Derivation of Shadow Price of Sea Turtle Derivation of Shadow Price of Sea Turtle Bycatch in Hawaii-based Longline Fisheries: Bycatch in Hawaii-based Longline Fisheries:
An Input Distance Function ApproachAn Input Distance Function Approach
Hui Huang & PingSun LeungHui Huang & PingSun LeungUniversity of Hawaii at ManoaUniversity of Hawaii at Manoa
Interaction Between Hawaii-basedInteraction Between Hawaii-based Longline Gear and Sea Turtles Longline Gear and Sea Turtles
Sea turtle conservation: one of the most important issues Sea turtle conservation: one of the most important issues facing Hawaii-based longline fisheries facing Hawaii-based longline fisheries
Swordfish and Mixed-target fishing: Swordfish and Mixed-target fishing: shallow sets; high rate of turtle captureshallow sets; high rate of turtle capture
Tuna-target fishing:Tuna-target fishing: deep sets; relatively less interactionsdeep sets; relatively less interactions
Turtle Catches by Trip Types, 1991-1999Turtle Catches by Trip Types, 1991-1999
92.43%482113751991-1999
92.11%658121999
89.80%1054341998
91.30%430121997
89.66%940381996
85.71%98461995
96.92%22611994
96.10%33711993
96.92%26571992
94.74%310441991
% of Swordfish and MixedTunaMixedSwordfishLand Year
Source: Observer’s Report, Honolulu Laboratory, NMFS (1991-1999)
Longline Fishing Restricted AreasLongline Fishing Restricted AreasArea A: 44 N-28N, 168 W-150 W
No Fishing allowed
Area B: 44 N-28 N, 173 E-168 W
& 150 W-137 W
Restricted longline fishing
100% observer coverage
Area C: 28 N-Equator, 173 E-137 W
Only tuna-trip is allowed
Area A : Closed throughout the year
Area B & C: Closed from March 15,
until May 31
Swordfish Ban and ResumptionSwordfish Ban and Resumption
2001, NMFS’ preferred alternative:2001, NMFS’ preferred alternative: swordfish-style fishing is prohibited; an area (15-0 North, 145-180 swordfish-style fishing is prohibited; an area (15-0 North, 145-180
W) is closed for April and MayW) is closed for April and May. .
April 2004, Swordfish-style fishing return:April 2004, Swordfish-style fishing return:
fewer fishing days; observers on board at all times; strict limits on fewer fishing days; observers on board at all times; strict limits on the number of turtles (16 leather-back turtles, 17 loggerhead the number of turtles (16 leather-back turtles, 17 loggerhead turtles)turtles)
Research Objectives:Research Objectives: To Introduce an alternative method of calculating cost of sea turtle To Introduce an alternative method of calculating cost of sea turtle
protectionprotection To deduce trip-specific shadow price of sea turtle bycatchTo deduce trip-specific shadow price of sea turtle bycatch To compare shadow prices of sea turtle bycatch of various To compare shadow prices of sea turtle bycatch of various
periods, locations, and trip typesperiods, locations, and trip types
General idea of the methodology:General idea of the methodology: Distance function: used in deducing shadow prices for pollutants Distance function: used in deducing shadow prices for pollutants
(e.g. Fare & Grosskopf, 1993; Cogins and Swinton, 1996)(e.g. Fare & Grosskopf, 1993; Cogins and Swinton, 1996) General idea: Dual Shephard’s lemma yields cost-related shadow General idea: Dual Shephard’s lemma yields cost-related shadow
prices of undesirable output (prices of undesirable output (seasea turtle bycatchturtle bycatch) from the input ) from the input distance functiondistance function
Previous StudiesPrevious Studies Curtis and Hicks (2000)Curtis and Hicks (2000) Chakravorty and Nemoto (2000)Chakravorty and Nemoto (2000) implicit prices of sea turtle bycatch ; implicit prices of sea turtle bycatch ; overall welfare foregone from regulatory policiesoverall welfare foregone from regulatory policies
Present WorkPresent Work No need to specify regulatory constraintsNo need to specify regulatory constraints Modest data requirementModest data requirement Flexibility for comparing shadow prices by trip Flexibility for comparing shadow prices by trip
characteristics: time; areas; trip typescharacteristics: time; areas; trip types
Input Distance FunctionInput Distance Function
xo/Di(uo,xo )
x1
x2
xo
L(uo)
}),,()(:{max),,( RtuLxtxuD
Maximum amount of the input vector can be Maximum amount of the input vector can be
deflated, keeping the output vector in the deflated, keeping the output vector in the technology settechnology set
Dual to cost function according to Shephard’s Dual to cost function according to Shephard’s LemmaLemma
FOC: how many units of desirable output FOC: how many units of desirable output (swordfish) would be willing to forego to reduce (swordfish) would be willing to forego to reduce one sea turtle bycatchone sea turtle bycatch
Swordfish observed price= shadow price Swordfish observed price= shadow price derive shadow price for sea turtlederive shadow price for sea turtle
j
iji utxuD
utxuDrr
/),,(/).,(.**
Functional form to derive value of distance functionFunctional form to derive value of distance function
Translog functional formTranslog functional form
n=1,2: trip length (days, weighted by net tons), hooks in that trip (1,000) n=1,2: trip length (days, weighted by net tons), hooks in that trip (1,000) m=1,2,3: swordfish catch, tuna catch, catch of other species (1,000 m=1,2,3: swordfish catch, tuna catch, catch of other species (1,000
pounds)pounds) m=4: number of sea turtlem=4: number of sea turtle
m
M
mmtn
N
nntttt
m
N
n
M
mnnmmm
M
m
M
mmm
n
N
nn
M
nnnm
M
mm
N
nnn
utxttt
uxuu
xxuxtxuLnD
lnln21.
lnln21lnln
21
lnln21lnln),,(
11
2
1 1'
1 1''
'1 1'
'11
0
Estimation of ParametersEstimation of Parameters
Subject toSubject to C1C1
C2C2
C3C3
C4C4
C5aC5a
C5bC5b
C5cC5c
C5dC5d
C6aC6a C6bC6b
212
1),,( ),,(lnk
txuDMinimize
,0),,(ln txuD
0),,(ln
nxtxuD
0),,(ln
mutxuD
0),,(ln
mutxuD
12
1
n
n
02
1'
nnn
02
1
n
nm
02
1
n
nt
nnnn ''
mmmm ''
C1: value of input distance function >=1
C2: non-decreasing in inputs
C3: non-increasing in desirable outputs
C4:non-decreasing in undesirable output
C5: linear homogeneity in inputs
C6: parameter symmetry conditions for translog function
Descriptive statistics of variables included in the analysisDescriptive statistics of variables included in the analysis (54 vessels, 212 obs., 1991-1999) (54 vessels, 212 obs., 1991-1999)
1011.411.84Turtle (number)
Undesirable Outputs
9.4601.401.18Other (thousand pounds)16.0903.454.13Tuna (thousand pounds)66.390.6212.2920.42Swordfish (thousand pounds)
Desirable Outputs
25.400.755.1012.63Hooks (thousands)
55.740.4112.9521.63Trip Length (days standardized by net tons)
Inputs
MaxMinStd. Dev.MeanVariable (units) |
Fish Abundance Effects on OutputsFish Abundance Effects on Outputs
Catch of different species is sensitive to harvestable Catch of different species is sensitive to harvestable stocksstocks
Abundance indices for the species in different periods Abundance indices for the species in different periods and areas are indicators of resource conditions and areas are indicators of resource conditions
Weigh each output of every trip by abundance indicesWeigh each output of every trip by abundance indices
Abundance Indices DerivationAbundance Indices Derivation
Seemingly Unrelated Regression (SUR); analyze catch rates with Seemingly Unrelated Regression (SUR); analyze catch rates with assumption of lognormal error distributionsassumption of lognormal error distributions
Explanation variables: Year, Month, Vessel classes, Regions, Trip Explanation variables: Year, Month, Vessel classes, Regions, Trip typestypes
: expected catch rate for vessel length c in month s of year y in region a by trip type q.
: catch rate obtained by a tuna trip of vessel 1 in January 1991 in area 1.
: vessel classes; : month; : year; : trip types; : region.
csyqaaqysccsyqa ln
Yearly Average Technical Efficiency and Shadow PricesYearly Average Technical Efficiency and Shadow Prices
Chakravorty and Nemoto (2000Chakravorty and Nemoto (2000)): $14,000 in 1995 USD ( $12,343 in 1991 dollars) per loggerhead turtle; use number (66) (Kleiber,1998)
Curtis and Hicks (2000): $41,262 per turtle from seasonal closure and $ 52, 976 per turtle; =$33,843 (seasonal) and $43,509 (full) in 1991 USD
Pradham and Leung (2004): Between $35,000-$55,000 per sea turtle
32,5610.67071991-1999
16,4960.69481999
23,0230.65501998
16,9010.60651997
24,2320.73781996
34,2440.72711995
38,1720.63291994
27,0820.56721993
33,5150.67341992
37,2430.76581991
Shadow Prices(in 1991 USD)
Technical EfficiencyLanding year
Shadow Prices by Trip TypesShadow Prices by Trip Types
17,50214,2331999
18,26232,5451998
17,87410,0841997
25,16123,5091996
31,99434,8441995
9,26539,3281994
18,61027,8301993
26,53434,5731992
20,76939,5971991
Shadow Price(in 1991 USD)
Shadow Price (in 1991 USD)Landing Year
MixedSwordfish
Shadow prices by monthShadow prices by month
26,08626,0861212
40,37340,3731111
8,4168,4161010
33,79533,79599
22,70922,70988
23,63123,63177
34,87434,87466
48,96148,96155
41,43241,43244
32,83632,83633
23,87523,87522
13,36313,36311
Shadow PricesShadow Prices(in 1991 USD)(in 1991 USD)Landing MonthLanding Month
Sea turtle catch and Shadow Price by areasSea turtle catch and Shadow Price by areas
1120,532168,931817,5021999
345,4382516,3152620,4871998
132,578421,819109,2921997
231,2001722,0821625,3161996
538,2861337,462926,7241995
320,7622633,7421847,7531994
533,3844323,5342130,3701993
1521,3571641,8382635,2821992
841,728843,1322632,7911991
NumberShadow Price(in 1991 USD)
NumberShadow Price(in 1991 USD)
NumberShadow Price(in 1991 USD)
Landing Year
Area CArea BArea A
ConclusionsConclusions $32,651 (1991 USD) per turtle, close to Curtis & Hicks $32,651 (1991 USD) per turtle, close to Curtis & Hicks
(2000) and Pradham & Leung (2004) estimates, higher (2000) and Pradham & Leung (2004) estimates, higher than Chakravorty and Nemoto (2000) estimate than Chakravorty and Nemoto (2000) estimate
Not assuming policy implementation; modest data Not assuming policy implementation; modest data requirement; information for trade-offs between incidental requirement; information for trade-offs between incidental capture and costs of bycatch abatementcapture and costs of bycatch abatement
Reveal variation pattern by trip characteristicsReveal variation pattern by trip characteristics
Shortcoming: nonstochasticShortcoming: nonstochastic
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