7/30/2019 PowerPoint Presentation by Anna Olafsdottir of Memoral University, St. John's Nfld.

1/17

AnnaOlafsdo+r

GeorgeRoseCentreforFisheries

EcosystemResearch,

MemorialUniversity

Preparedfor:

ArccFisheryAlliance

OceansNorthCanada

TheGreenlandhalibutfisheryinNAFOSubarea0from1996

to2011

7/30/2019 PowerPoint Presentation by Anna Olafsdottir of Memoral University, St. John's Nfld.

2/17

GreenlandhalibutmostvaluableCanadiangroundfish

speciesinNWAtlanc

7/30/2019 PowerPoint Presentation by Anna Olafsdottir of Memoral University, St. John's Nfld.

3/17

OutlineTotalAllowableCatch(TAC)hasdoubleinthelast

decadedespiteminimalbiologicalknowledgeonstock

Analysis:

catchlengthfrequencydatafishsizebygeartypeyield-per-lengthnumberofindividualfishforatoncaught

Recommendaons:morereserachneededslot-lengthapproachtoharvesngshouldbeconsidered,reducingfishingoflength80cm

SmallFishProtocol(

7/30/2019 PowerPoint Presentation by Anna Olafsdottir of Memoral University, St. John's Nfld.

4/17

LimitedknowledgeonbiologyofGreenlandhalibutin0A

and0B

Background:biology

Age

Growthrate

Sizeatmaturity

Spawningstockbiomass

Fishingmortality

?Yield-per-recruit

Biologicalreferencepoints

Fishingsustainability

RiskassessmentoncurrentTACX

7/30/2019 PowerPoint Presentation by Anna Olafsdottir of Memoral University, St. John's Nfld.

5/17

TACandcatchinSubarea0doubledbetween2000and2011

Background:fishery

7/30/2019 PowerPoint Presentation by Anna Olafsdottir of Memoral University, St. John's Nfld.

6/17

Availablecatchlengthfrequencydatafromthefishery

Analysis:at-seaobserverdata

7/30/2019 PowerPoint Presentation by Anna Olafsdottir of Memoral University, St. John's Nfld.

7/17

In0Atrawl:lengthoffishhasdeclinedsince2006

Analysis:lengthfrequency

7/30/2019 PowerPoint Presentation by Anna Olafsdottir of Memoral University, St. John's Nfld.

8/17

In0Btrawl:lengthoffishhasincreasedsince2006

Analysis:lengthfrequency

7/30/2019 PowerPoint Presentation by Anna Olafsdottir of Memoral University, St. John's Nfld.

9/17

Gillnets:limitedchangesinfishlengthsincefisherybegan

Analysis:lengthfrequency

7/30/2019 PowerPoint Presentation by Anna Olafsdottir of Memoral University, St. John's Nfld.

10/17

TrawlsoenviolateSmallFishProtocol(max15%

7/30/2019 PowerPoint Presentation by Anna Olafsdottir of Memoral University, St. John's Nfld.

11/17

Gillnetscatchlargerfishthandotrawls

Analysis:fishlength

7/30/2019 PowerPoint Presentation by Anna Olafsdottir of Memoral University, St. John's Nfld.

12/17

Sustainablefisheryis

balancingbirthanddeath

Yield-per-lengthmodels:

1)calculateyieldperindividual

assumingspecificfishing

mortality

2)esmateatwhatlength

fishingshouldstartfor

maximumyield

stockbiomass

growthreproducon

fishingmortality

naturalmortalityX

fisheriesscience

Yieldcanbeesmated

7/30/2019 PowerPoint Presentation by Anna Olafsdottir of Memoral University, St. John's Nfld.

13/17

Gillnetsulizefishgrowthpotenalbeerbycatching

largerfish

Analysis:yield-per-length

F=fishingmortalityZ=totalmortality

7/30/2019 PowerPoint Presentation by Anna Olafsdottir of Memoral University, St. John's Nfld.

14/17

Fishingmortalityaffectsyield-per-length

Analysis:yield-per-length

F=fishingmortality

Z=totalmortality

7/30/2019 PowerPoint Presentation by Anna Olafsdottir of Memoral University, St. John's Nfld.

15/17

Trawlscatchtwiceasmanynumberoffishforatoncaught

thandogillnets

Analysis:numberperton

7/30/2019 PowerPoint Presentation by Anna Olafsdottir of Memoral University, St. John's Nfld.

16/17

Annuallytrawlscatch3-4millionfishandgillnets1-1.5

millioninDivision0A

Analysis:numberperton

7/30/2019 PowerPoint Presentation by Anna Olafsdottir of Memoral University, St. John's Nfld.

17/17

Summary:applyprecauonaryapproachunlmore

biologicalinformaononstockareavailable

All13years

Conclusions: 1)Researchneededtoestablishsustainabilityoffisheryand

biologicalreferencepoints

2)Smallversuslargefish?Immatureversusmaturefish?

Recommendaons:1)moreresearch

2)considerslot-lengthapproachtoharvesng,reducing

fishingoflenght80cm

3)enforcethesmallfishprotocol(