Atlantic Halibut (Hippoglossus hippoglossus

Atlantic Halibut (Atlantic Halibut (HippoglossusHippoglossus hippoglossushippoglossus))

Laurel ColLaurel ColNortheast Fisheries Science CenterNortheast Fisheries Science Center

Figure S1. Atlantic halibut landings from the Gulf of Maine- Georges Bank region during 1893-2006.

Year

1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Land

ings

(liv

e-w

eigh

t, m

t)

0

200

400

600

800

10004000

4500

5000

5500

6000

6500

70006,639 mt in 1879

Fall Survey Time Series

Spring Survey Time Series

Figure S2. Atlantic halibut US landings (mt) and discards (mt with 95% CI) from combined ratio estimation.

Year

1988 1990 1992 1994 1996 1998 2000 2002 2004 2006

US

Lan

ding

s an

d D

isca

rds

(mt)

0

20

40

60

80

100

120

140

160

180

200

Discards (mt) US Landings (mt)

Figure S3. Atlantic halibut biomass indices (stratified mean weight per tow and 5-year average) from NEFSC spring and autumn surveys.

Year

1965 1970 1975 1980 1985 1990 1995 2000 2005

Stra

tifie

d M

ean

Wei

ght (

kg) p

er T

ow

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Spring IndexAutumn Index

Total numbers of Atlantic halibut caught in NEFSC springand autumn surveys per year

Year

1965 1970 1975 1980 1985 1990 1995 2000 2005

Tota

l Num

ber o

f Hal

ibut

per

Yea

r

0

2

4

6

8

10

12

14

16

18

Spring SurveyAutumn Survey

Spring survey n=161# 0s in spring = 4

Autumn survey n=152#0s in autumn = 3

•• No age data availableNo age data available•• No door, vessel or gear conversions availableNo door, vessel or gear conversions available

Atlantic Halibut Current Status and ManagementAtlantic Halibut Current Status and Management

Current StatusCurrent Status• NEFSC: NEFSC: Overfished, Overfishing can not be determinedOverfished, Overfishing can not be determined

•• NOAA: NOAA: Species of ConcernSpecies of Concern

•• American Fisheries Society: American Fisheries Society: ThreatenedThreatened

•• IUCN: IUCN: EndangeredEndangered (due to overfishing)(due to overfishing)

ManagementManagement•• Northeast Multispecies Fishery Management Plan (Amendment 9) 1Northeast Multispecies Fishery Management Plan (Amendment 9) 1999999

•• 1 fish halibut possession limit1 fish halibut possession limit per trip for commercial and per trip for commercial and recreational vesselsrecreational vessels

•• Minimum size of 36 inchesMinimum size of 36 inches (91 cm)(91 cm)

Figure S2. Trends in swept-area biomass indices (mt) of Atlantic halibut from NEFSC autumn bottom trawl surveys.

Year

1965 1970 1975 1980 1985 1990 1995 2000 2005

Bio

mas

s (m

t)

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

5500

6000

5-Year Average Swept-Area Biomass

1/2 BMSY = 2700 mt

BMSY = 5400 mt

Year1965 1970 1975 1980 1985 1990 1995 2000 2005

Swep

t-Are

a Bi

omas

s (m

t)

0

100

200

300

400

500

600

700

Expl

oita

tion

Inde

x

0

1

2

3

4

5

Figure S4. Trends in Atlantic halibut commercial landings, fall stratified swept-area biomass, and exploitation index calculated as annual landings divided by the 5-year moving average of the swept-area biomass index.

Exploitation Index5-Year Average Swept-Area Biomass

Landings

20002000--2004 Experimental Halibut Fishery2004 Experimental Halibut Fishery

Maine DMR and Maine Sea GrantMaine DMR and Maine Sea Grant• Tagged 825 halibut in coastal Maine watersTagged 825 halibut in coastal Maine waters

•• 1,611 fish retained, 1,611 fish retained, otolithsotoliths and gonad samples takenand gonad samples taken

•• 92 recaptured as of Dec. 31, 2005 (11% return rate)92 recaptured as of Dec. 31, 2005 (11% return rate)

•• 28% of recaptures in Canadian waters28% of recaptures in Canadian waters

•• Mean days at large = 431Mean days at large = 431

•• Mean distance traveled = 151 km (1,758 km max)Mean distance traveled = 151 km (1,758 km max)

•• Mean length of tagged halibut = 79 cm (all immature)Mean length of tagged halibut = 79 cm (all immature)

Experimental Halibut FisheryExperimental Halibut Fishery

• Release area in greenRelease area in green•• Black dots represent recapture locationsBlack dots represent recapture locations

Basic Life History Characteristics for Atlantic HalibutBasic Life History Characteristics for Atlantic Halibut

Sigourney et. al. 2006Sigourney et. al. 2006•• Aged 530 Aged 530 otolithsotoliths from NMFS surveys and Experimental Halibut fisheryfrom NMFS surveys and Experimental Halibut fishery

•• Halibut up to ~40+ years oldHalibut up to ~40+ years old

•• LonglineLongline gear selected fish with faster growth compared to bottom trawlgear selected fish with faster growth compared to bottom trawl

•• A50 = 6.0 years for males, 7.3 years for femalesA50 = 6.0 years for males, 7.3 years for females

•• L50 = 80.2 cm for males, 103.0 cm for femalesL50 = 80.2 cm for males, 103.0 cm for females

Stock Reduction AnalysisStock Reduction Analysis

Kimura and Kimura and TagartTagart, 1982, 1982•• Uses available time series of catch data: Uses available time series of catch data: CCii (catch in year (catch in year ii))

•• For For ii = 1, = 1, ……, , nn catch equations:catch equations:CCii = = BBiiFFii(1 (1 -- exp(exp(-- FFii -- MM))/())/(FFii + + MM))BBii = = BBii--1 1 exp(exp(-- FFii--1 1 -- MM) + ) + RR for for ii>1>1

•• Provide starting estimates for: Provide starting estimates for: BB11 and and MM, solve for , solve for RR

•• Find best estimates of Find best estimates of FFii , , BBii

•• Two equations used for SRA plots:Two equations used for SRA plots:PP = = BBnn+1+1//BB11describes the decline in population biomass caused by describes the decline in population biomass caused by nn years of catchesyears of catches

•• Expected recruitment line (for varying values of Expected recruitment line (for varying values of RR and and BB11):):RR = = BB11(1 (1 –– exp(exp(-- MM))))


• MM = 0.006 (= 0.006 (--log(0.5)/max age 50)log(0.5)/max age 50)•• BBii = 11,000 = 11,000 mtmt (sum of 1893(sum of 1893--1897 landings)1897 landings)•• BBnn+1+1 = 252 = 252 mtmt (2007 swept(2007 swept--area biomass)area biomass)•• Gives Gives RR = 66 = 66 mtmt

Gulf of Maine Atlantic Halibutn=114 (1893-2006)

Initial Biomass (mt) 7000 8000 9000 10000 11000 12000 13000 14000 15000 16000

Rec

ruitm

ent B

iom

ass

(mt)

30

40

50

60

70

80

90

100

Expected Recruitment Line

P=0.018P=0.019

P=0.020

P=0.021

P=0.022

P=0.023

P=0.017


StrengthsStrengths•• Uses entire catch time seriesUses entire catch time series

•• Does not rely on surveys (little relation to catches and high uDoes not rely on surveys (little relation to catches and high uncertainty)ncertainty)

•• Very simplistic, no age data requiredVery simplistic, no age data required

•• Provide annual estimates of F (possibly use to determine overfiProvide annual estimates of F (possibly use to determine overfishing status)shing status)

•• Immigration or emigration do not violate assumptions of modelImmigration or emigration do not violate assumptions of model•• included in apparent recruitmentincluded in apparent recruitment

•• Plots can be used to verify results in relation to other indicePlots can be used to verify results in relation to other indices/known valuess/known values•• Compare to NMFS survey indices, future inshore Maine halibutCompare to NMFS survey indices, future inshore Maine halibutlonglinelongline surveys etc.surveys etc.


WeaknessesWeaknesses•• Not widely used for stock assessmentsNot widely used for stock assessments

•• Current regulations could skew catch in recent yearsCurrent regulations could skew catch in recent years•• Incorporate discards?Incorporate discards?

•• Starting estimates very rough for Starting estimates very rough for BBii, F, F11, , ……, F, Fnn, M, P, M, P

•• MM and and RR are fixed through timeare fixed through time•• RR can be variable in more complex versions of the modelcan be variable in more complex versions of the model

•• Current model assumes virgin biomass for Current model assumes virgin biomass for BBii•• might be possible include might be possible include FF in in initial biomassinitial biomass

•• Are assumptions/problems with this approach worse than the fallAre assumptions/problems with this approach worse than the fall--back?back?•• Any better alternatives?Any better alternatives?

Atlantic Halibut Biomass from Stock Reduction AnalysisBi = 7000 mt

Years

1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Biom

ass

or L

andi

ngs

(mt)

0

2000

4000

6000

8000

SRA Biomass

1/2 BMSY = 2700 mt

BMSY = 5400 mt

Landings (mt)


Years

1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Biom

ass

or L

andi

ngs

(mt)

0

2000

4000

6000

8000

10000

12000

14000

16000

Biomass (SRA, Bi=15000mt)

1/2 BMSY = 2700 mt

BMSY = 5400 mt

Landings (mt)


Years

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Biom

ass

or L

andi

ngs

(mt)

0

500

1000

1500

2000

2500

3000

SRA Biomass

1/2 BMSY = 2700 mt

Landings (mt)

Fall 5-year Swept-Area Biomass


Years

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Biom

ass

or L

andi

ngs

(mt)

0

500

1000

1500

2000

2500

3000

SRA Biomass

1/2 BMSY = 2700 mt

Landings (mt)Fall 5-year Swept-Area Biomass


Years

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Biom

ass

or L

andi

ngs

(mt)

0

500

1000

1500

2000

2500

3000

SRA Biomass

1/2 BMSY = 2700 mt

Landings (mt)

Fall 5-year Swept-Area Biomass

Atlantic Halibut Fishing Mortality from Stock Reduction AnalysisBi = 7000 mt

Year

1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Land

ings

(liv

e-w

eigh

t, m

t)

0

1000

2000

3000

4000

5000

6000

Stoc

k R

educ

tion

Anal

ysis

F

0

1

2

3

4

5

6

Atlantic Halibut Fishing Mortality from Stock Reduction AnalysisBi = 15000 mt

Year

1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Land

ings

(liv

e-w

eigh

t, m

t)

0

1000

2000

3000

4000

5000

6000

Stoc

k R

educ

tion

Anal

ysis

F

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

Atlantic Halibut Landings

Year

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Hal

ibut

Lan

ding

s (m

t)

0

50

100

150

200

250

300

350

400

CanadaUSOther

Atlantic halibut NEFSC autumn biomass indices (stratified mean weight per tow) with 1 standard error

Year

1965 1970 1975 1980 1985 1990 1995 2000 2005

Stra

tifie

d M

ean

Wei

ght (

kg) p

er T

ow

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Atlantic halibut NEFSC spring biomass indices (stratified mean weight per tow) with 1 standard error

Year

1965 1970 1975 1980 1985 1990 1995 2000 2005

Stra

tifie

d M

ean

Wei

ght (

kg) p

er T

ow

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Figure S3. Atlantic halibut biomass indices (stratified mean weight per tow) from NEFSC spring and autumn surveys.

Year

1965 1970 1975 1980 1985 1990 1995 2000 2005

Stra

tifie

d M

ean

Wei

ght p

er T

ow

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7


Use of Spring v. Autumn Survey IndexUse of Spring v. Autumn Survey Index

Time SeriesTime Series• Autumn survey has longer time seriesAutumn survey has longer time series•• Autumn survey includes relatively high landings during 1963Autumn survey includes relatively high landings during 1963--1967 1967 (highest landings since 1930s)(highest landings since 1930s)

VariabilityVariability•• CVs/SE similar between surveysCVs/SE similar between surveys•• Similar number of years with 0 halibutSimilar number of years with 0 halibut•• Similar number of total halibut caughtSimilar number of total halibut caught

Temperature Correlation in Spring SurveyTemperature Correlation in Spring Survey•• Spring sweptSpring swept--area biomass neg. corr. with spring bottom waterarea biomass neg. corr. with spring bottom watertemperature anomaliestemperature anomalies

•• Water temp. influences spring distributionWater temp. influences spring distribution--Not seen in autumn surveyNot seen in autumn survey

Atlantic Halibut NEFSC Spring and Autumn Survey Indices and Swept-Area Biomass

Year

1965 1970 1975 1980 1985 1990 1995 2000 2005

Stra

tifie

d M

ean

Wei

ght p

er T

ow

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

5-Ye

ar A

vera

ge S

wep

t-Are

a B

iom

ass

(mt)

0

200

400

600

800

1000

1200

1400


Discarded Halibut Kept HalibutYear Mean Length (cm) Std Err N Year Mean Length (cm) Std Err N1990 . . . 1990 46.6 2.0012 61991 . . . 1991 92.0 . 11992 33.0 . 1 1992 67.1 5.2457 111993 31.3 13.3458 3 1993 62.8 5.5333 101994 42.4 5.1049 5 1994 73.3 5.0781 161995 27.2 5.4858 6 1995 79.6 4.6356 291996 . . . 1996 69.2 10.027 51997 36.3 2.1858 3 1997 67.5 11.3893 61998 . . . 1998 . . . 1999 62.0 . 1 1999* . . . 2000 57.0 4.0778 13 2000 . . . 2001 67.5 2.9518 13 2001 118.0 6 22002 70.2 4.7648 13 2002 88.0 9.0738 62003 64.0 1.6363 91 2003 81.0 5.349 292004 57.1 1.3502 87 2004 83.9 3.9709 332005 60.4 1.3042 160 2005 76.4 2.5691 802006 63.0 1.495 107 2006 84.9 3.5611 372007 64.0 2.0581 70 2007 89.4 4.7544 29

*Minimum size of 91cm implemented in 1999

NMFS Fall Survey Halibut in Massachusetts Inshore Strata

Year

1980 1985 1990 1995 2000 2005

Stra

tifie

d M

ean

Wei

ght p

er T

ow (k

g)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

Sw

ept A

rea

Bio

mas

s (m

t)

0

5

10

15

20

25

30

5-Year Average Swept Area Biomass

NMFS Spring Survey Halibut in Massachusetts Inshore Strata

Year

1980 1985 1990 1995 2000 2005

Stra

tifie

d M

ean

Wei

ght p

er T

ow (k

g)

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

Sw

ept A

rea

Bio

mas

s (m

t)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8


NMFS Fall Survey Scotian Shelf Halibut

Year

1965 1970 1975 1980 1985 1990 1995 2000 2005

Stra

tifie

d M

ean

Wei

ght p

er T

ow (k

g)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Sw

ept A

rea

Bio

mas

s (m

t)

0

200

400

600

800


NMFS Spring Survey Scotian Shelf Halibut

Year

1970 1975 1980 1985 1990 1995 2000 2005

Stra

tifie

d M

ean

Wei

ght p

er T

ow (k

g)

0

1

2

3

4

5

6

Sw

ept A

rea

Bio

mas

s (m

t)

0

200

400

600

800

1000

1200

1400

1600


Halibut von Bertalanffy Growth CurvePooled Data Females

Age

0 5 10 15 20 25 30

Leng

th (c

m)

0

50

100

150

200

250

Halibut von Bertalanffy Growth CurvePooled Data Males

Age

0 5 10 15 20 25 30

Leng

th (c

m)

0

50

100

150

200

Halibut Yield per RecruitFemale Pooled

F

0.0 0.5 1.0 1.5 2.0

YPR

0

2e+4

4e+4

6e+4

8e+4

1e+5

FMAX = 0.0354

F0.1 = 0.0227

Halibut Spawning Stock Biomass per RecruitFemale Pooled

F

0.0 0.5 1.0 1.5 2.0

SS

B/R

ecru

it

0

2e+6

4e+6

6e+6

8e+6

1e+7

F40 = 0.0238

Atlantic Halibut (Hippoglossus hippoglossus

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