Stock structure of Patagonian toothfish Dissostichus eleginoides (Smitt 1898, family Nototheniidae) in the Southwest Atlantic
- Authors: Lee, Brendon
- Date: 2022-10-14
- Subjects: Otoliths , Patagonian toothfish Geographical distribution , Fish tagging , Biogeography , Microstructure , Microchemistry
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/365599 , vital:65763 , DOI https://doi.org/10.21504/10962/365599
- Description: The identification of discrete self-sustaining productive units in marine populations is essential for achieving sustainable fisheries objectives. Marine fish populations frequently exhibit dynamic characteristics across their life-histories, displaying variability in spatial structure and mixing patterns, both within and among populations. The incoherent application of management boundaries on biological populations can bias stock assessment results and have important implications on sustainable fisheries management. Patagonian toothfish (Dissostichus eleginoides) is a long-lived, slow-growing, late-maturing, deep-sea, benthopelagic species. It forms the basis of important and highly lucrative industrial and artisanal fisheries across its distribution. Patagonian toothfish have complex life-histories characterised by high dispersal potential during the egg and larval phase, a wide depth range because of their ontogenetic migratory behaviour, and large adult size that is capable of undertaking long-distance active movements (>200 km). These characteristics provide opportunities for high levels of connectivity, and as such, the stock structure is not well understood. We applied an integrated, multidisciplinary approach to provide an improved understanding of the complex stock structure dynamics for Patagonian toothfish on the Patagonian Shelf, specifically in relation to the shelf, slope, and deep-sea plains around the Falkland Islands. Research results were focused on aspects pertaining to (1) geographic variation in phenotypic characters (otolith shape); (2) a description of the spatial-temporal distribution patterns; (3) the active movements of deep-sea adults (tag-recapture study); and (4) the identification of early life-history dispersal through otolith microstructure and microchemical chronologies. Results from the study indicate high regional connectivity during the early life-history stages derived from at least two spawning contingents into spatially discrete nursery areas (cohort groups) on the Falklands Shelf. Fish followed distinct ontogenetic pathways into deeper waters adjacent to the areas wherein juvenile settlement into a demersal habitat occurred. There is little to no evidence of mixing among cohort groups during their ontogenetic migration into deep-sea adult habitats, reflecting a mixed population based on oceanographically defined egg and larval dispersal. The majority of the adult component of the population continue to display high site fidelity. However, between 9 and 25% of the population, consisting predominantly of larger reproductively capable adults undertake long-distance dispersal behaviour, identified as home-range relocations from the adult deep-sea habitats towards three of the known southern spawning grounds in the region. Results are suggestive of a requirement for improved collaborative efforts for regionally-based management approaches with careful consideration of local stock contingents. Future monitoring and research priorities should focus on the identification of reproductive potential, dispersal pathways and settlement patterns of stock contingents to inform the dynamics of mixed stock origins across the Patagonian region. While many aspects regarding the stock structure remain unresolved, results derived from the current studies can be used to inform the development of management measures to ensure the continued recovery and sustainable management of Patagonian toothfish within the region. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2022
- Full Text:
- Date Issued: 2022-10-14
Succession politics and state administration in Africa: the case of Zimbabwe.
- Authors: Chikerema, Arthur Fidelis
- Date: 2021-02
- Subjects: Africa--Politics and government , Public administration , state governments
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/21355 , vital:48494
- Description: The research probes the impact of succession politics on state administration in Africa, Zimbabwe as a case study. Power transition in any political landscape promotes the regeneration and configuration of the political architecture and the functionality of the administrative apparatus of the state. Government performance may thus be viewed as a result of political processes and dynamics that influence governance in a polity. Political succession determines the composition of administrative organs of the state and many political leaders wish to work with administrative apparatus, which are compatible with their ideological orientation. Regular transfer of executive power is the major test of stability, legitimacy and maturity of a nation’s political system, but in Zimbabwe, political leaders have shown a consistent trajectory of violating or amending state and party constitutions to prolong their stay in power (Constitutional coup or a third term tragedy). This has been compelled by ruthless silencing of dissent by suffocating political activism culminating in strong personalities and weak institutions. Succession politics in Zimbabwe resembles executive dominance, egocentrism, excessive appointing powers which are compounded by lack of institutional framework for succession. This undermines the professional independence of the bureaucracy, which in turn inhibits the pursuit of sound governance. Therefore, passing the baton to the next leader has been a challenge; resulting in the personalization of, governments and political parties by leaders. While constitutions provide for elective congress for purposes of electing party leadership and/ or renewing their mandates, there is strong literature pointing to the capture of representative institutions such as Parliaments through strong normative values by leaders. This erodes the role of Parliaments or congresses as a democratic institution, as leaders have used it to “endorse” themselves. The research examines the influence of succession politics on state administration, especially on how the institution of the state and party politics in Zimbabwe conflate with the public administration system leading to state malfunction. This research adopts a qualitative research design that provides an understanding of underlying reasons, opinions, and motivations on political succession and state administration in Zimbabwe. Data was collected through in-depth interviews, complemented by document review and analyzed through thematic content analysis. The study found out that, despite the existence of the legal frameworks that promote seamless power transition, political, societal and historical factors exacerbate Zimbabwe’s succession dilemma. Colonial legacy, societal laxity, the military factor, capture of state institutions by the political elite, lack of a retirement institutional mechanism, the principle of sovereignty and politicization of the succession process were found as the major hindrances to Zimbabwe’s succession trajectory. It recommends broad based and genuine civil service, electoral, security and political (politics with ethics and values) reforms to dismantle the current legacy imbedded in the political system. , Thesis (PhD) (Public Administration) -- University of Fort Hare, 2021
- Full Text:
- Date Issued: 2021-02
Succession politics and state administration in Africa: the case of Zimbabwe.
- Authors: Chikerema, Arthur Fidelis
- Date: 2021-02
- Subjects: Public administration , State governments
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/21467 , vital:48659
- Description: The research probes the impact of succession politics on state administration in Africa, Zimbabwe as a case study. Power transition in any political landscape promotes the regeneration and configuration of the political architecture and the functionality of the administrative apparatus of the state. Government performance may thus be viewed as a result of political processes and dynamics that influence governance in a polity. Political succession determines the composition of administrative organs of the state and many political leaders wish to work with administrative apparatus, which are compatible with their ideological orientation. Regular transfer of executive power is the major test of stability, legitimacy and maturity of a nation’s political system, but in Zimbabwe, political leaders have shown a consistent trajectory of violating or amending state and party constitutions to prolong their stay in power (Constitutional coup or a third term tragedy). This has been compelled by ruthless silencing of dissent by suffocating political activism culminating in strong personalities and weak institutions. Succession politics in Zimbabwe resembles executive dominance, egocentrism, excessive appointing powers which are compounded by lack of institutional framework for succession. This undermines the professional independence of the bureaucracy, which in turn inhibits the pursuit of sound governance. Therefore, passing the baton to the next leader has been a challenge; resulting in the personalization of, governments and political parties by leaders. While constitutions provide for elective congress for purposes of electing party leadership and/ or renewing their mandates, there is strong literature pointing to the capture of representative institutions such as Parliaments through strong normative values by leaders. This erodes the role of Parliaments or congresses as a democratic institution, as leaders have used it to “endorse” themselves. The research examines the influence of succession politics on state administration, especially on how the institution of the state and party politics in Zimbabwe conflate with the public administration system leading to state malfunction. This research adopts a qualitative research design that provides an understanding of underlying reasons, opinions, and motivations on political succession and state administration in Zimbabwe. Data was collected through in-depth interviews, complemented by document review and analyzed through thematic content analysis. The study found out that, despite the existence of the legal frameworks that promote seamless power transition, political, societal and historical factors exacerbate Zimbabwe’s succession dilemma. Colonial legacy, societal laxity, the military factor, capture of state institutions by the political elite, lack of a retirement institutional mechanism, the principle of sovereignty and politicization of the succession process were found as the major hindrances to Zimbabwe’s succession trajectory. It recommends broad based and genuine civil service, electoral, security and political (politics with ethics and values) reforms to dismantle the current legacy imbedded in the political system. , Thesis (PhD) (Public Administration) -- University of Fort Hare, 2021
- Full Text:
- Date Issued: 2021-02