Spain Cooperative Research

Page 1

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


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



Hybrid Streamer Line

Aerial Extent = 100m 50m

In-Water Extent = 100m 100m



Attack rate diving seabirds: weighted vs. un-weighted


aerial extent Average attacks per 1000 hooks

20,000 Unweighted





0,000 25




Distance Astern (m)




Bird Mortality

Fish Catch

Fish/ 1,000 hooks

16.00 h 14.00




10.00 8.00 6.00 4.00 2.00 0.00 Billfis es





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


• 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