title: Assessment of fish populations in Lake Horowhenua, Levin

authors: Tempero, Grant Wayne

subjects: Lake Horowhenua

abstract: Lake Horowhenua (Waipunahau) is of substantial historical, cultural and recreational value to the people of the Horowhenua region. However, water quality and biodiversity within the lake has been in decline for a number of years. As part of lake restoration efforts by Horizons Regional Council and the Lake Horowhenua Trustees, a survey of fish species in Lake Horowhenua was conducted by the University of Waikato using boat electrofishing and fyke netting. A lake restoration plan had previously identified invasive fish species such as koi carp (Cyprinus carpio) and European perch (Perca fluviatilis) as being potential barriers to rehabilitation of the lake. The purpose of this survey was to determine the abundance and diversity of fish species within the lake and to ascertain if pest fish species were present at biomasses high enough to be negatively impacting on lake ecology. Recommendations would then be made as to the potential methods and necessity for pest fish removal.

text: Assessment of fish populations in Lake Horowhenua, Levin Lake Horowhenua (Waipunahau) is of substantial historical, cultural and recreational value to the people of the Horowhenua region. However, water quality and biodiversity within the lake has been in decline for a number of years. As part of lake restoration efforts by Horizons Regional Council and the Lake Horowhenua Trustees, a survey of fish species in Lake Horowhenua was conducted by the University of Waikato using boat electrofishing and fyke netting. A lake restoration plan had previously identified invasive fish species such as koi carp (Cyprinus carpio) and European perch (Perca fluviatilis) as being potential barriers to rehabilitation of the lake. The purpose of this survey was to determine the abundance and diversity of fish species within the lake and to ascertain if pest fish species were present at biomasses high enough to be negatively impacting on lake ecology. Recommendations would then be made as to the potential methods and necessity for pest fish removal.

year: 2013

title: Pātangaroa: Co-developing management strategies for a starfish outbreak in Ōhiwa Harbour

authors: Ranapia, Megan

subjects: marine management

abstract: The management of marine environments often prioritises scientific information to address complex marine social-ecological issues. However, there is a wealth of learning to be gained from Indigenous people who have generated place-based intergenerational understandings and cultural ethics and practices. Consequently, Indigenous knowledge alongside science can offer better insights, holistic understanding, sustainable management strategies and greater sources of evidence. This research is located in Aotearoa New Zealand and engages in mātauranga Māori (Māori knowledge) alongside marine ecology as an appropriate method for contemporary marine research and management. The thesis study focused on Ōhiwa Harbour, aiming to co-develop a starfish management action plan (SMAP) with local iwi (tribe) Ngāti Awa and other affiliated iwi, district councils and regional council to address the overabundant starfish (species: Coscinasterias muricata and Patiriella regularis). By engaging in transdisciplinary research and collaborative decision-making, this study sought to bridge the gap between Indigenous knowledge and mainstream science, offering lessons for inclusive marine management practices.

To achieve this, I developed and prescribed a co-developed framework actively promoting a mixed-methods approach, inclusive of kaupapa Māori research methodologies, tikanga, participatory design, applied mātauranga ā iwi, quantitative marine scientific field methods and experimental study design. Through the collaborative process, I identified areas of appropriate research aims and methods. This included co-developing a novel starfish trapping methodology sensitive to local ecology and cultural values and an experimental starfish removal study to assist decision-makers in implementing an efficient and effective starfish removal regime as an approach to management.

Results from the field studies showed the efficacy of starfish traps is dependent on environmental conditions, physical characteristics and soaking time (the length of time the trap is left in the water). A soaking time of 48 h maintained the highest starfish catch per unit effort (CPUE) while minimising time to re-bait and reset traps. Observations also indicated an open trap design had less bycatch than a semi-enclosed box trap and could withstand the tidal currents for a longer period. The findings found that bait type did not impact on CPUE. In the starfish removal study, the combined effort of diver removals and trapping produced higher daily catch rates than the single treatments (i.e., diver removals only or trapping only), therefore was themost efficient removal method. The empirical information gathered from the field studies was then used to inform the SMAP and was accepted unanimously at the highest local/regional co-management level. Furthermore, through the findings I identified future research opportunities that would further close gaps in our knowledge around the best management approaches for a starfish outbreak. These included investigation into the predation impacts of P. regularis on mussel recruitment, identification of alternative restoration sites less susceptible to starfish predation pressures and investigation of potential drivers of the starfish outbreak.

Overall, the acceptance of the SMAP by local iwi/hapū and government authorities underscores the success of the collaborative approach. The collaborative process not only addresses the immediate concerns of starfish infestation but contributed to the broader goal of supporting kaitiakitanga (active guardianship) responsibilities and promoting Indigenous perspectives in marine management. This thesis demonstrates and recommends a new approach to starfish management in coastal marine areas using both marine science and mātauranga Māori understandings, practices and ethics, furthermore, it demonstrates the commitment to the inclusion of multiple knowledge systems and involvement of communities.

text: Pātangaroa: Co-developing management strategies for a starfish outbreak in Ōhiwa Harbour The management of marine environments often prioritises scientific information to address complex marine social-ecological issues. However, there is a wealth of learning to be gained from Indigenous people who have generated place-based intergenerational understandings and cultural ethics and practices. Consequently, Indigenous knowledge alongside science can offer better insights, holistic understanding, sustainable management strategies and greater sources of evidence. This research is located in Aotearoa New Zealand and engages in mātauranga Māori (Māori knowledge) alongside marine ecology as an appropriate method for contemporary marine research and management. The thesis study focused on Ōhiwa Harbour, aiming to co-develop a starfish management action plan (SMAP) with local iwi (tribe) Ngāti Awa and other affiliated iwi, district councils and regional council to address the overabundant starfish (species: Coscinasterias muricata and Patiriella regularis). By engaging in transdisciplinary research and collaborative decision-making, this study sought to bridge the gap between Indigenous knowledge and mainstream science, offering lessons for inclusive marine management practices.

To achieve this, I developed and prescribed a co-developed framework actively promoting a mixed-methods approach, inclusive of kaupapa Māori research methodologies, tikanga, participatory design, applied mātauranga ā iwi, quantitative marine scientific field methods and experimental study design. Through the collaborative process, I identified areas of appropriate research aims and methods. This included co-developing a novel starfish trapping methodology sensitive to local ecology and cultural values and an experimental starfish removal study to assist decision-makers in implementing an efficient and effective starfish removal regime as an approach to management.

Results from the field studies showed the efficacy of starfish traps is dependent on environmental conditions, physical characteristics and soaking time (the length of time the trap is left in the water). A soaking time of 48 h maintained the highest starfish catch per unit effort (CPUE) while minimising time to re-bait and reset traps. Observations also indicated an open trap design had less bycatch than a semi-enclosed box trap and could withstand the tidal currents for a longer period. The findings found that bait type did not impact on CPUE. In the starfish removal study, the combined effort of diver removals and trapping produced higher daily catch rates than the single treatments (i.e., diver removals only or trapping only), therefore was themost efficient removal method. The empirical information gathered from the field studies was then used to inform the SMAP and was accepted unanimously at the highest local/regional co-management level. Furthermore, through the findings I identified future research opportunities that would further close gaps in our knowledge around the best management approaches for a starfish outbreak. These included investigation into the predation impacts of P. regularis on mussel recruitment, identification of alternative restoration sites less susceptible to starfish predation pressures and investigation of potential drivers of the starfish outbreak.

Overall, the acceptance of the SMAP by local iwi/hapū and government authorities underscores the success of the collaborative approach. The collaborative process not only addresses the immediate concerns of starfish infestation but contributed to the broader goal of supporting kaitiakitanga (active guardianship) responsibilities and promoting Indigenous perspectives in marine management. This thesis demonstrates and recommends a new approach to starfish management in coastal marine areas using both marine science and mātauranga Māori understandings, practices and ethics, furthermore, it demonstrates the commitment to the inclusion of multiple knowledge systems and involvement of communities.

year: 2025-05

title: Dibbling Machine for ArborGen

authors: Duke, Mike

abstract: ArborGen’s nursery, located in Tokoroa, supplies approximately 6 million seedlings per year to the forestry industry (figure 1). The vast majority of seedlings are Pine Radiata but they also supply Plug Plus and Douglas fir. In peak season, they plant up to 120,000 seedlings per day that each require a straight vertical hole of certain depth and spacing, (depending on seedling type). For example the most common seedling, Radiata pine, requires holes of approximately 10mm diameter x 40mm deep (figure 2). The process of making the holes is called dibbling. Dibbling has become a major problem that has resulted in an estimated 400,000 rejections per year. An investigation of the dibbling process identified the following problems: • Existing human dibbling methods too slow and unreliable • Machine methods produce low quality holes that lead to mis-planted seedlings • Lack of flexibility of existing, methods with regard to hole size and spacing • Current methods compact the soil hindering root growth so hole drilling is preferred • Currently, dibbling must be done on the day of planting due to the deterioration of the bed surface

text: Dibbling Machine for ArborGen ArborGen’s nursery, located in Tokoroa, supplies approximately 6 million seedlings per year to the forestry industry (figure 1). The vast majority of seedlings are Pine Radiata but they also supply Plug Plus and Douglas fir. In peak season, they plant up to 120,000 seedlings per day that each require a straight vertical hole of certain depth and spacing, (depending on seedling type). For example the most common seedling, Radiata pine, requires holes of approximately 10mm diameter x 40mm deep (figure 2). The process of making the holes is called dibbling. Dibbling has become a major problem that has resulted in an estimated 400,000 rejections per year. An investigation of the dibbling process identified the following problems: • Existing human dibbling methods too slow and unreliable • Machine methods produce low quality holes that lead to mis-planted seedlings • Lack of flexibility of existing, methods with regard to hole size and spacing • Current methods compact the soil hindering root growth so hole drilling is preferred • Currently, dibbling must be done on the day of planting due to the deterioration of the bed surface

year: 2014-01-18