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Estimating production of finfish in saltmarshes on the South Wales coast / SASHA SHUTE

Swansea University Author: SASHA SHUTE

  • E-Thesis – open access under embargo until: 14th March 2026

Abstract

Saltmarshes are widely recognised as important nursery habitats for juvenile fish, yet their contribution to fish production remains underexplored. Globally, saltmarsh habitats have declined by 50%, leading to a rapid expansion of restoration projects. This study estimates annual fish production acr...

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Published: Swansea University, Wales, UK 2025
Institution: Swansea University
Degree level: Master of Research
Degree name: MSc by Research
Supervisor: Esteban, N., and Unsworth, R. K. F.
URI: https://cronfa.swan.ac.uk/Record/cronfa69631
first_indexed 2025-06-05T12:56:09Z
last_indexed 2025-10-31T08:45:19Z
id cronfa69631
recordtype RisThesis
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spelling 2025-10-29T09:42:38.3327204 v2 69631 2025-06-05 Estimating production of finfish in saltmarshes on the South Wales coast 7e20f6634cf1297a3075ebf2e8cee69c SASHA SHUTE SASHA SHUTE true false 2025-06-05 Saltmarshes are widely recognised as important nursery habitats for juvenile fish, yet their contribution to fish production remains underexplored. Globally, saltmarsh habitats have declined by 50%, leading to a rapid expansion of restoration projects. This study estimates annual fish production across three estuarine habitat types: saltmarsh, managed realignment (restored saltmarsh), and unvegetated shores. Monthly seine and fyke net surveys,conducted over 12 months at 17 sites within the Carmarthen Bay estuaries, recorded fish species, abundance, and size. Fish production was quantified using the Increment Summation Method. Six commercially valuable species and three species of conservation interest were identified. European bass contributed 73% (0.06385 g WW m⁻² year⁻¹) of the total annual production (0.0866 g WW m⁻² year⁻¹), showing highest productivity in unvegetated shores. Notably, production of Atlantic herring was measurable only insaltmarsh habitats (0.00443 g WW m⁻² year⁻¹), while production of European eel was restricted to managed realignment sites (0.00035 g WW m⁻² year⁻¹). However, the managed realignment has yet to achieve the full ecological functionality of natural saltmarshes, as evidenced by lower overall fish densities compared to saltmarsh and unvegetated shores (managed realignment: 475 individuals per km²; saltmarsh: 8,596 individuals per km²;unvegetated shores: 5,189 individuals per km²). Four of the six commercially important species exhibited higher production in saltmarsh than in other habitats, underscoring the role of saltmarshes in enhancing finfish productivity. As the first UK study to estimate finfish production in saltmarshes, this research establishes critical baseline data for saltmarsh fish communities in South Wales. The findings highlight the ecological importance of saltmarshes and suggest that the managed realignment must advance further to fully replicate their functionality for fish. E-Thesis Swansea University, Wales, UK Saltmarsh, Finfish, Production, Managed realignment, Increment Summation Method, Estuarine habitats, Fish nursery habitat. 13 3 2025 2025-03-13 A selection of content is redacted or is partially redacted from this thesis to protect sensitive and personal information. COLLEGE NANME COLLEGE CODE Swansea University Esteban, N., and Unsworth, R. K. F. Master of Research MSc by Research Natural Resources Wales Natural Resources Wales 2025-10-29T09:42:38.3327204 2025-06-05T13:39:42.1184050 Faculty of Science and Engineering School of Biosciences, Geography and Physics - Biosciences SASHA SHUTE 1 Under embargo Under embargo 2025-06-05T13:55:21.7657057 Output 2809575 application/pdf E-Thesis – open access true 2026-03-14T00:00:00.0000000 Copyright: The Author, Sasha Shute, 2024 true eng https://creativecommons.org/licenses/by-nc-nd/4.0/
title Estimating production of finfish in saltmarshes on the South Wales coast
spellingShingle Estimating production of finfish in saltmarshes on the South Wales coast
SASHA SHUTE
title_short Estimating production of finfish in saltmarshes on the South Wales coast
title_full Estimating production of finfish in saltmarshes on the South Wales coast
title_fullStr Estimating production of finfish in saltmarshes on the South Wales coast
title_full_unstemmed Estimating production of finfish in saltmarshes on the South Wales coast
title_sort Estimating production of finfish in saltmarshes on the South Wales coast
author_id_str_mv 7e20f6634cf1297a3075ebf2e8cee69c
author_id_fullname_str_mv 7e20f6634cf1297a3075ebf2e8cee69c_***_SASHA SHUTE
author SASHA SHUTE
author2 SASHA SHUTE
format E-Thesis
publishDate 2025
institution Swansea University
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Biosciences, Geography and Physics - Biosciences{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Biosciences, Geography and Physics - Biosciences
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description Saltmarshes are widely recognised as important nursery habitats for juvenile fish, yet their contribution to fish production remains underexplored. Globally, saltmarsh habitats have declined by 50%, leading to a rapid expansion of restoration projects. This study estimates annual fish production across three estuarine habitat types: saltmarsh, managed realignment (restored saltmarsh), and unvegetated shores. Monthly seine and fyke net surveys,conducted over 12 months at 17 sites within the Carmarthen Bay estuaries, recorded fish species, abundance, and size. Fish production was quantified using the Increment Summation Method. Six commercially valuable species and three species of conservation interest were identified. European bass contributed 73% (0.06385 g WW m⁻² year⁻¹) of the total annual production (0.0866 g WW m⁻² year⁻¹), showing highest productivity in unvegetated shores. Notably, production of Atlantic herring was measurable only insaltmarsh habitats (0.00443 g WW m⁻² year⁻¹), while production of European eel was restricted to managed realignment sites (0.00035 g WW m⁻² year⁻¹). However, the managed realignment has yet to achieve the full ecological functionality of natural saltmarshes, as evidenced by lower overall fish densities compared to saltmarsh and unvegetated shores (managed realignment: 475 individuals per km²; saltmarsh: 8,596 individuals per km²;unvegetated shores: 5,189 individuals per km²). Four of the six commercially important species exhibited higher production in saltmarsh than in other habitats, underscoring the role of saltmarshes in enhancing finfish productivity. As the first UK study to estimate finfish production in saltmarshes, this research establishes critical baseline data for saltmarsh fish communities in South Wales. The findings highlight the ecological importance of saltmarshes and suggest that the managed realignment must advance further to fully replicate their functionality for fish.
published_date 2025-03-13T05:28:42Z
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