was tested by lifting the rope attached to the trap. When the trap filled, as denoted by the weight, another trap fitted with a leading net was substituted. The catch was emptied into a pit dug on the river bank and so the process of changing traps went on during the run. With the river in flood, expert skill was needed in handling the canoe which made repeated trips between the shore and the weir.

The large weirs were made of solid posts well driven in and buttressed but the smaller weirs in streams for catching other freshwater fish were made with lighter stakes and closed in with leafy manuka tops or bracken fern. Some of the smaller fish which migrated down stream in the autumn to spawn in the river estuaries were the adult form of whitebait (inanga, Galaxias attenuatus), the smelt or tikihemi (Retropinna retropinna), and the panokonoko (Cheimarricthys fosteri). The grayling or upokororo (Prototroctes oxyrhincus) was caught in nets set in a stream with rocks and boulders arranged to form a low weir. A good deal of confusion is caused by the number of Maori names for the same fish due to different tribal names and to different names for various sizes of the same fish.

A clever form of weir termed utu was made to intercept lamprey eels (piharau) when they ascended the rivers in June or July. The eel weirs were of no use because the lampreys were working up against the current. The ingenuity of the Maori solved the problem by erecting a fence at right angles to the river bank. The fence was well stayed and thatched with manuka brush but openings were left through which the water rushed with some force during the freshets when the lampreys worked up stream close to the bank. Scour mats of manuka brush were laid above and below the fence to prevent scouring of the river bottom. Two posts with cross bars were erected a little way down stream below each opening and the hinaki traps with the hooped leading net were held in the same way as in the eel weirs. The ascending lampreys on reaching the weir fence worked along for an opening to continue their onward course. When they came to an opening and attempted to pass through, the rush page 235of water swept them back into the open mouth of the hoop net and so into the trap. The construction of a lamprey weir on the Whanganui River is described in detail by Best (21, p. 160).