Bj. Hicks et Hmc. Mccaughan, LAND-USE, ASSOCIATED EEL PRODUCTION, AND ABUNDANCE OF FISH AND CRAYFISH IN STREAMS IN WAIKATO, NEW-ZEALAND, New Zealand Journal of Marine and Freshwater Research, 31(5), 1997, pp. 635-650
The density and biomass of fish and crayfish, and the production of ee
ls, was compared among streams in native forest, exotic forest, and pa
sture. Populations were estimated by multiple-pass electroshocking at
II sites in hill-country streams in the Waikato region, North Island.
Three sites were in native forest, four in exotic forest, and four in
pasture. Length of stream sampled at each site was 46-94 m (41-246 m(2
) in area), and catchment areas up stream of the sites ranged from 0.4
4 to 2.01 km(2). A total of 487 fish were caught. The species were lon
gfinned and shortfinned eels, banded kokopu, Cran's and redfinned bull
ies, and common smelt. Eels were the most abundant fish in all three l
and-use types, and shortfinned eels were more abundant at pastoral sit
es (mean density 1.11 fish m(-2)) than longfinned eels (mean density 0
.129 fish m(-2)). Banded kokopu were present only at forested sites. M
ean fish densities were greater at pastoral sites (1.55 fish m(-2)) th
an under either native forest (0.130 fish m(-2)) or exotic forest (0.2
29 fish m(-2)). Mean fish biomass was also greater at pastoral sites (
89.7 g m(-2)) than under native forest (12.8 g m(-2)) or exotic forest
(19.3 g m(-2)). Longfinned eels made a greater contribution to the fis
h biomass at all sites than did shortfinned eels. Densities of crayfis
h were high (0.46-5.40 crayfish m(-2)), but were not significantly dif
ferent between land-use types. Crayfish biomass ranged from 1.79 to 11
.2 g m(-2) Total eel production was greater at pastoral sites (mean 17
.9 g m(-2) year(-1)) than at forest sites (mean 2.39 g m(-2) year(-1))
.