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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
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