title: Habitat use and trophic ecology of bronze whaler sharks (Carcharhinus brachyurus) in New Zealand

authors: Kellett, Melissa Danielle

subjects: Bronze whaler shark (Carcharhinus brachyurus)

abstract: Sharks are among some of the most diverse and abundant top-level predators within marine ecosystems.  Their predatory role in controlling the population size, distribution and behaviour of species within the lower levels of the food web make them an integral component in both coastal and oceanic communities.  However, anthropogenic pressures are causing declines in many shark populations across their range, with the ecological consequences following the removal of top predators from marine communities yet to be fully understood.  Insight into the dynamics of shark ecology is further complicated by the heterogeneity of variables regulating natural communities.  Despite this, research on trophic cascades, and the direct and indirect effects of apex predators on successive levels of the food web has been achieved where top-level predators have been removed from systems. 

As a consequence of the difficulty in researching elusive species such as sharks in the marine environment, an understanding of the biology and ecology of many species remains limited.  However, such information is critical if effective decisions on the management of shark species and the wider marine environment in which they interact, are to be made.  Although considered common, the bronze whaler shark (Carcharhinus brachyurus) remains relatively unstudied.  Found in warm temperate environments, this species is known to utilise coastal habitats during the summer months.  However, little is known about their movements during the winter months when sightings and interactions with fishermen in nearshore waters cease.  Using satellite-linked smart position or temperature transmitting (SPOT5) tags and stable isotope analysis, this research aims to investigate the habitat use and trophic ecology of bronze whaler sharks to establish their role as top-level predators within coastal New Zealand waters.  This research further aims to build on current knowledge to ensure sound management decisions regarding this species, and to understand the possible ecological community effects if these predators are removed from local marine systems.  

Satellite telemetry has revolutionised the way in which scientists track highly mobile vertebrates, and continues to expand our understanding of the behaviour and distribution patterns of shark species across a range of environments and geographic scales.  This study provides the first report of the use of satellite tags on bronze whaler sharks.  Two mature female bronze whaler sharks were tagged with satellite-linked smart position or temperature transmitting (SPOT5) tags at the entrance to the southern Tauranga Harbour, New Zealand.  Sharks were tagged during April, the beginning of the austral autumn, and tracked for up to 157 days until transmissions ceased towards the end of winter in September.  While transmission periods were comparable to those found throughout the literature, transmission rates were low which could be a factor of the surfacing behaviour of this species.  However, location accuracies exceeded those of other studies, providing viable tracks for analysis for both sharks.  Movement and recapture data indicated a high level of residency and site fidelity to habitats within the north-eastern region of the North Island, New Zealand, suggesting bronze whaler sharks play an important top-down predatory role in structuring the food web dynamic in this region.  This also indicated the potential for multiple segregated populations within New Zealand waters.  Furthermore, a behavioural shift was evident with the onset of winter, with both sharks moving from inshore and shelf habitats during autumn, to primarily shelf-edge and oceanic habitats during winter.  This movement coincided with a decline in coastal water temperatures below 15.1°C.  The cessation of transmissions, likely due to biofouling, prevented the identification of a return migration to coastal environments the following summer.  However, the data provided new evidence of the importance of shelf-edge and oceanic habitats to this species.  Further understanding of their seasonal movements and feeding ecology would enhance our understanding of how their predatory influence may change across seasons and in turn, the implications for inshore and offshore prey assemblages.

Stable isotope analysis presents an alternative method to track the movements and ecology of species, providing information of species interactions and trophic dynamics that cannot be determined through satellite tagging alone.  This study examined stable isotope signatures δ13C and δ15N of muscle tissue of bronze whaler sharks in comparison with coastal and offshore teleost, invertebrate and algal species from the Bay of Plenty, New Zealand.  A total of 40 bronze whaler sharks were caught from the Tauranga coastal region, ranging in length from 236–305 cm total length across the dorsal surface with the tail in a flexed position.  Based on previous length at maturity studies, sharks in the data set were considered mature.  Out of the 40 sharks captured, only two were male, supporting sex segregation in this species, and a strong association of females to inshore sites.  Stable isotope analysis did not detect a change in δ13C and δ15N values with increasing length, informing that once bronze whaler sharks reached maturity, they fed off a similar food web and at a similar trophic level.  A Bayesian mixing model was applied to estimate the contributions of potential prey species to the diet of bronze whaler sharks.  The model identified kingfish as the most dominant prey source (mean = 50.7%), followed by piper (mean = 11.5%) which indicated the utilisation primarily of a coastal pelagic food web.  Snapper also showed to be an important component, indicating trophic links also extended to reef and benthic habitats.  The lack of a viable pelagic baseline signature prevented the ability to accurately calculate the trophic position of bronze whaler sharks.  However, an examination of bivariate data from all species collected suggest a trophic position between 4 and 5, which was consistent with trophic position estimates previously calculated for bronze whaler sharks and other shark species of a similar size.

This study adopted a multidisciplinary approach to investigate the movement patterns and trophic ecology of bronze whaler sharks captured from coastal sites within the Bay of Plenty.  The use of stable isotope analysis can be a powerful tool to complement satellite tracking studies.  However, in this case, each technique provided a somewhat contradictory result.  It is evident that the ecology of this species is complex, with a larger, more diverse sample size over greater spatial and temporal scales required to further elucidate the many questions still pending over its habitat use and foraging behaviour.  Such information is crucial if we are to fully understand the ecological role this species plays as a top-level predator within local marine communities, and its implications for the wider management of valuable ecosystems and fisheries within the region.

text: Habitat use and trophic ecology of bronze whaler sharks (Carcharhinus brachyurus) in New Zealand Sharks are among some of the most diverse and abundant top-level predators within marine ecosystems.  Their predatory role in controlling the population size, distribution and behaviour of species within the lower levels of the food web make them an integral component in both coastal and oceanic communities.  However, anthropogenic pressures are causing declines in many shark populations across their range, with the ecological consequences following the removal of top predators from marine communities yet to be fully understood.  Insight into the dynamics of shark ecology is further complicated by the heterogeneity of variables regulating natural communities.  Despite this, research on trophic cascades, and the direct and indirect effects of apex predators on successive levels of the food web has been achieved where top-level predators have been removed from systems. 

As a consequence of the difficulty in researching elusive species such as sharks in the marine environment, an understanding of the biology and ecology of many species remains limited.  However, such information is critical if effective decisions on the management of shark species and the wider marine environment in which they interact, are to be made.  Although considered common, the bronze whaler shark (Carcharhinus brachyurus) remains relatively unstudied.  Found in warm temperate environments, this species is known to utilise coastal habitats during the summer months.  However, little is known about their movements during the winter months when sightings and interactions with fishermen in nearshore waters cease.  Using satellite-linked smart position or temperature transmitting (SPOT5) tags and stable isotope analysis, this research aims to investigate the habitat use and trophic ecology of bronze whaler sharks to establish their role as top-level predators within coastal New Zealand waters.  This research further aims to build on current knowledge to ensure sound management decisions regarding this species, and to understand the possible ecological community effects if these predators are removed from local marine systems.  

Satellite telemetry has revolutionised the way in which scientists track highly mobile vertebrates, and continues to expand our understanding of the behaviour and distribution patterns of shark species across a range of environments and geographic scales.  This study provides the first report of the use of satellite tags on bronze whaler sharks.  Two mature female bronze whaler sharks were tagged with satellite-linked smart position or temperature transmitting (SPOT5) tags at the entrance to the southern Tauranga Harbour, New Zealand.  Sharks were tagged during April, the beginning of the austral autumn, and tracked for up to 157 days until transmissions ceased towards the end of winter in September.  While transmission periods were comparable to those found throughout the literature, transmission rates were low which could be a factor of the surfacing behaviour of this species.  However, location accuracies exceeded those of other studies, providing viable tracks for analysis for both sharks.  Movement and recapture data indicated a high level of residency and site fidelity to habitats within the north-eastern region of the North Island, New Zealand, suggesting bronze whaler sharks play an important top-down predatory role in structuring the food web dynamic in this region.  This also indicated the potential for multiple segregated populations within New Zealand waters.  Furthermore, a behavioural shift was evident with the onset of winter, with both sharks moving from inshore and shelf habitats during autumn, to primarily shelf-edge and oceanic habitats during winter.  This movement coincided with a decline in coastal water temperatures below 15.1°C.  The cessation of transmissions, likely due to biofouling, prevented the identification of a return migration to coastal environments the following summer.  However, the data provided new evidence of the importance of shelf-edge and oceanic habitats to this species.  Further understanding of their seasonal movements and feeding ecology would enhance our understanding of how their predatory influence may change across seasons and in turn, the implications for inshore and offshore prey assemblages.

Stable isotope analysis presents an alternative method to track the movements and ecology of species, providing information of species interactions and trophic dynamics that cannot be determined through satellite tagging alone.  This study examined stable isotope signatures δ13C and δ15N of muscle tissue of bronze whaler sharks in comparison with coastal and offshore teleost, invertebrate and algal species from the Bay of Plenty, New Zealand.  A total of 40 bronze whaler sharks were caught from the Tauranga coastal region, ranging in length from 236–305 cm total length across the dorsal surface with the tail in a flexed position.  Based on previous length at maturity studies, sharks in the data set were considered mature.  Out of the 40 sharks captured, only two were male, supporting sex segregation in this species, and a strong association of females to inshore sites.  Stable isotope analysis did not detect a change in δ13C and δ15N values with increasing length, informing that once bronze whaler sharks reached maturity, they fed off a similar food web and at a similar trophic level.  A Bayesian mixing model was applied to estimate the contributions of potential prey species to the diet of bronze whaler sharks.  The model identified kingfish as the most dominant prey source (mean = 50.7%), followed by piper (mean = 11.5%) which indicated the utilisation primarily of a coastal pelagic food web.  Snapper also showed to be an important component, indicating trophic links also extended to reef and benthic habitats.  The lack of a viable pelagic baseline signature prevented the ability to accurately calculate the trophic position of bronze whaler sharks.  However, an examination of bivariate data from all species collected suggest a trophic position between 4 and 5, which was consistent with trophic position estimates previously calculated for bronze whaler sharks and other shark species of a similar size.

This study adopted a multidisciplinary approach to investigate the movement patterns and trophic ecology of bronze whaler sharks captured from coastal sites within the Bay of Plenty.  The use of stable isotope analysis can be a powerful tool to complement satellite tracking studies.  However, in this case, each technique provided a somewhat contradictory result.  It is evident that the ecology of this species is complex, with a larger, more diverse sample size over greater spatial and temporal scales required to further elucidate the many questions still pending over its habitat use and foraging behaviour.  Such information is crucial if we are to fully understand the ecological role this species plays as a top-level predator within local marine communities, and its implications for the wider management of valuable ecosystems and fisheries within the region.

year: 2021

title: Specialist Classroom Teacher Mentoring and Knowledge Generativity: Exploring trust, support, challenge, risk-taking, and confidence.

authors: Atkins, Stephen Gregory

subjects: Mentoring

abstract: The Specialist Classroom Teacher (SCT) position involves a mentoring function that is an integral part of mentoring and induction programmes for teacher-mentees in secondary and area schools in New Zealand. SCT-mentor and teacher-mentee relationships should be confidential and high trust relationships and should involve professional growth for each teacher-mentee as an increase in capacity.
This small scale qualitative study involves three purposefully selected cases each of which comprises a SCT-mentor working collaboratively with a teacher-mentee. Challenge, for professional growth as generativity of new practice and/or knowledge for the mentee, should be evident within the mentoring relationship.
This study begins by examining documentation on the SCT position and how the position relates to mentoring for generativity. A conceptual model provides a focus for the review of the literature because it identifies some of the key concepts initially considered to be central to mentor-mentee interactions. These concepts include trust, support, risk-taking, and challenge, and to these is added confidence because this concept emerged in the data.
Primary data is collected from two naturally occurring mentoring meetings involving each SCT-mentor and teacher-mentee only. This data is analysed and used to formulate questions for one semi-structured interview involving the researcher and each participant pair for each case. Participant perceptions of the concepts and concept interactions within each relationship are sought from interpretive and phenomenological approaches within the interviews.
Whereas there is a major focus on support as a mentoring function in the literature, this study found that trust is the basis of each mentoring relationship and that trust underpins the generative process. Discussion centres on the relationship between trust and support, and significantly confidence emerged as a concept that leads to risk-taking behaviour. This emergence of confidence necessitated a revision of the conceptual model presented in the conclusion. Some key points in the discussion and conclusion are: appropriate challenge, static and futuristic support, fields of support, reflective dialogue using tools such as parallel conversations , and realisations pertaining to the 'conscious competence learning model'.
This study suggests a shift in focus in the literature from support functions of SCT-mentors to trust building functions because trust-based mentoring relationships are more likely to endure, and are more likely to underpin greater risk-taking behaviours. This study questions the notion that 'deepest trust' through value congruence is the deepest form of trust, suggesting that 'acceptance of different values' represents a 'highest form of trust'.

text: Specialist Classroom Teacher Mentoring and Knowledge Generativity: Exploring trust, support, challenge, risk-taking, and confidence. The Specialist Classroom Teacher (SCT) position involves a mentoring function that is an integral part of mentoring and induction programmes for teacher-mentees in secondary and area schools in New Zealand. SCT-mentor and teacher-mentee relationships should be confidential and high trust relationships and should involve professional growth for each teacher-mentee as an increase in capacity.
This small scale qualitative study involves three purposefully selected cases each of which comprises a SCT-mentor working collaboratively with a teacher-mentee. Challenge, for professional growth as generativity of new practice and/or knowledge for the mentee, should be evident within the mentoring relationship.
This study begins by examining documentation on the SCT position and how the position relates to mentoring for generativity. A conceptual model provides a focus for the review of the literature because it identifies some of the key concepts initially considered to be central to mentor-mentee interactions. These concepts include trust, support, risk-taking, and challenge, and to these is added confidence because this concept emerged in the data.
Primary data is collected from two naturally occurring mentoring meetings involving each SCT-mentor and teacher-mentee only. This data is analysed and used to formulate questions for one semi-structured interview involving the researcher and each participant pair for each case. Participant perceptions of the concepts and concept interactions within each relationship are sought from interpretive and phenomenological approaches within the interviews.
Whereas there is a major focus on support as a mentoring function in the literature, this study found that trust is the basis of each mentoring relationship and that trust underpins the generative process. Discussion centres on the relationship between trust and support, and significantly confidence emerged as a concept that leads to risk-taking behaviour. This emergence of confidence necessitated a revision of the conceptual model presented in the conclusion. Some key points in the discussion and conclusion are: appropriate challenge, static and futuristic support, fields of support, reflective dialogue using tools such as parallel conversations , and realisations pertaining to the 'conscious competence learning model'.
This study suggests a shift in focus in the literature from support functions of SCT-mentors to trust building functions because trust-based mentoring relationships are more likely to endure, and are more likely to underpin greater risk-taking behaviours. This study questions the notion that 'deepest trust' through value congruence is the deepest form of trust, suggesting that 'acceptance of different values' represents a 'highest form of trust'.

year: 2012

title: Exploring the experiences of young Māori mothers

authors: Shepherd, Cindy-Joe Theresa Aroha

subjects: Young Māori mothers

abstract: This thesis explores the lived experiences of three young Māori mothers (aged 16 
years old) in Aotearoa, New Zealand, focusing on their strengths, challenges, and resilience. 
By employing a Kaupapa Māori methodological framework, the research aims to reframe 
narratives about young Māori mothers towards a strengths-based perspective, advocating for 
protection and nurturing Māori whakapapa. Using qualitative methods, the study explores the 
pūrākau (stories) of three young Māori mothers attending a teen parent unit in Waikato. 
The study highlights how, by living within both individualistic and collective realms, 
these young mothers actively challenge stigma, assert their worth, and develop unique 
underlying strengths. The findings, structured around emergent themes from their collective 
experiences, reveal a dichotomy: these young mothers must navigate the individualistic 
pressures and high expectations of motherhood while also drawing strength from collective 
responsibilities upheld within their whānau and supportive community services. Despite 
facing significant societal stigma and systemic barriers, the mothers demonstrate immense 
strength. Their resilience is grounded in whānau connections, proactive self-care, and 
engagement with taiao, wairua, and tino rangatiratanga—processes that also support 
intergenerational healing. 
This research underscores the importance of culturally responsive support systems 
that honour Indigenous knowledge and collective well-being. It offers insights for reorienting 
policy and practice to empower young Māori mothers, recognising their tino rangatiratanga 
and transformative agency by embracing their multifaceted realities.

text: Exploring the experiences of young Māori mothers This thesis explores the lived experiences of three young Māori mothers (aged 16 
years old) in Aotearoa, New Zealand, focusing on their strengths, challenges, and resilience. 
By employing a Kaupapa Māori methodological framework, the research aims to reframe 
narratives about young Māori mothers towards a strengths-based perspective, advocating for 
protection and nurturing Māori whakapapa. Using qualitative methods, the study explores the 
pūrākau (stories) of three young Māori mothers attending a teen parent unit in Waikato. 
The study highlights how, by living within both individualistic and collective realms, 
these young mothers actively challenge stigma, assert their worth, and develop unique 
underlying strengths. The findings, structured around emergent themes from their collective 
experiences, reveal a dichotomy: these young mothers must navigate the individualistic 
pressures and high expectations of motherhood while also drawing strength from collective 
responsibilities upheld within their whānau and supportive community services. Despite 
facing significant societal stigma and systemic barriers, the mothers demonstrate immense 
strength. Their resilience is grounded in whānau connections, proactive self-care, and 
engagement with taiao, wairua, and tino rangatiratanga—processes that also support 
intergenerational healing. 
This research underscores the importance of culturally responsive support systems 
that honour Indigenous knowledge and collective well-being. It offers insights for reorienting 
policy and practice to empower young Māori mothers, recognising their tino rangatiratanga 
and transformative agency by embracing their multifaceted realities.

year: 2024-06-23