title: Abundance, behaviour and habitat requirements of the banded kokopu Galaxias fasciatus Gray (Pisces: Galaxiidae)

authors: McCullough, Cherie

subjects: Fisheries

abstract: The native freshwater banded kokopu (Galaxias fasciatus Gray) is generally regarded as a nocturnal predator of small native forest streams.  Current methods for determining absolute abundances of this species in these streams is usually by the expensive, labour intensive, and invasive method of electric fishing.  Spotlighting at night has previously been used to determine their presence and relative abundance, although the proportion seen (the bias of the method) was unknown.  This bias was quantified by determining the numbers of banded kokopu seen at night in 20 m reaches against population estimates made in the same reaches the following day by removal electric fishing.  This showed that, on average, only around 64% of fish of all sizes were being seen.  Counts made by spotlighting therefore should be multiplied by 1.57 to correct for this bias and to estimate for the actual number of fish present.  Spotlighting was found to be less efficient for smaller fish (approximately <60 mm total length), with only around 42% being observed.  Spotlight counts for smaller fish therefore needed to be multiplied by 2.41 to estimate the actual abundances of fish of this size.  Fish larger than this size, however, were more often seen (0.70) requiring their spotlight counts only to be multiplied by 1.42 to correct for their spotlight estimates.

	Banded kokopu diel activity was studied using time-lapse video recordings with a low-light sensitive camera placed above pools in natural streams.  Two major activity peaks were noted; one from 6:00 a.m. to around 8:00 a.m., the other from around 2:00 p.m. to around 7:30 p.m.  Foraging behaviour, intra- and interspecific behaviours, and mode of swimming were all also noted.

	Nocturnal habitat preferences and suitability functions were derived for all sizes of banded kokopu together, and then for the two aforementioned size classes separately.  The following variables were tested for; mean column water velocity, surface water velocity, column depth, substrate size, and cover type.  Used habitat data was collected at night by a colour filtered spotlight, with a small floating marker being placed at the focal point of the fish.  The particular characteristics of this point were then measured along with available habitat data the following day.  Fish were found to have a very narrow preference for very slow water velocities (around 0.05 m/s), with juveniles preferring slightly faster than adults when considered separately.  Preferred water depths for both sizes were around 0.8 m, and preferred substrate sizes were fine gravels, sand, and silt.  Preferred cover for all sizes was for tree and tree fern roots and undercut banks, as it also was for larger fish when considered separately.  Smaller fish did not use tree fern roots significantly, but instead preferred the cover of cobbles.  This smaller sized fish also made use of tree roots and undercut banks.

	These new banded kokopu habitat preference data were then applied to an IFIM situation in the Waitakere River (West Auckland), where Resource Consent for abstraction of 0.0041 m³/ s (total daily abstraction of 119 m³) was being requested for irrigation of the adjacent Waitakere Golf Course.  The headwaters of this river are situated in the pristine native forest of the Waitakere Ranges.  This river also contains a significant dam (the Waitakere Reservoir) a few kilometres upstream of the proposed site of abstraction which diverts 16, 000 m³ a day to out of stream uses.  This figure represents approximately 80% of water that would otherwise continue downstream and eventually to the ecologically significant freshwater Te Henga Wetland.  Changes in weighted useable area (WUA) as flow decreased as a result of this abstraction were modelled on the DOS program “RHYHABSIM” for fish and invertebrates known to be in this river.  A comparison was also made of this habitat flow method with the North American Tennant method; an historical flow method which determines the effects of flows by set proportions of the mean low flow.  No substantial reduction in WUA was noted for any of the species following abstraction from either a mean low flow (0.0200 m³/s), or a one-in-five-year low flow (0.0134 m³/s).  Endorsement was therefore given for the proposed abstraction to Receive Consent.  Recommendations on the time of day that the abstraction should take place, and other further methods to mitigate the ecological effects of this abstraction are also made.

text: Abundance, behaviour and habitat requirements of the banded kokopu Galaxias fasciatus Gray (Pisces: Galaxiidae) The native freshwater banded kokopu (Galaxias fasciatus Gray) is generally regarded as a nocturnal predator of small native forest streams.  Current methods for determining absolute abundances of this species in these streams is usually by the expensive, labour intensive, and invasive method of electric fishing.  Spotlighting at night has previously been used to determine their presence and relative abundance, although the proportion seen (the bias of the method) was unknown.  This bias was quantified by determining the numbers of banded kokopu seen at night in 20 m reaches against population estimates made in the same reaches the following day by removal electric fishing.  This showed that, on average, only around 64% of fish of all sizes were being seen.  Counts made by spotlighting therefore should be multiplied by 1.57 to correct for this bias and to estimate for the actual number of fish present.  Spotlighting was found to be less efficient for smaller fish (approximately <60 mm total length), with only around 42% being observed.  Spotlight counts for smaller fish therefore needed to be multiplied by 2.41 to estimate the actual abundances of fish of this size.  Fish larger than this size, however, were more often seen (0.70) requiring their spotlight counts only to be multiplied by 1.42 to correct for their spotlight estimates.

	Banded kokopu diel activity was studied using time-lapse video recordings with a low-light sensitive camera placed above pools in natural streams.  Two major activity peaks were noted; one from 6:00 a.m. to around 8:00 a.m., the other from around 2:00 p.m. to around 7:30 p.m.  Foraging behaviour, intra- and interspecific behaviours, and mode of swimming were all also noted.

	Nocturnal habitat preferences and suitability functions were derived for all sizes of banded kokopu together, and then for the two aforementioned size classes separately.  The following variables were tested for; mean column water velocity, surface water velocity, column depth, substrate size, and cover type.  Used habitat data was collected at night by a colour filtered spotlight, with a small floating marker being placed at the focal point of the fish.  The particular characteristics of this point were then measured along with available habitat data the following day.  Fish were found to have a very narrow preference for very slow water velocities (around 0.05 m/s), with juveniles preferring slightly faster than adults when considered separately.  Preferred water depths for both sizes were around 0.8 m, and preferred substrate sizes were fine gravels, sand, and silt.  Preferred cover for all sizes was for tree and tree fern roots and undercut banks, as it also was for larger fish when considered separately.  Smaller fish did not use tree fern roots significantly, but instead preferred the cover of cobbles.  This smaller sized fish also made use of tree roots and undercut banks.

	These new banded kokopu habitat preference data were then applied to an IFIM situation in the Waitakere River (West Auckland), where Resource Consent for abstraction of 0.0041 m³/ s (total daily abstraction of 119 m³) was being requested for irrigation of the adjacent Waitakere Golf Course.  The headwaters of this river are situated in the pristine native forest of the Waitakere Ranges.  This river also contains a significant dam (the Waitakere Reservoir) a few kilometres upstream of the proposed site of abstraction which diverts 16, 000 m³ a day to out of stream uses.  This figure represents approximately 80% of water that would otherwise continue downstream and eventually to the ecologically significant freshwater Te Henga Wetland.  Changes in weighted useable area (WUA) as flow decreased as a result of this abstraction were modelled on the DOS program “RHYHABSIM” for fish and invertebrates known to be in this river.  A comparison was also made of this habitat flow method with the North American Tennant method; an historical flow method which determines the effects of flows by set proportions of the mean low flow.  No substantial reduction in WUA was noted for any of the species following abstraction from either a mean low flow (0.0200 m³/s), or a one-in-five-year low flow (0.0134 m³/s).  Endorsement was therefore given for the proposed abstraction to Receive Consent.  Recommendations on the time of day that the abstraction should take place, and other further methods to mitigate the ecological effects of this abstraction are also made.

year: 1998

title: The freebie problem: A pervasive flaw in how we work out what has value

authors: Weijers, Dan M.

abstract: Nozick’s Experience Machine and Kagan’s Deceived Businessman thought experiments have both been widely used to discredit classical prudential hedonism. The common usage of both thought experiments requires a comparison of two lives in order to show that more than how our experiences feel to us on the inside matters for wellbeing. I identify a structural difference in the way the comparisons work, labelling one method the ‘freebie structure’. I then argue that all thought experiments designed to work out what we value that have the ‘freebie structure’ also have the ‘freebie problem’, which makes them unfit for the purpose of working out what we value. In addition to identifying a serious internal problem with the ‘freebie structure’, I also point out that general acceptance of the ‘freebie structure’ as fit-for-purpose would effectively result in pluralism for all issues of value. It is surprising and alarming, then, that the ‘freebie structure’ is one of our main tools for working out what we value, visible and even prominent in many important philosophical debates.

text: The freebie problem: A pervasive flaw in how we work out what has value Nozick’s Experience Machine and Kagan’s Deceived Businessman thought experiments have both been widely used to discredit classical prudential hedonism. The common usage of both thought experiments requires a comparison of two lives in order to show that more than how our experiences feel to us on the inside matters for wellbeing. I identify a structural difference in the way the comparisons work, labelling one method the ‘freebie structure’. I then argue that all thought experiments designed to work out what we value that have the ‘freebie structure’ also have the ‘freebie problem’, which makes them unfit for the purpose of working out what we value. In addition to identifying a serious internal problem with the ‘freebie structure’, I also point out that general acceptance of the ‘freebie structure’ as fit-for-purpose would effectively result in pluralism for all issues of value. It is surprising and alarming, then, that the ‘freebie structure’ is one of our main tools for working out what we value, visible and even prominent in many important philosophical debates.

year: 2018

title: Outcomes in different ethnic groups of New Zealand patients with screen-detected vs. non-screen-detected breast cancer.

authors: Lawrenson, Ross

subjects: Breast screening

abstract: OBJECTIVE: To compare characteristics and survival of New Zealand European, Māori, and Pacific women with screen-detected vs. non-screen-detected breast cancer. 
METHODS: Women aged 45-69 diagnosed with invasive breast cancer between January 2005 and May 2013 were identified from the Waikato and Auckland Breast Cancer Registries. Patient demographics and tumour characteristics were described by detection mode and ethnicity. Kaplan-Meier method was used to estimate the five-year breast cancer-specific survival of women with stage I-III breast cancer by ethnicity and detection mode. 
RESULTS: Women with screen-detected cancers were older, had smaller tumours, fewer stage IV (0.8% vs. 7.6%), fewer high grade (16.8% vs. 39.0%), and fewer lymph node positive diseases (26.3% vs. 51.5%) than women with non-screen-detected cancers. There were more Luminal A (70.0% vs. 54.0%), fewer human epidermal growth factor receptor 2 positive non-Luminal (4.4% vs. 8.8%), and fewer triple negative cases (7.0% vs. 13.8%) in screen-detected than non-screen-detected cancers. If not screen detected, 22.7% of breast cancers in Pacific women were stage IV compared with 2.4% if screen detected. If not screen detected, the five-year breast cancer-specific survival was 91.1% for New Zealand European women, 84.2% for Māori women, and 80.2% for Pacific women (p-value <0.001). For screen-detected breast cancer, survival between different ethnic groups was similar.
CONCLUSIONS: Breast cancers detected through screening are diagnosed at an earlier stage and have a greater proportion of subtypes, with better outcome. Variations in survival for Māori and Pacific women are only found in women with non-screen-detected breast cancer.

text: Outcomes in different ethnic groups of New Zealand patients with screen-detected vs. non-screen-detected breast cancer. OBJECTIVE: To compare characteristics and survival of New Zealand European, Māori, and Pacific women with screen-detected vs. non-screen-detected breast cancer. 
METHODS: Women aged 45-69 diagnosed with invasive breast cancer between January 2005 and May 2013 were identified from the Waikato and Auckland Breast Cancer Registries. Patient demographics and tumour characteristics were described by detection mode and ethnicity. Kaplan-Meier method was used to estimate the five-year breast cancer-specific survival of women with stage I-III breast cancer by ethnicity and detection mode. 
RESULTS: Women with screen-detected cancers were older, had smaller tumours, fewer stage IV (0.8% vs. 7.6%), fewer high grade (16.8% vs. 39.0%), and fewer lymph node positive diseases (26.3% vs. 51.5%) than women with non-screen-detected cancers. There were more Luminal A (70.0% vs. 54.0%), fewer human epidermal growth factor receptor 2 positive non-Luminal (4.4% vs. 8.8%), and fewer triple negative cases (7.0% vs. 13.8%) in screen-detected than non-screen-detected cancers. If not screen detected, 22.7% of breast cancers in Pacific women were stage IV compared with 2.4% if screen detected. If not screen detected, the five-year breast cancer-specific survival was 91.1% for New Zealand European women, 84.2% for Māori women, and 80.2% for Pacific women (p-value <0.001). For screen-detected breast cancer, survival between different ethnic groups was similar.
CONCLUSIONS: Breast cancers detected through screening are diagnosed at an earlier stage and have a greater proportion of subtypes, with better outcome. Variations in survival for Māori and Pacific women are only found in women with non-screen-detected breast cancer.

year: 2019