.

Assessment of the Icelandic cod stock

Björn Ævarr SteinarssonMarine Research Institute

Components of adviceComponents of advice(short-term)(short-term)

Data Data analysis Assess. Prediction

Landings

Lengthmeas.

Otoliths

Surveys

Catch innumbers

Indices

Stockassessment

Predicteddevelopm.

of stockand catchLogbooks

CPUE

OtolithsLength m.

Input data

• Catch in numbers by age groups

• Survey indices

• Catch per unit effort (CPUE) from the fleet

Icelandic cod. Landings1906-1996

0

100

200

300

400

500

600

1905 1915 1925 1935 1945 1955 1965 1975 1985 1995

Year

'000

t

Other NationsIceland

CodLandings by gear

0102030405060708090

100

Bottomtrawl

Gillnet Longline Handline Danishseine

%

Distribution of cod catches

Distribution of cod catches

Sampling from landingsSampling from landings

• Allocation

– Samples alloced proportional to landings in each fleet category - Real time.

• Implementation

– MRI staff

– Inspectors from the Fisheries Directorate

– The Coast Guard

• Magnitude

– Annually about 150.000 length measurements and 15000 otoliths for ageing.

CodCatch in number by age groups

05

10152025303540

3 4 5 6 7 8 9 10+

Age

Num

bers

in m

illio

ns

CV 20

Icelandic Groundfish SurveyIGFS

• Annually about 600 fixed trawl stations taken in March all

around Iceland since 1985.

• Performed by 4-5 identical trawlers

• Standarized trawl, trawling distance, trawling speed etc.

• About 50 000 length measured and 5 000 otoliths taken for

ageing

• Gutted and ungutted weight, liver weight, gonad weight,

stomach content anlysis, maturity etc.

IGFS Towing station in spring survey

IGFS- Primary objectives -

• Independent estimate of relative

abundance.

• Annual indices of recruitment.• Various biological parameters.

IGFSTotal biomass index

0

100

200

300

400

500

600

85 90 95 2000Year

Bio

mas

s In

dex

CV 10-16

IGFSRelative abundance index by age groups in 2002

0

10

20

30

40

50

1 2 3 4 5 6 7 8 9 10 11 12

Age groups

Inde

x in

Num

bers

Survey abundance vs number alive in the sea

Number of fish of age a in surveyNu

mb

er o

f fi

sh o

f ag

e a

in t

he

sea

aa qUN

IGFS - COD

Index of 3 years old vs. 4 years old a year later

82

83

84

85

86

8788

8990

91

92

93

94

95

96

97

R2 = 0.8995

0

20

40

60

80

100

120

0 20 40 60 80 100 120

Index of age group 3

Ind

ex

of

age

4 a

ye

ar la

ter

LogbooksExample

Distribution of Logbooks records

Bottom trawl

Shrimp trawl

Longline

Capelin herring

Dragnót

Pelagic trawl

Herring

LogbooksObjectives

• Collecting data to estimate CPUE/Effort

• Behavior of the fishing fleet

• Relationship with fishermen

CPUE vs Biomass

CPUE (tonn/hour)

Bio

mas

s (t

on

nes

) qCPUEB

CODCPUE 1991-2001 by gears

60

80

100

120

140

160

180

91 92 93 94 95 96 97 98 99 2000 2001Year

CP

UE

in

dex

Bottom trawl Gillnet Longline

Distribution of cod catches

Greenland HalibutMain fishing areas

CODCatch in numbers 1991-2000 (Millions)

Yearclass 1988Yearclass 1988

Ár/Aldur 3 4 5 6 7 8 9 10 11 12 13 141991 8.55 25.13 15.49 21.51 25.04 6.36 0.90 0.24 0.13 0.06 0.01 0.011992 12.22 21.71 26.52 11.41 10.07 8.30 2.01 0.26 0.05 0.03 0.01 0.011993 20.50 33.08 15.20 13.28 3.58 2.79 2.71 1.18 0.18 0.03 0.01 0.011994 6.16 24.14 19.67 6.97 4.39 1.26 0.60 0.51 0.28 0.05 0.02 0.011995 10.77 9.10 16.83 13.07 4.12 1.60 0.31 0.18 0.16 0.14 0.03 0.011996 5.36 14.89 7.37 12.31 9.43 2.16 0.84 0.21 0.08 0.07 0.06 0.011997 1.72 16.44 17.30 6.71 7.38 5.96 1.15 0.49 0.13 0.03 0.04 0.021998 3.55 7.71 25.39 20.17 5.89 3.86 2.95 0.50 0.20 0.06 0.03 0.011999 2.53 19.55 15.23 24.62 12.97 2.80 1.49 0.75 0.14 0.05 0.01 0.012000 10.47 6.56 29.00 11.20 11.36 5.70 1.10 0.57 0.31 0.07 0.02 0.01

CODIGFS index vs. VPA estimate of age group 6

97

96

95

9493

92

91

90

89

8887

86

85

R2 = 0.8513

0

20

40

60

80

100

120

0 20 40 60 80 100 120IGFS-Index

VP

A

0

200

400

600

800

1000

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002Year

Th

ou

s. t

on

ne

s

XSA TSA

EX-CAM AD-CAM

Coleraine ADAPT

BORMICON

COD COD Estimated 4+ biomass by different assessment models.Estimated 4+ biomass by different assessment models.

CODProbability plots of estimated fishable biomass in 2002-2005

0.0

0.2

0.4

0.6

0.8

1.02002 2003

0.0

0.2

0.4

0.6

0.8

1.0

600 800 1000 1200

2004

600 800 1000 1200

2005

1000 tonnes