Mitigating Seabird Mitigating Seabird Interactions with - - PowerPoint PPT Presentation

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Mitigating Seabird Mitigating Seabird Interactions with - - PowerPoint PPT Presentation

May 06, 2023 374 likes •731 views

Mitigating Seabird Mitigating Seabird Interactions with Interactions with Trawl Nets Trawl Nets Clement & Associates Ltd FISHERIES ADVISORS & ANALYSTS Objectives Objectives Characterise the nature and extent of

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SLIDE 1

Mitigating Seabird Interactions with Trawl Nets Mitigating Seabird Interactions with Trawl Nets

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

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SLIDE 2

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

Objectives Objectives

  • Characterise the nature and extent of

interactions of seabirds attracted to trawl nets (NIWA Report 2008)

  • Identify ways to avoid or reduce these

interactions (Workshop 6 May 2008)

  • Trial methods with potential to reduce these

interactions (focus of today's presentation)

  • Characterise the nature and extent of

interactions of seabirds attracted to trawl nets (NIWA Report 2008)

  • Identify ways to avoid or reduce these

interactions (Workshop 6 May 2008)

  • Trial methods with potential to reduce these

interactions (focus of today's presentation)

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SLIDE 3

Trial Methods Trial Methods

  • Trial two methods with potential to

reduce seabird net captures by reducing volume of netting on the water surface

  • 1. Turning the vessel while hauling
  • 2. Net binding when shooting
  • Trial two methods with potential to

reduce seabird net captures by reducing volume of netting on the water surface

  • 1. Turning the vessel while hauling
  • 2. Net binding when shooting

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

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SLIDE 4

Please note: No seabirds were harmed during these trials! Please note: No seabirds were harmed during these trials!

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

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SLIDE 5

Turning while hauling Turning while hauling

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

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SLIDE 6

Net binding Net binding

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

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SLIDE 7

Net binding Net binding

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

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SLIDE 8

Sea Trials Completed Sea Trials Completed

  • FV Taimania – Hoki Fishery Cook

Strait September 2008

  • FV Aleksandr Buryachenko – Jack

Mackerel Fishery West Coast North Island December 2008

  • FV Taimania – Hoki Fishery Cook

Strait September 2008

  • FV Aleksandr Buryachenko – Jack

Mackerel Fishery West Coast North Island December 2008

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

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SLIDE 9

FV Taimania FV Taimania

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

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SLIDE 10

FV Taimania FV Taimania

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

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SLIDE 11

FV Aleksandr Buryachenko FV Aleksandr Buryachenko

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

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SLIDE 12

FV Aleksandr Buryachenko FV Aleksandr Buryachenko

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

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Trial Areas Trial Areas

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

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SLIDE 14

Turning the Vessel Turning the Vessel

  • These vessels must turn 5° to 10° helm when

hauling to get the net onto deck correctly

  • This does close up the volume of mesh – but

the turn is not continuous – the net must be hauled straight at times especially at start

  • Couldn’t complete trial on either vessel – as

both must turn vessel every haul, no control treatment was possible

  • These vessels must turn 5° to 10° helm when

hauling to get the net onto deck correctly

  • This does close up the volume of mesh – but

the turn is not continuous – the net must be hauled straight at times especially at start

  • Couldn’t complete trial on either vessel – as

both must turn vessel every haul, no control treatment was possible

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

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SLIDE 15

FV Taimania (see video) FV Taimania (see video)

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

  • Fleeted onto net roller
  • Fleeted onto net roller
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SLIDE 16

FV A Buryachenko FV A Buryachenko

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

  • Two nets fleeted on each side of deck
  • Two nets fleeted on each side of deck
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SLIDE 17

Net Binding Net Binding

  • Net binding can be competently and safely

carried out onboard using midwater nets

  • The ties have to have the correct holding

force – different holding force for different parts of the net

  • Could not bind head of trawl – too much

force

  • Gave up on breaking binds
  • Net binding can be competently and safely

carried out onboard using midwater nets

  • The ties have to have the correct holding

force – different holding force for different parts of the net

  • Could not bind head of trawl – too much

force

  • Gave up on breaking binds

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

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SLIDE 18

Net bind Net bind

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

  • Fixed twine bind with twist knot
  • Fixed twine bind with twist knot
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SLIDE 19

Net with binds being shot away Net with binds being shot away

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

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SLIDE 20

Net without binds being shot away Net without binds being shot away

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

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SLIDE 21

Show videos Show videos

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

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Net Binding - issues Net Binding - issues

  • Need a balance between holding

netting long enough vs not releasing

  • May not release because:
  • Binding too tight / too many twists
  • Frayed rope not coming undone
  • Need a balance between holding

netting long enough vs not releasing

  • May not release because:
  • Binding too tight / too many twists
  • Frayed rope not coming undone

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

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FV Taimania FV Taimania

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

  • Trawl net still closed on haul
  • Trawl net still closed on haul
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Frayed rope Frayed rope

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

  • The culprit
  • The culprit
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Results of Net Binding Results of Net Binding

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

Net Failed to open during tow 1 3 15 3 4 Mussel lash 12 4 15 3 4 Mussel lash 10 4 15 3 4 Mussel lash 6 4 (all broke) 15 Tied 4 Cotton 5 1 3 15-20 3 4 Mussel lash 3 Broken/Failed/Held Net Closed Let Go Loose Held Intervals between binds (m) Twists in Bind Diameter Bind Type Performance Binding Information Tow # FV A. Taimania 1 4 6 Sisal 1 10 8-10 3 6 Mussel lash 21 4 7 PPE 2 10 8-10 3 5 Mussel lash 19 4 6 PPE 10 9-10 3 5 Mussel lash 16 4 5 PPE 10 10 3 5 Mussel lash 13 1 1 8 10 3 10 Mussel lash 6,10,12 2 6 10-12 3 8 Mussel lash 4 Broken/Failed/Held Net Closed Let Go Loose Held Intervals between binds (m) Twists in Bind Diameter Bind Type Performance Binding Information Tow # FV A. Buryachenko

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Bird Behaviour – FV Taimania Bird Behaviour – FV Taimania

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

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Bird Behaviour – FV Taimania Bird Behaviour – FV Taimania

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

FV Taimania

20 40 60 80 100 120 140 160 180 Small Albatross Cape Petrel Other Seabirds Types of Seabirds Number of Seabirds Hauling Shooting

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Bird Behaviour – FV A Buryachenko Bird Behaviour – FV A Buryachenko

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

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Bird Behaviour – FV A Buryachenko Bird Behaviour – FV A Buryachenko

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

FV Aleksandr Buryachenko

5 10 15 20 25 30 Small Albatross Cape Petrel Other Seabirds Types of Seabirds Number of Seabirds Hauling Shooting

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  • Both vessels must turn to get net
  • nboard
  • The net must haul headline straight on

(30% of haul time)

  • Both vessels must turn to get net
  • nboard
  • The net must haul headline straight on

(30% of haul time)

Can Turning the Vessel Reduce Seabird Captures? Can Turning the Vessel Reduce Seabird Captures?

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

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SLIDE 31

Can Turning the Vessel Reduce Seabird Captures? Can Turning the Vessel Reduce Seabird Captures?

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

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  • Turning the vessel does reduce

exposed netting on rest of trawl

  • Turning the vessel does reduce

exposed netting on rest of trawl

Can Turning the Vessel Reduce Seabird Captures? Can Turning the Vessel Reduce Seabird Captures?

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

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  • Obviously only on shooting
  • More seabirds about on hauling
  • Cleaning net of stickers before shooting may

be more effective

  • Bottom trawls not tested
  • Apparent that at times not required
  • Would be good contingency measure
  • Obviously only on shooting
  • More seabirds about on hauling
  • Cleaning net of stickers before shooting may

be more effective

  • Bottom trawls not tested
  • Apparent that at times not required
  • Would be good contingency measure

Can Net Binding Reduce Seabird Captures? Can Net Binding Reduce Seabird Captures?

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

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  • Will not stop seabirds diving into
  • pening of net
  • On haul
  • Midwater head section can’t be bound
  • Bottom trawls not tested but suspect

same issues

  • Will not stop seabirds diving into
  • pening of net
  • On haul
  • Midwater head section can’t be bound
  • Bottom trawls not tested but suspect

same issues

Can Net Binding Reduce Seabird Captures? Can Net Binding Reduce Seabird Captures?

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS

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SLIDE 35

Clement & Associates Ltd

FISHERIES ADVISORS & ANALYSTS