Summary
Interim report 1999
A total of 96 shortjawed kokopu were found in 12 streams in the Abel Tasman National Park and in Golden Bay. This is a surprisingly high number for a category 'A' threatened species given the low numbers found at sites on the New Zealand Freshwater Fish Database. A third of all streams surveyed contained shortjawed kokopu compared to 2% of streams in the NZFFD. A higher proportion of streams with shortjawed kokopu were found inside the Abel Tasman National Park than in Golden Bay supporting findings that shortjawed kokopu prefer relatively unmodified streams with good riparian cover. This is a significant find and it highlights the Abel Tasman National Park as a stronghold for the species.
Spotlighting and electric fishing survey methods were compared. Spotlighting was found to be a more effective survey technique than electric fishing in the Abel Tasman area. The number of shortjawed kokopu caught at sites by spotlight technique (45) was considerably higher than the total number caught by electric fishing (1). This could be due to the presence of large granite boulders in the Abel Tasman streams which shortjawed kokopu can hide under, making it difficult to reach them with the electric field.
Shortjawed kokopu were found in a wide size range of rivers including some quite large rivers, contrary to previous findings that suggest they prefer small streams.
No juvenile shortjawed kokopu were captured during the survey. It is possible that juveniles were present amongst schools of juveniles identified as banded kokopu and koaro. A reasonably healthy size range of shortjawed kokopu was found inside the Abel Tasman. Outside the park subadults and large fish were thinly represented possibly indicating poor recruitment, a shorter life span or slower growth rate.
In the following 2 years of the survey more time should be spent trying to capture juvenile shortjawed kokopu. Other management recommendations are also discussed.
Interim report 2000
A total of 176 short-jawed kokopu were either caught or observed in surveyed streams, with 108 (18 sites) within conservation estate. Short-jawed kokopu were found in 27 of the 48 streams surveyed, with 20 of these streams containing previously undocumented populations. Clusters of populations occurred in four main areas, notably Croisilles Harbour, Tennyson Inlet, Endeavor Inlet and Nydia Bay streams. Seven new populations of giant kokopu were discovered during short-jawed kokopu survey, and banded kokopu occurred in nearly all streams surveyed.
Short-jawed kokopu are able to inhabit streams with a certain amount of land modification, provided the stream originates from mature or regenerating native forest and remains relatively healthy. Populations disappeared as landuse impacts increased down catchments.
Low numbers of juvenile and sub adult short-jawed kokopu were widely represented throughout the Marlborough Sounds. Preferred microhabitat of juvenile and sub adults included eddies and small holding areas within riffles and rapids, back waters, and runs/pools associated with adults.
Castor Stream (Croiselles Harbour) shows the importance of intact lowland coastal forest for freshwater fauna. Integrating this area and other core short-jawed kokopu streams into the Department of Conservation RAP process is discussed along with other management recommendations.
Interim report 2001
A total of 329 shortjawed kokopu were either caught or observed in 36 out of 64 streams surveyed through out the Golden Bay and Murchison areas over summer 2001. Of these 36 streams, 32 had previously never had shortjawed kokopu recorded from them. Population distributions occurred predominantly throughout tributaries of the Aorere River and relatively unmodified river systems of the North West Nelson coast such as the Turamawiwi, Anaweka and Kahurangi rivers. Large population distributions were located in some of these waterways, with the largest occurring in the Kaituna River, where 40 individual fish were located within the survey reach. A diverse range of other native fishes including all other New Zealand diadromus galaxiids were documented along with shortjawed kokopu populations. Five new giant kokopu population distributions were also located during the course of the survey.
Shortjawed kokopu appear to be able to occupy a variety of stream habitats within moderately intensive land use, provided native riparian vegetation exists, and stream catchments have some native forest in their headwaters. In areas of high intensity land use, shortjawed kokopu are restricted to above the fringes of agriculture and development, usually within primary and/or secondary forest.
Significant numbers of juvenile and subadult shortjawed kokopu were found throughout the Golden Bay and North West Coast survey area. This contrasts to the previous two years surveys findings and may indicate recruitment success and habitat availability with-in these areas.
Shortjawed kokopu were found in conjunction with moderate numbers of small (40 - 250 mm TL) brown trout occupying similar microhabitat in 22 of the 36 streams.
Rivers draining the Wakakmarama Range with high native fishery values demonstrate that Kahurangi National Park, along with Abel Tasman National Park, provides significant habitat nationally, for threatened migratory galaxiids.
Management recommendations regarding directions for future research and management work on threatened galaxiids, both regionally and nationally, are discussed.
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