title: Age and growth of longfinned eels (Anguilla dieffenbachii) in pastoral and forested streams in the Waikato River basin, and in two hydro-electric lakes in the North Island, New Zealand

authors: Chisnall, Benjamin L.

subjects: biology

abstract: Growth rates of New Zealand endemic longfinned eels (Anguilla dieffenbachii) from streams in pasture and indigenous forest, and from two hydroelectric lakes (Lakes Karapiro and Matahina), were estimated by otolith examination. Habitat-specific growth was further investigated with measurement of widths of annual bands in otoliths. Longfinned eels 170-1095 mm in length ranged between 4 and 60 years old (N=252). Eels in pastoral streams grew faster (mean annual length increment ±95% CL = 24 ± 3 mm to 36 ± 7 mm) than eels in streams in indigenous forest (annual length increment 12 ± 2 mm to 15 ± 3 mm). Eels from the hydro-electric lakes had growth rates (annual length increments 19 ± 4 and 19 + 7 mm) similar to eels from pastoral streams. Otoliths of most eels showed annual band widths that indicated growth in several different habitats, corresponding to growth during upstream migration, and limited movement among adult habitats. Estimated age at marketable size (220 g) ranged between 7 and 26 years. The particularly slow growth of longfinned eels in streams in indigenous forest has considerable implications for management. The fast growth rates of eels in hydro-electric lakes provides evidence for the potential of increased eel production by stocking. The probable selective production of female eels in these lakes may be nationally important to allow enhancement of breeding stocks.

text: Age and growth of longfinned eels (Anguilla dieffenbachii) in pastoral and forested streams in the Waikato River basin, and in two hydro-electric lakes in the North Island, New Zealand Growth rates of New Zealand endemic longfinned eels (Anguilla dieffenbachii) from streams in pasture and indigenous forest, and from two hydroelectric lakes (Lakes Karapiro and Matahina), were estimated by otolith examination. Habitat-specific growth was further investigated with measurement of widths of annual bands in otoliths. Longfinned eels 170-1095 mm in length ranged between 4 and 60 years old (N=252). Eels in pastoral streams grew faster (mean annual length increment ±95% CL = 24 ± 3 mm to 36 ± 7 mm) than eels in streams in indigenous forest (annual length increment 12 ± 2 mm to 15 ± 3 mm). Eels from the hydro-electric lakes had growth rates (annual length increments 19 ± 4 and 19 + 7 mm) similar to eels from pastoral streams. Otoliths of most eels showed annual band widths that indicated growth in several different habitats, corresponding to growth during upstream migration, and limited movement among adult habitats. Estimated age at marketable size (220 g) ranged between 7 and 26 years. The particularly slow growth of longfinned eels in streams in indigenous forest has considerable implications for management. The fast growth rates of eels in hydro-electric lakes provides evidence for the potential of increased eel production by stocking. The probable selective production of female eels in these lakes may be nationally important to allow enhancement of breeding stocks.

year: 1993

title: A Study of the length weight relationships and diets of non-indigenous Poecillids in New Zealand geothermal Streams

authors: Houlihan, David

abstract: Poecillids are highly specialised and well adapted to surviving in highly undesirable conditions. Because of this they have been able to establish populations in many areas where have been released. There are two species of poecillids in New Zealand that have established populations in thermal waters. Sailfin mollies (Poecilia latapinna) are found the South Taupo wetlands near Tokaanu, and the Guppies (Poecilia reticulata) are found at multiple sites in and near Reporoa. These fish were known to have been present in New Zealand since at least the 1930s. However, there has been very little study carried out on their ecology in New Zealand. In order to fill this knowledge gap, a study was carried out to assess the approximate population numbers and the health of each of these species. As well as this it was unknown what exactly these species were feeding on in the thermal waters; therefore a gut analysis was carried out to find out which species of invertebrates if any are part of the diets. It was found that both species have very healthy populations in New Zealand thermal waters; as well as this their diets vary considerably between both species. The sex ratios for both species in New Zealand are quite different from those found in other feral populations. The current populations are found to be of reasonable size especially the Sailfin Mollies; which shows just how well adapted these species have become to the New Zealand conditions. Because of the apparent lack of knowledge of these species numbers and feeding habits in New Zealand and the well-known ability of these species to colonise new habitats; it is important to understand the current population health to allow for any potential management programs in the future.

text: A Study of the length weight relationships and diets of non-indigenous Poecillids in New Zealand geothermal Streams Poecillids are highly specialised and well adapted to surviving in highly undesirable conditions. Because of this they have been able to establish populations in many areas where have been released. There are two species of poecillids in New Zealand that have established populations in thermal waters. Sailfin mollies (Poecilia latapinna) are found the South Taupo wetlands near Tokaanu, and the Guppies (Poecilia reticulata) are found at multiple sites in and near Reporoa. These fish were known to have been present in New Zealand since at least the 1930s. However, there has been very little study carried out on their ecology in New Zealand. In order to fill this knowledge gap, a study was carried out to assess the approximate population numbers and the health of each of these species. As well as this it was unknown what exactly these species were feeding on in the thermal waters; therefore a gut analysis was carried out to find out which species of invertebrates if any are part of the diets. It was found that both species have very healthy populations in New Zealand thermal waters; as well as this their diets vary considerably between both species. The sex ratios for both species in New Zealand are quite different from those found in other feral populations. The current populations are found to be of reasonable size especially the Sailfin Mollies; which shows just how well adapted these species have become to the New Zealand conditions. Because of the apparent lack of knowledge of these species numbers and feeding habits in New Zealand and the well-known ability of these species to colonise new habitats; it is important to understand the current population health to allow for any potential management programs in the future.

year: 2016

title: Participant responses to a tertiary-level Māori language immersion programme: Reporting on a questionnaire-based survey

authors: Nock, Sophie

subjects: Hamilton (N.Z.)

abstract: The article reports about a research project which was aimed at collecting and analyzing data related to the views of the students about a degree programme related to the Māori language in University of Waikato in 2008. As mentioned, a questionnaire was conducted to obtain the responses of the students. But the study revealed that success inhibiting factors were there which affected learning ability of learners, and students had little language proficiency.

text: Participant responses to a tertiary-level Māori language immersion programme: Reporting on a questionnaire-based survey The article reports about a research project which was aimed at collecting and analyzing data related to the views of the students about a degree programme related to the Māori language in University of Waikato in 2008. As mentioned, a questionnaire was conducted to obtain the responses of the students. But the study revealed that success inhibiting factors were there which affected learning ability of learners, and students had little language proficiency.

year: 2010