Do marine protected areas increase fishery yield? A study using experimental microcosms and protist populations.

  • Olly A L Hines

Student thesis: Master's ThesisMaster of Science by Research (MScR)

Abstract

Marine protected areas (MPAs) are expected to be applied to a broad range of abiotic and biotic factors, and therefore ecosystem conditions, to deescalate over-exploitative practices that are threatening global levels of marine biodiversity and ecosystem functioning. Yet controversy and discourse remain on how this tool can match local access to benefits gained from ecosystem services with the global need to conserve marine areas to a much stronger degree. The first chapter of this thesis assesses this in depth in the form of a literature review, finding that whilst globally MPA coverage has increased, the number of unsustainably managed fishery stocks has also. Stakeholders linked with fisheries also remain hesitant to implement stronger protection of areas, due to the loss of fishing grounds. A second chapter then examines the implementation of MPAs and ‘buffer zones’ in an experimental setting, whereby a standardized ‘unsustainable’ level of harvesting effort was redistributed across a ‘landscape’. The biomass of protist populations was tracked over time and subsequently analysed in generalised linear models. Different MPA strategies correlated with changes in biomass levels and body-size distributions of populations. Implementing fully and strongly protected MPAs was associated with the greater recovery of landscape-level biomass and biomass which could be termed ‘fishable’, under a greater unsustainable total harvesting effort. There were largely non-significant differences between strategies when a lower total harvesting effort was present. Whilst this study was conducted in an experimental environment where many variables could be controlled, similarities could be seen between these populations and real-world fishery systems. These results showcase how fishery yields can be maintained despite a restriction of access and thus the wider adoption of marine protection measures to reduce the changes of future ecosystem losses.
Date of Award5 Dec 2023
Original languageEnglish
Awarding Institution
  • University of Bristol
SupervisorChris F Clements (Supervisor)

Keywords

  • experimental ecology
  • Ecology
  • marine ecology
  • Conservation
  • fisheries
  • Machine learning
  • biomass
  • marine protected areas
  • MPA
  • Protists
  • ComTrack
  • fishery yield
  • paramecium caudatum

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