The Ecology and Distribution of Seabass in the Southwest UK - - PowerPoint PPT Presentation

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the ecology and distribution of seabass in the southwest
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The Ecology and Distribution of Seabass in the Southwest UK - - PowerPoint PPT Presentation

Nov 07, 2022 206 likes •473 views

The Ecology and Distribution of Seabass in the Southwest UK D&S IFCA quarterly meeting The Ecology and Distribution of Seabass in the Southwest UK Sup uperv ervisory sory Team am Na Name Organisa anisation tion Dr Emma Sheehan

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The Ecology and Distribution of Seabass in the Southwest UK

D&S IFCA quarterly meeting

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The Ecology and Distribution of Seabass in the Southwest UK

Sup uperv ervisory sory Team am Na Name Organisa anisation tion

Dr Emma Sheehan Plymouth University Dr Elizabeth West D&S IFCA Tim Robbins D&S IFCA Dr Shaun Plenty Teleost Consulting Prof Martin Attrill Plymouth University

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PhD Context

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Stock Status

With 0 commercial catch in 2017, the North Atlantic stock is predicted to remain below “Blim” in 2018 (ICES, 2016)

PhD: The Ecology and Distribution of Seabass in the Southwest UK

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Dependence on estuaries

PhD: The Ecology and Distribution of Seabass in the Southwest UK

Spawning aggregations Site fidelity Dependence on estuaries

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Estuaries:

  • Highly important ecosystem for

European Seabass

  • Nursery ground
  • Feeding opportunities

Review:

  • Existing management of

European Seabass within and adjacent to estuaries

  • Identify specific habitats or

“features” important for seabass

PhD: The Ecology and Distribution of Seabass in the Southwest UK

Regional management

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Managed Re-alignment fish survey

  • 85% of UK estuaries adapted by land reclamation
  • 25-80% loss in intertidal habitat
  • Estuaries in “Bad and deteriorating” Conservation

Status – EC habitats directive

  • Saltmarsh in “unfavourable status” – EC habitats

directive

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Steart Marsh, Severn Estuary

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Overall Question:

  • Do Managed Re-alignment

schemes provide equivalent habitat to natural saltmarsh

  • Testing for differences between:
  • Fish community
  • Diet & feeding success

Steart Marsh

PhD: The Ecology and Distribution of Seabass in the Southwest UK

Managed Re-alignment Fish Survey

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Managed Re-alignment Fish Survey

Survey Plan:

  • 3 Managed Re-alignment schemes plus natural saltmarsh

PhD: The Ecology and Distribution of Seabass in the Southwest UK

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Managed Re-alignment Fish Survey

PhD: The Ecology and Distribution of Seabass in the Southwest UK

Method:

  • Deploy fyke (a) and seine (b)

nets in Managed Re- alignment and adjacent natural saltmarsh

b – Seine net a – Fyke net a – Fyke net

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Managed Re-alignment Fish Survey

  • Five surveys completed
  • 16 species - nine of

commercial interest: Seabass; Herring; Flounder; Plaice; Sprat Whiting Mullet (3 species)

  • European Eel of

Conservation interest

PhD: The Ecology and Distribution of Seabass in the Southwest UK

Pictures taken at Steart Marsh, Severn Estuary

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Managed Re-alignment Fish Survey

Fish Community

  • Different fish community

captured within Managed Re- alignment than in natural saltmarsh

  • Average diversity higher within

Managed Re-alignment Schemes than natural saltmarsh

PhD: The Ecology and Distribution of Seabass in the Southwest UK

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Managed Re-alignment Fish Survey

Diet: 0+ Seabass

  • MDS plot suggests some

grouping of 0+ European Bass diet

  • 1+ Seabass, TLM and Gobies

captured however not analysed to date

Sample Size - * sample site removed Survey Sample Site Treatment n Steart Marsh BBSSSI Natural 12 HNR* Natural 1 SM MRAS 18 Wallasea Island JM MRAS 8 PCN Natural 13 PCS Natural 27

PhD: The Ecology and Distribution of Seabass in the Southwest UK

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Managed Re-alignment Fish Survey

PhD: The Ecology and Distribution of Seabass in the Southwest UK

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Managed Re-alignment Fish Survey

Summary

  • MRAS do provide habitat for fish:
  • High fish diversity
  • Habitat not currently equivalent to

natural saltmarsh:

  • Different diet
  • Continue monitoring

PhD: The Ecology and Distribution of Seabass in the Southwest UK

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Tracking bass within and adjacent to Estuaries

  • Assess the effectiveness of

designated Bass Nursery Areas

  • Monitor movement with other

fish species

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Tracking

IBASS - Immature Bass

Acoustic Stock Surveillance

  • EMFF funding - £249,000.00
  • Track juvenile European seabass

movement through acoustic telemetry

  • 84 Receivers
  • 150 transmitter tags

PhD: The Ecology and Distribution of Seabass in the Southwest UK

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IBASS - Immature Bass

Acoustic Stock Surveillance

Aim – Monitor movement

across BNA boundary:

1) Identify the frequency of movement outside BNA boundary 2) Help inform BNA demarcation

  • r netting practices in close

proximity

PhD: The Ecology and Distribution of Seabass in the Southwest UK

Tracking

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IBASS - Immature Bass

Acoustic Stock Surveillance

Aim - Monitor movement

patterns within BNA:

1) Track overall movement 2) Correlate movement to environmental variables 3) Identify broad areas of interest for “active tracking” surveys

PhD: The Ecology and Distribution of Seabass in the Southwest UK

Tracking

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Assessing competitive interactions between European Seabass and Gilthead Seabream

  • Salcombe Harbour – Ria system
  • 50 European seabass,
  • 25 Gilthead seabream
  • Gilthead seabream (Sparus aurata)
  • “Recent” colonisation of the south

UK

  • High commercial value
  • Exploit similar habitats to European

seabass

PhD: The Ecology and Distribution of Seabass in the Southwest UK

Tracking

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Assessing spatial overlap between commercial target and non target fish species

  • Taw/Torridge and Dart estuaries
  • 2 Estuaries
  • 100 European Seabass
  • 40 Sea trout (Salmo trutta)
  • Sea trout;
  • Very little information on

estuarine movement,

  • Potential by-catch species with

high recreational value

PhD: The Ecology and Distribution of Seabass in the Southwest UK

Tracking

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Static netting review

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PhD: The Ecology and Distribution of Seabass in the Southwest UK

  • D&S IFCA netting permit bylaw
  • Fixed net headline depth of 3m

within “coastal areas”

  • Migratory salmonids associated

to shallow (0-5m) water depth (Summer, 2015)

  • EA suggested headline depth of

5m

  • Limited supporting evidence

and could reduce catch from net fisheries

Static netting review

Headline depth Reason 0m Control 3m Current headline depth 5m Experimental headline depth

Headline depth

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PhD: The Ecology and Distribution of Seabass in the Southwest UK

  • D&S IFCA netting permit bylaw
  • Fixed net headline depth of 3m

within “coastal areas”

  • Migratory salmonids associated

to shallow (0-5m) water depth (Summer, 2015)

  • EA suggested headline depth of

5m

  • Limited supporting evidence

and could reduce catch from net fisheries

Static netting review

Headline depth Reason 0m Control 3m Current headline depth 5m Experimental headline depth

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Fin . . . .

Comments and suggestions welcome!!

Thomas.stamp@plymouth.ac.uk