GILLNET ILLUMINATION REDUCES SEA TURTLE BYCATCH · GILLNET ILLUMINATION REDUCES SEA TURTLE BYCATCH...

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GILLNET ILLUMINATION REDUCES SEA TURTLE BYCATCH John Wang 1 Yonat Swimmer 2 Joel Barkan 3 and Shara Fisler 3 Jeff Mangel 4 and Joanna Alfaro-Shigueto 4 1 University of Hawaii – JIMAR 2 NOAA – Pacific Island Fisheries Science Center 3 Ocean Discovery Institute 4 ProDelphinus

Transcript of GILLNET ILLUMINATION REDUCES SEA TURTLE BYCATCH · GILLNET ILLUMINATION REDUCES SEA TURTLE BYCATCH...

GILLNET ILLUMINATION REDUCES SEA TURTLE BYCATCH

John Wang1 Yonat Swimmer2

Joel Barkan3 and Shara Fisler3 Jeff Mangel4 and Joanna Alfaro-Shigueto4

1University of Hawaii – JIMAR 2NOAA – Pacific Island Fisheries Science Center

3Ocean Discovery Institute 4ProDelphinus

Longline  fisheries  

NOAA – Pacific Islands Fisheries Science Center: Development and Testing of

Bycatch Reduction Technologies (BRTs)

Coastal  Pound  Nets   Coastal  Gillnet  fisheries  

Sensory cues

Visual Auditory

Chemosensory

Behaviors

Electromagnetic

Understanding sensory physiology and behaviors can drive the development of bycatch reduction

technologies (BRTs)

Endangered Species Research (2008)

Coastal gillnet fisheries - Coastal gillnets are a common form of fishing - Problematic due to non-selective impacts - Studies indicate large sea turtle bycatch in some fisheries

Baja California Sur - 800 loggerheads/yr (Peckham et al, 2008) - 68% mortality rate

Northern Peru – 300 sea turtles/yr (Alfaro-Shigueto et al, 2011) - 41% mortality rate

•  Drift gillnet salmon fisheries in Puget Sound, WA

•  Diving birds (Common Murre) are bycatch

•  Exploited visual cues - highly visible netting - upper portion of net

•  Bird interaction rates reduced by 45%

Conservation Biology, 1999

Can we develop visual cues that act as alerts for sea turtles?

Attach lightsticks onto a net - illuminating portions of the net - creating a visual alert

VS

Control Net – not illuminated Activated lightsticks

Lightsticks used to attract fish

Bahia de los Angeles

Punta Abreojos

•  Punta Abreojos – Green turtle (Chelonia mydas) monitoring site that uses large mesh gillnets.

•  Bahia de los Angeles – Commercial gillnet fisheries willing to modify their gillnets (e.g. net illumination) and allow observers onboard.

Punta Abreojos

Research sites along the coast of Baja California

Bahia de los Angeles

N=15

117 turtles

70 turtles

Mean CPUE decreased by 40%

Net illumination reduces C. mydas catch rates

Wilcoxon Matched-Pairs Signed-Rank test, significance: *P<0.05 Wang et al (2010) MEPS

N=6

81 turtles

34 turtles

Mean CPUE decreased by 59%

LED lightsticks

Chemical lightsticks

N=15

117 turtles

70 turtles

N=23 N=23

Mean CPUE decreased by 40%

Net illumination reduces C. mydas catch rates

Wilcoxon Matched-Pairs Signed-Rank test, significance: *P<0.05 Wang et al (2010) MEPS

N=6 N=17 N=17

81 turtles

34 turtles

Mean CPUE decreased by 59%

Chemical lightsticks

LED lightsticks

What about other wavelengths?

Electro-retinographs studies with sea turtles and fish

Loggerheads and Leatherbacks Summer flounder (P. dentatus)

Adapted from Horch et al, 2011 Adapted from Horodysky et al, 2010

N=11

209 turtles

123 turtles

N=36 N=36

ns

ns

Wilcoxon Matched-Pairs Signed-Rank test, significance: *P<0.05 Wang et al., (2013) Biology Letters.

Mean CPUE decreased by 40%

*

UV net illumination reduces sea turtle interactions

N=11

209 turtles

123 turtles

N=36 N=36

ns

ns

Wilcoxon Matched-Pairs Signed-Rank test, significance: *P<0.05 Wang et al., (2013) Biology Letters.

Mean CPUE decreased by 40%

*

UV net illumination reduces sea turtle interactions

All elasmobranch catch (all the sharks, rays, guitar fish, torpedo rays) had a significant difference in catch between the two net treatments

If we look just at the sharks – we see also a significant difference with the mean CPUE in the experimental nets

If we looked at the scalloped hammerhead sharks (S. lewini) – we also see a significant difference in catch rates.

I.  Peruvian coastal gillnet fishery - Northern Peru (Constante) bottomset gillnets - 300+ sea turtles/year

- Collaboration with ProDelphinus

II. Indonesian coastal gillnet fishery - West Kalimantan (Borneo)

- Fishery occurs off major nesting beach - Collaboration with WWF-Indonesia,

Indonesia’s Ministry of Marine Affairs and Fisheries (IMMAF), Bogor University

Testing net illumination in coastal gillnet fisheries

A. Key Developments in Peru

-  Tested control nets versus nets illuminated by green LED lights (10m) -  Completed 114 paired trials - Show no change in target catch rates (guitarfish, rays, Pacific halibut) - Illuminated nets had significant decreases in catch rates for: Green sea turtles, cormorants, and sea horses.

- Collaboration with WWF - Indonesia - Rapid assessment of a coastal fishery indicates: - Operates off a major sea turtle nesting beach - Sets are in a leatherback foraging region - Interact with green, leatherback, hawksbill, olive ridley sea turtles - Other bycatch species include finless

porpoise, Irrawaddy dolphin, whale sharks, and other elasmobranchs

-  In 2013, conducted a Fisheries Bycatch Workshop - Brought together Indonesia’s MMAF,

fishermen, fishery academics, NGOs - Designed an initial net illumination trial for 2014

B. Key Developments in Indonesia

Ongoing and Future Research

1.  Baja, MX: Examine how different wavelengths can be used to change the catch composition

Continue to develop novel sensory based BRT in gillnet fisheries using visual and auditory cues

2.  Peru: Move from the testing phase to an adoption phase

Extend research from small coastal fisheries into larger drift gillnet fisheries

3.  Indonesia: Conduct net illumination trials through 2014 - Establish baseline data on bycatch - Test the applicability of net illumination Conduct rapid assessment of additional

coastal gillnet fisheries

Funders:

WWF-Smartgear NOAA-FIsheries-Office of International Affairs, NOAA-PIFSC, NOAA-SWRO, NOAA-PIRO, NOAA-BREP NOAA – Office of Education, University of Hawaii FDRP, Ocean Discovery Institute Supporters,

Fishers: Fishers and community of Punta Abreojos and Bahía de los Angeles Grupo Tortugero de las Californias, Baja California Fishers and community of Constante, Peru Fishers and community of Paloh, West Kalimantan

Special Thanks to: CONANP, IMARPE, IMMAF, I. Kelly, C. Fayh, C. Godinex-Reyes, B. Higgins, E. Kane, D. Lawson, M. Lopez, K. Dean, J. Rodriguez, A. Salazar, J. Sandoval, J. Seminoff, E. English, L. Benaka, K. Bigelow, C. Boggs, T.T. Jones, H. Peckham, Pro Delphinus, WWF-Indonesia, Grupo Tortugero, N. Marcovaldi, B. Giffoni, I. Mustahofa, A. Gautama.

ODI Staff and Students of Hoover High School (San Diego, CA)

Acknowledgements

Cost of net illumination has decreased

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2010 LP Swordfish

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2010 Korean

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2011 Chinese LL LEDs

2010 Shallow fishing LEDs

2011 Shallow fishing LEDs

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