Cheimarrichthys fosteri Haast, 1874, Otira River, New Zealand. Placed in its own
or considered a member of the Pinguipedidae. The latter placement is based on general similarity; the only cladistic studies provide no evidence of a close relationship of Cheimarrichthys and pinguipedids.
OTHER COMMON NAMES
A broad, somewhat flattened, wedge-shaped head; subterminal mouth; and robust, scaled body. The dorsal fin has three to five short spines and 18–21 segmented rays; the anal fin has one or two spines and 14–16 segmented rays. The pectoral and pelvic fins are large, with about 50 lateral line scales. Grows to 8 in (20 cm).
Endemic to New Zealand.
Gravel-bottomed rivers in swift riffles from sea level to 2,300 ft (700 m) in elevation and almost 180 mi (300 km) from the sea.
Females occupy areas upstream and males the lower reaches. Diadromous, with juveniles returning from the sea in spring and summer, when they have grown to 0.6–0.8 in (16–20 mm) and are already fully benthic.
FEEDING ECOLOGY AND DIET
Eats slow-moving benthic aquatic insects, especially midges, beetles, and caddis flies, which it probably grazes from cobble/ boulder substrates. Thought to move at night from riffles to pools to feed.
It is suggested that females migrate downstream for spawning in summer/autumn, although spawning sites and
are unknown. Estimated to lay up to 30,000 small eggs, 0.02 in (0.6 mm) in diameter, that probably sink into the substrate, with larvae developing at sea.
Not threatened, though upstream migration is disrupted easily by man-made structures such as dams.
SIGNIFICANCE TO HUMANS
Of traditional importance to the Maori, but subject to no present utilization.
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