Kokopu

Abstract: The pH values preferred and avoided by adult stages of inanga (Galaxias maculatus), common bully (Gobiomorphus cotidianus), common smelt (Retropinna retropinna), and redfinned bully (G. huttoni), were determined in a gradient tank (pH ranges of 3.2–11.2). Juvenile stages of inanga, common bully, shortjawed kokopu (Galaxias postvectus), koaro (G. brevipinnis), banded kokopu (G. fasciatus), shortfinned (Anguilla australis) and longfinned (A. dieffenbachii) elvers and glass eels, as well as freshwater shrimp (Paratya curvirostris) were also tested. Most species were found to have pH preferences and all except inanga avoided pH values of above c. 9.5. Adult fish showed stronger preferences than juveniles. An avoidance of pH values below 6.5 was apparent in most species except shortfinned elvers, koaro, and banded kokopu. Results indicate that the range of pH encountered in lowland streams are unlikely to have a major impact on the distribution of most New Zealand native freshwater fish.

Abstract: The distribution and abundance of native fish were investigated in 16 tributary streams of the Waikato River near Hamilton, in the region of Pirongia Forest Park and the Hakarimata Range , and two nearby coastal streams. We found a total of twelve species of native fish, and two introduced species (rainbow and brown trout), at study sites in upland native forest and lowland pastoral areas. At most sites the fish community was relatively depauperate, both in species diversity and in abundance. Only longfinned eel was found at the majority (92%) of sites, while other species were recorded from a minimum of 2% (inanga) to a maximum of 30% (common bully) of sites. Over half of all native fish species were recorded at fewer than 10% of all sites; species in the family Galaxiidae were recorded from only 7% of sites. Large galaxiid species (banded, giant and short-jawed kokopu and koaro) were very sparsely distributed and low in abundance at most sites, and were generally absent from lowland pastoral si...

Abstract: The shortjawed kokopu is found almost exclusively in forested catchments throughout New Zealand. Forest composition appears to be important: the species is found particularly in podocarp/hard‐wood forests, quite often in podocarp/hardwood/ beech associations, but only very rarely in pure beech forest. Sites where shortjawed kokopu are more abundant are always in podocarp/hardwood forest streams. Analysis of distribution in two representative West Coast river systems, the Buller and Grey, shows that there are numerous sampled streams in beech forest catchments within easy reach of shortjawed kokopu migrating upstream from the sea. The shortjawed kokopu is widely present on the West Coast within the “beech gap”, an area between 42°30’ and 43°30'S, from where it is believed that all vegetation was extirpated during Pleistocene glaciations. This area is now forested by podocarp/ hardwood associations because beech forest (Nothofagus spp.) has, as yet, been unable to reinvade. Reasons for this prefere...

Abstract: Selections from unpublished notes by Charles Douglas (1840–1916) illustrate late nineteenthcentury knowedge of and beliefs about the New Zealand freshwater fish fauna. Species mentioned are the lamprey (Geotria australis), short- and longfinned eels (Anguilla australis and A. dieffenbachii), kokopu (Galaxias argenteus and G. fasciatus), koaro (G. brevipinnis), brown mudfish (Neochanna apoda), inanga (G. maculatus), grayling (Protolroctes oxyrhynchus), yellow-eyed mullet (Aldrichetta forsteri), black flounder (Rhombosolea retiaria), and brown trout (Salmo trutta).