E-Thesis 197 views
Estimating production of finfish in saltmarshes on the South Wales coast / SASHA SHUTE
Swansea University Author: SASHA SHUTE
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...
| Published: |
Swansea University, Wales, UK
2025
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| 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 |
| 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 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. |
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| Item Description: |
A selection of content is redacted or is partially redacted from this thesis to protect sensitive and personal information. |
| Keywords: |
Saltmarsh, Finfish, Production, Managed realignment, Increment Summation Method, Estuarine habitats, Fish nursery habitat. |
| College: |
Faculty of Science and Engineering |
| Funders: |
Natural Resources Wales |