Longline CPUE standardization: IATTC 2006

Simon Hoyle and Mark Maunder

Introduction

• Longline fisheries• Indices of abundance• Statistical methods• Results & discussion

– Model selection– Diagnostics– CPUE indices– Compare with last year– Parameter estimates

Longline fisheries

10

40

30

20

10

0

10

20

30

40

150 140 130 120 110 100 90 80 70

11

12

6

5

1, 13

2, 143, 15

4, 16 7

9

8

Baitboat Unassociated Longline

DolphinFloating Objects

Northern

Southern

Indices of abundance

• Standardized CPUE assumed proportional to abundance

• Japanese longline data, 1975 – 2004– Provided by SPC

• Catch in numbers, effort in hooks• Methods

– 2005 – delta gamma GLM– 2003-2004 – neural networks– 1999-2002 – regression trees

Statistical methods

• Strata defined as 5º square / HBF category– Only strata with at least 5 non-zero catches are

included• Delta lognormal model

• w = g(Year.qtr, Lat.Long, HBF, effort)• f(y) = h(Year.qtr, Lat.Long, HBF)

, 0,Pr( )

(1 ) ( ) otherwisew y

Y yw f y

Change from last year

• In 2005– Used delta gamma model– Didn’t include effort in delta component of

GLM• Delta lognormal fit the data better (AIC)• Change makes very little difference to

results

Catch and effort (northern)

Northern fishery

0

5

10

15

20

25

30

35

1975 1980 1985 1990 1995 2000 2005Year

Cat

ch (t

hous

ands

)

0

20

40

60

80

100

120

140

Effo

rt (th

ousa

nds

of h

ooks

)

Yellowfin catchBigeye catchEffort (hooks)

Catch and effort (southern)

Southern fishery

0

50

100

150

200

250

300

1975 1980 1985 1990 1995 2000 2005Year

Cat

ch (t

hous

ands

)

0

100

200

300

400

500

600

Effo

rt (th

ousa

nds

of h

ooks

)

YellowfinBigeyeEffort (hooks)

Un-standardized data – proportion zero & nonzero CPUE

Yellowfin northern

0

0.2

0.4

0.6

0.8

1

1975 1980 1985 1990 1995 2000 2005

Year

Prop

ortio

n no

n-ze

ro

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

Non-

zero

cat

ch p

er u

nit e

ffor

tProportion nonzero Nonzero CPUE

Yellowfin southern

0.75

0.8

0.85

0.9

0.95

1

1975 1980 1985 1990 1995 2000 2005

Year

Prop

ortio

n no

n-ze

ro

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Non

-zer

o ca

tch

per u

nit e

ffor

t

Proportion nonzero Non-zero CPUE

Bigeye northern

0

0.2

0.4

0.6

0.8

1

1975 1980 1985 1990 1995 2000 2005

Year

Prop

ortio

n no

n-ze

ro

0

0.5

1

1.5

2

2.5

3

Non

-zer

o ca

tch

per u

nit e

ffor

t

Proportion nonzero Nonzero CPUE

Bigeye southern

0.75

0.8

0.85

0.9

0.95

1

1975 1980 1985 1990 1995 2000 2005

Year

Prop

ortio

n no

n-ze

ro

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

Non

-zer

o ca

tch

per u

nit e

ffor

t

Proportion nonzero Nonzero CPUE

Model selectionFishery Model Δ AICBET N yrqtr.latlong.hbf / lognormal 0

- hbf 118- latlong 6,080

BET S yrqtr.latlong.hbf / lognormal 0- hbf 817- latlong 13,575gamma 94,592

YFT N yrqtr.latlong.hbf / lognormal 0- hbf 30- latlong 1,237gamma 18,745

YFT S yrqtr.latlong.hbf / lognormal 0- hbf 336- latlong 32,936gamma 136,784

Residuals for non-zero component through time

1975 1980 1985 1990 1995 2000

-150

-100

-50

050

100

Northern bigeye

Time

Res

idua

ls

1975 1980 1985 1990 1995 2000 2005

-150

-100

-50

050

100

Northern yellowfin

Time

Res

idua

ls

1975 1980 1985 1990 1995 2000 2005

-200

-100

010

0

Southern bigeye

Time

Res

idua

ls

1975 1980 1985 1990 1995 2000 2005

-200

020

040

0

Southern yellowfin

Time

Res

idua

ls

Residuals for non-zero component

Southern bigeye

Residuals

Den

sity

-40 -20 0 20 40

0.00

0.02

0.04

0.06

0.08

Southern yellowfin

Residuals

Den

sity

-50 0 50

0.00

00.

005

0.01

00.

015

0.02

00.

025

0.03

0

Northern bigeye

Residuals

Den

sity

-40 -20 0 20 40

0.00

0.01

0.02

0.03

0.04

0.05

Northern yellowfin

Residuals

Den

sity

-60 -40 -20 0 20 40 60

0.00

0.01

0.02

0.03

Standardized CPUE - bigeye

Bigeye tuna

0

0.5

1

1.5

2

2.5

3

1975 1980 1985 1990 1995 2000 2005

Year

CP

UE

inde

x

Northern

Southern

Yellowfin tuna

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

1975 1980 1985 1990 1995 2000 2005

Year

CP

UE

inde

x

Northern

Southern

Standardized CPUE - yellowfin

Raw vs standardized CPUE

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1975 1980 1985 1990 1995 2000 20050

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

BET S raw

standardized

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

1975 1980 1985 1990 1995 2000 20050

0.5

1

1.5

2

2.5

3

3.5

YFT S raw

Standardized

Southern bigeye

y = -0.0051x + 11.126

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1975 1980 1985 1990 1995 2000 2005

Year

All f

acto

rs C

PUE

/ tim

e on

ly C

PUE

Standardized CPUE / CPUE standardized by time only

slope= -0.0051 ± 0.0006

Standardized CPUE / CPUE standardized by time only

Southern yellowfin

y = -0.0073x + 15.629

0

0.5

1

1.5

2

2.5

3

1975 1980 1985 1990 1995 2000 2005Year

All f

acto

rs C

PUE

/ tim

e on

ly C

PUE

slope = -0.007 ± 003

Average HBF through time

0

2

4

6

8

10

12

14

16

18

1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003

Year

Ave

rage

hoo

ks b

etw

een

float

s by

stra

tum

N

S

HBF parametersNorthern bigeye

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 2 4 6 8 10 12 14 16 18 20

Hooks between floats

Southern bigeye

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 2 4 6 8 10 12 14 16 18 20

Hooks between floats

Northern yellowfin

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 5 10 15 20 25

Hooks between floats

Southern yellowfin

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 5 10 15 20 25

Hooks between floats

Bigeye south12.5

7.5

2.5

-2.5

-7.5

-12.5

-17.5

-22.5

-27.5

-32.5

-37.5147.5 142.5 137.5 132.5 127.5 122.5 117.5 112.5 107.5 102.5 97.5 92.5 87.5 82.5 77.5 72.5

Lat

Long

2.25-2.5

2-2.25

1.75-2

1.5-1.75

1.25-1.5

1-1.25

0.75-1

0.5-0.75

0.25-0.5

0-0.25

Yellowfin south12.5

7.5

2.5

-2.5

-7.5

-12.5

-17.5

-22.5

-27.5

-32.5147.5 142.5 137.5 132.5 127.5 122.5 117.5 112.5 107.5 102.5 97.5 92.5 87.5 82.5 77.5 72.5

Lat

Long

3.5-4

3-3.5

2.5-3

2-2.5

1.5-2

1-1.5

0.5-1

0-0.5