An

ecological risk assessment

for the effect of the Korean tuna

longline

fishery

in the Western and Central Pacific Ocean

An

ecological risk assessment

for the effect of the Korean tuna

longline

fishery

in the Western and Central Pacific Ocean

You Jung Kwon1,2, Doo

Hae

An2, Chang Ik

Zhang1, Dae

Yeon

Moon2

and Jae Bong Lee2

1Pukyong National University, Korea , 2National Fisheries Research & Development Institute, Korea

ScopingScoping

Level 1

Level 2

Level 3

Risk

Man

agem

ent

Resp

onseL H

L H

L H

Ecological risk assessment Ecological risk assessment

(Smith et al, 2007)

ScopingScoping

Level 1

Level 2

Level 3

Risk

Man

agem

ent

Resp

onseL H

L H

L H

Comprehensive

Focused

Time & $$

Time & $$

Uncertain

More certain

Qualitative

Quantitative

(qualitative analysis)

(semi-quantitative analysis)

(quantitative analysis)

Level 2: PSA (Productivity and Susceptibility Analysis)Level 2: PSA (Productivity and Susceptibility Analysis)

Productivity, r- recovery rate after potential depletion or damage by the fishing

activity

qEBKBrB

dtdB

−−= )1(

Susceptibility, q- extent of the impact due to fishing activity

Assessment on the adverse impacts of the Korean tuna longline

fishery in the Western and Central

Pacific Ocean

PurposePurpose

-

target species, non-target species and dependent or associated with the target species

-

protect biodiversity in the marine environment

Precautionary approach for the stock or ecosystem management and conservation-

identification of non-target species for consideration of future research or management

DataDataSurvey area

N60o

60o

S

40o

40o

20o

20o

0o

140o120o100o 100o120o140o160o180o160oE W80o

WCPO EPO

2005

20062007-2008

2007 2005

2006

Period: 2005-2008

-

20,157 catches in number

-

48 species

Area: Western and Central Pacific OceanSource:

Collected data by 7 scientific observers from NFRDI in Korea

SpeciesSpeciesGroup English name Scientific name

Tunas(5)

Albacore Thunnus alalunga

Bigeye

tuna Thunnus obesus

Yellowfin

tuna Thunnus albacares

Skipjack tuna Katsuwonus pelamis

Bluefin

tuna Thunnus thynnus

Billfishes(6)

Swordfish Xiphias gladius

Shortbill

spearfish Tetrapturus angustirostris

Blue marlin Makaira mazara

Indo-Pacific sailfish Istiophorus platypterus

Striped marlin Tetrapturus audax

Black marlin Makaira indica

Sharks(13)

Bigeye

thresher shark Alopias superciliosus

Blue shark Prionace glauca

Galapagos shark Carcharhinus galapagensis

Longfin

mako Isurus paucus

Shortfin

mako Isurus oxyrinchus

Oceanic whitetip

shark Carcharhinus longimanus

Grey reef shark Carcharhinus amblyrhynchos

Smooth hammerhead Sphyrna zygaena

Crocodile shark Pseudocarcharias kamoharai

Scalloped hammarhead

shark Sphyrna lewini

Japanese velvet dogfish Zameus ichiharai

Salmon shark Lamna

ditropis

Silky shark Carcharhinus falciformis

SpeciesSpeciesGroup English name Scientific name

Turtles(3)

Green sea turtle Chelonia mydas

Loggerhead sea turtle Caretta caretta

Olive ridley

sea turtle Lepidochelys olivacea

Other species(21)

Sickle pomfret Taractichthys steindachneri

Black pomfret Taractes rubescens

Escolar Lepidocybium flavobrunneum

Snake mackerel Gempylus serpens

Wahoo Acanthocybium solandri

Longnose

lancetfish Alepisaurus ferox

Pelagic stingray Dasyatis violacea

Ocean sunfish Mola mola

Great barracuda Sphyraena barracuda

Opah Lampris guttatus

Dolphinfish Coryphaena

hippurus

Sharptail

mola Masturus lanceolatus

Manta ray Mobula

japanica

Oilfish Ruvettus

pretiosus

Rainbow runner Elagatis

bipinnulata

Slender sunfish Ranzania

laevis

Suck fish Remora remora

Flyingfish Prognichthys gibbifrons

Crested oarfish Lophotus lacepede

Razorback scabbardfish Assurger anzac

Shortnose

lancetfish Alepisaurus brevirostris

Sharks28.8%

Billfishes5.9%

Tunas56.8%

Others8.2%

Turtles0.3%

Indo-Pacificsailfish5.8%

Shortbillspearfish

2.8%

Striped marlin16.5% Black marlin

0.8%

Blue marlin29.6%

Swordfish44.5%

Species composition catch in weightSpecies composition catch in weight

Proportion of captured species (weight) by 7 scientific observations from 2005 to 2008

Others27.9%

Sickle pomfret12.2%

Opah20.7%

Escolar39.3%

Blue shark60.9%

Others9.6%

Mako shark22.9%

Bigeyethresher shark

6.6%

Shortfin mako

Albacore28.5%

Yellowfin10.6%

Bigeye59.4%

Skipjack1.3%

Bluefin0.1%

Targetspecies

57%

Non-target

species43%

Indicators for species components (Target, By-catch, Protected species)

Indicators for species components (Target, By-catch, Protected species)

Productivity attributes

•

Maximum age •

Age at maturity

•

Size at maturity •

Annual fecundity

•

Maximum size•

Reproductive strategy

•

Trophic

level

Susceptibility attributes

•

Overlap with fishing effort

•

Global distribution•

Adult habitat

overlap with

juvenile•

Selectivity

•

Post-capture mortality

SusceptibilitySusceptibility

Sea surface

309m

25m

Maximum hook depth

sp. A

sp. B

sp. C

25m

309m

167m

bottom

0m

Reference point

Species A: High risk (2), 100%Species B: Medium risk (1), 50%Species C: Low risk (0), 0%

Overlap with fishing effort

Attribute

Indicator

AttributesAttributes(CSIRO, 2005)

Attributes Indicators Reference pointsLow (0) Medium (1) High (2)

ProductivityMaximum age (year) < 10 10 –

25 25 <Age at maturity (year) < 5 5 –

10 10 <Size at maturity (cm) < 40 40 -

200 200 <Maximum size (cm) < 100 100 -

300 300 <

Reproductive strategy Broadcast spawners

Demersal spawners Live bearer

Trophic

level < 2.75 2.75 –

3.25 3.25 <

SusceptibilityOverlap with fishing effort (m) 309 < 167 < 25 -

309

Global distribution Worldwide Hemisphere LocalityAdult habitat overlap with juvenile Low rate Medium rate High rate

Selectivity No selectivity for longline

fisheryPost-capture mortality Alive Barely alive Dead

Indicator Ⅰ

Indi

cato

r Ⅱ

High risk

Low risk

TypeⅠ

0

1

2

1 2

Low risk

High riskMedium

risk

TypeⅡ

Attribute ⅠA

ttri

bute

Ⅱ

Ecosystem risk assessmentEcosystem risk assessment

Length at maturity

Capt

ured

mea

n le

ngth

ProductivitySu

scep

tibi

lity

100

200

300Tunas

0

100

200

0 100 200

Billfishes

Sharks

100 200 300

Others

Length at maturity (cm)

Cap

ture

d m

ean

leng

th (c

m)

TypeⅠTypeⅠ

Other species

Productivity

1.0

2.0

0.0 1.0

Sus

cept

ibili

ty

Tunas

1.0 2.0

Billfishes

0.02.0

TypeⅡTypeⅡ2

1

0 1 2 0 1 2

TypeⅡTypeⅡ

TypeⅡTypeⅡ

0

1

2

1 2Productivity

Sus

cept

ibili

ty

tunas

turtles

sharks

billfishes

tunas billfishes

sharks

turtles

Oceanic white-tip Shark

Galapagos shark

Scalloped hammarhead

shark

Longfin

makoBigeye

thresher shark

Blue shark Shortfin

mako

Oceanic white-tip Shark

ConclusionConclusion

Not only target tuna species were influenced by the tuna longline

fishery, but also non-target species were

affected by the fishery

- tunas: medium risk- billfishes: medium or high risk- sharks: high risk- turtles: : medium or high risk- others: medium or high risk

Blue sharkOceanic white-tip sharkShortfin makoThresher shark

WCPFC

Galapagos sharkLongfin makoScalloped hammarhead sharkOceanic white-tip shark

This study

ConclusionConclusion

I.

Development and improvement of long-term data collection, monitoring and research programmes

For reducing non-target species

II.

Enhancement and development of methodology- more robust assessment

III.Identification of captured non-target species by other tuna fisheries such as purse seine or pole-and-line

Provide wider scientific advices to the policy makers and stakeholders