Spain Cooperative Research

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Collaborative mitigation research for pelagic longline fisheries in South Africa

Ed Melvin and Troy Guy, Washington Sea Grant, University of Washington,

and Lorraine B. Read , TerraStat Consulting Group


Principles of Collaborative Research • Test fishermen’s ideas with fishermen – fishermen invested in the

outcome • Demonstrate mitigation strategies reduce bird interactions and are practical and safe • Results in proof at two level: – Fishermen know measures work – seen with their own eyes

– Managers know measures work – researchers produce solid scientific proof with data and analysis


Research Goal – collaborative research in pelagic longline fisheries • Develop a bird-scaring line (tori line) for pelagic longline fisheries for

application in tRFMO fisheries • Test tori lines where bird interaction are very high and most difficult – Southern Hemisphere

• Do research on fishing vessels typical of the high-seas Asian fleets • Do research in a fishery with strong support from fishery managers,

fishing industry, observer program, and other partners


South African Tuna Joint Venture Fishery • Three year research program • Year one: pilot studies in New Zealand and South Africa • Year two: Test two streamer line designs and introduce branchline weighting • Year three: Test weighted branchlines and night setting with two hybrid streamer lines


Unweighted branchlines sink 300 m beyond the vessel – an area too big to protect with bird scaring lines

Unprotected by bird scaring line

300 m bait access • Clear need to weight branchlines • Shrink and Defend: Shrink the area astern that requires defending with streamer lines


Hybrid Bird-Scaring Lines: The Concept Aerial extent is the section that scares birds - must span the area birds are vulnerable to hooking

Bait Access

100 m achieved with experimental weighting in 2009 (60 g w/in 2 m of the hook)


Packing straps create drag to maintain aerial extent of 100 m


2010 Comparisons • Three mitigation measures – W vs. UW branchlines – Night vs. Day – With two hybrid streamer lines

• Two vessels production fishing • South Africa in Austral Winter – worst case interactions with aggressive A & P


Double-Weight Branchline Section alternative to weighted sivels which are potentially dangerous

Developed by Fishing master Yamazaki-san Coated Wire

Kodo

1m to 1.5 m weighted section inserted 2 m above the hook Total weight 65 to 70 g Within 3 to 3.5 m of the hook Multiple weights – one sliding Non-stretch weighted lines (vs mono = rubber band)


monofilament lead-core line (Kodo)

weighted section

weights

monofilament


Hybrid Streamer Line

Aerial Extent = 100m 50m

In-Water Extent = 100m 100m

150m

200m


Attack rate diving seabirds: weighted vs. un-weighted

25,000

aerial extent Average attacks per 1000 hooks

20,000 Unweighted

Weighted

15,000

10,000

5,000

0,000 25

50

75

100

Distance Astern (m)

125

150

200


Bird Mortality


Fish Catch

Fish/ 1,000 hooks

16.00 h 14.00

un-weighted

12.00

weighted

10.00 8.00 6.00 4.00 2.00 0.00 Billfis es

Albacore

Bigeye

Yellowfin

Total

generalized linear fixed effects model with observation and day as random effects


Weighted Branchlines + 2 SLs • Sink faster ~ 70 m • fish catch little to no effect (two years now) • seabird mortality rate reduced 8 fold; • Attack rates reduced 4 fold • Night mortality = o

• Relatively safe - no injuries


Relevance to tRFMOs 2 Hybrid streamer lines (100 m aerial extent) + weighted branchlines +

night setting = Best-practice mitigation in SA EEZ and other white-chinned petrel dominated systems/ southern hemisphere


Acknowledgments

• The Japan Tuna Fisheries Co-operative Association • South Africa Marine and Coastal Management Pelagic and High Seas Fisheries Management Division

• Tuna South Africa • Japan Marine and CapFish • The David and Lucile Packard Foundation and Washington Sea Grant • BirdLife Albatross Task Force and WWF