Can We Have All Species Simultaneously at BMSY ?

William OverholtzJason Link

Chris LegaultRobert GambleMichael Fogarty

Laurel Col

or ‘Having your Fish and Eating Them Too’

GARM Ecosystem Terms of Reference

Provide analyses to determine if the Northeast Shelf LME (Large Marine Ecosystem) can support the reference point biomasses (summed BRPs) required for the GARM species as well as the other demersal and pelagic fish resources in the region.

ICNAF Two Tier System-Determine total system MSY:

MS MSY 980,000 MT-Allocate catches for each species accounting for by- catch and making sure the total doesn’t exceed system MSY

SS MSY 1,300,00 MT

Motivation: Earlier AnalysesSuggested System is Energy Limited

Energy Constraints?

Earlier Energy Budgets for Georges Bank indicated Production Is “Tightly Bound” with Most Fish Production

Consumed by Other Fish (Cohen et al. 1982; Sissenwine et al. 1984)

NAFO Div. 5 and 6 Landings

1960 1970 1980 1990 2000

Year

0

500

1000

1500

2000

2500

Lan d

ing s

( '00

0 M

T )

Principal Groundfish Other Finfish Small PelagicsMedium/Large Pelagics Elasmobranchs CrustaceansMolluscs Other Inverts

ICNAF Fish MSY Level

Approach:Determine Combined BMSY and/or MSY Levels for all

Fish Species based on Single Species Analyses Compare with other Temperate Systems

Revisit Brown et al. (1976) Develop Aggregate Surplus Production Models

(ASPIC, ASP Models)Energy Budget Models

Shelfwide Ecopath and EcoNetWrk Models Based on EMAX Analyses

Estimate Fishery Production Potential and Primary Production Required to Sustain Fisheries

Multispecies Production Model Simulations

Determine Combined BMSY and/or MSY Levels based on Single Species Analyses

EmpiricalSummarize current information on the BRPs

for GARM species and other fish components of the US Northeast Shelf LME.

Express results on a unit area basis (t/km2)Compare to historic analyses, recent

analyses, (mass balance models), current biomass, and biomass in other systems.

Aggregate BMSY and MSY Levelsfor Species Groups based on Single Species Analysis

Species Group

MSY (kt) t km-2 BMSY(kt) t km-2

GARM Species

196.68 0.79 1,424.79 5.78

Pelagics 254.18 1.44 1,295.98 5.25

Elasmobranchs

17.79 0.72 1,155.73 4.69

Total Biomass and Density Estimates by Species Group

Species Group

Biomass (kt)

t km-2

Garm Species 1,424.79 5.78

Elasmobranchs

1,155.73 4.69

Demersal Omnivores

15.30 0.06

Demersal Piscivores

252.90 1.07

Demersal Benthivores

850.57 3.45

Medium Pelagics

256.68 1.04

Total 3,965.96 16.079

Develop Aggregate Surplus Production ModelsAssemble time-series of survey indices,

landings, biomass.Use ASPIC and other multi-species surplus

production models to estimate aggregate BRPs.Fit variations of SP=Bt-1-Bt+CFit Schaefer and Pella-Tomlinson models

(Mueter and Megrey 2007)Add environmental covariatesCompare to summed single species results by

group and total

GARM Species Relative Abundance(Spring)

ATLANTIC COD HADDOCK POLLOCK

WHITE HAKE ATLANTIC HALIBUT AMERICAN PLAICE

YELLOWTAIL FLOUNDER WINTER FLOUNDER WITCH FLOUNDER

WINDOWPANE ACADIAN REDFISH OCEAN POUT

0.000

10.000

20.000

30.000

40.000

50.000

60.000

70.000

80.000

90.000W

eigh

t (K

g) p

er T

ow

1968 1971 1974 1977 1980 1983 1986 1989 1992 1995 1998 2001 2004Year

GARM Species Spring Stratified Mean Weight per Tow

GARM Species Relative Abundance(Autumn)

ATLANTIC COD HADDOCK POLLOCK

WHITE HAKE ATLANTIC HALIBUT AMERICAN PLAICE

YELLOWTAIL FLOUNDER WINTER FLOUNDER WITCH FLOUNDER

WINDOWPANE ACADIAN REDFISH OCEAN POUT

0.000

20.000

40.000

60.000

80.000

100.000

120.000 Wei

ght (

Kg)

per

Tow

1964 1968 1972 1976 1980 1984 1988 1992 1996 2000 2004Year

Stratified Mean Weight per Tow

Energy Budget Calculations

J. Link, B. Overholtz, C. Legault, L. Col, M. Fogarty Pelagic

Fisheries

Larval & Juvenile Fish

Sea birds

Pelagic Sharks

Baleen whales

Odontocetes

MediumPelagics

DemersalsPiscivoresSquid

Small Pelagics Anadromous

Small Pelagics Commercial

Micronekton

Small Copepods

Discards

Primary Producers

Gelatinous Zooplankton

Large Copepods

Meso-pelagics

ShrimpMegaBenthosFilterers

Demersal Fisheries

Large Pelagics Pinnipeds Coastal

Sharks

DemersalBenthivores

DemersalsOmnivores

Small Pelagics Other

Polychaetes

MacroBenthosOther

Detritus-POC

Bacteria

MacroBenthosCrustaceans

MegaBenthosOther

MacroBenthosMolluscs

Energy Budget ApproachUsing EMAX balanced budgets for 4 Combined regions (MAB, SNE, GB, GM) Areally weighted for B, P/B, C/B Common diet with all nodes used from SNESummed for fisheries and bycatchUsed mass-balance eqns:

iiii ERPC Where C is consumption, P is production, R is respiration, and E is Excretion

Ecopath Formulation

ii

jij

jjiii

ii CEMDC

BCBBAIMEE

BPB

***

Where B is biomass, EE is Ecotrophic Efficiency, IM is Immigration, BA is Biomass Accumulation, P/B is the Production to Biomass Ratio, C/B is the Consumption to Biomass Ratio, DC is the Diet Composition, EM is emigration, and C is catch

Indexed by species (I,j)

Estimate Fishery Production Potential and Primary Production Required to Sustain Fisheries

FP = R {M} PP TE(TL-1)

Where FP is FisheryProduction Potential, R is a Retention RatePP is Primary ProductionM is the fraction of PPAvailable to HigherTrophic levels, TE is TransferEfficiency and TL is the MeanTrophic Level

Primary Production

Primary Production based onSatellite-Derived Estimates

Trophic Position of Individual Species

BluefishGoosefishSea Raven

White HakeWindowpaneYellowtail FlFourspot Fl

CodLonghorn Sculpin

Winter SkatePollock

Red HakeHaddockWitch Fl

Little SkateSIlver Hake

Atlantic HerringSpiny Dogfish

Winter FlSquid

ButterfishOcean PoutSand Lance

Scallop

0 1 2 3 4 5Trophic Level

15 N Trophic Level

Mean Trophic Level of Landings Relatively Constant

1960 1970 1980 1990

Year

0

0.5

1

1.5

2

2.5

3

3.5

Mea

n T r

ophi

c Le

vel o

f Lan

d ing

s

Results Sensitive to Transfer Efficiencies

2.5 3 3.5 4 4.5

Trophic Level

0

500

1000

1500

2000

2500

3000

3500

PPR

Mu l

tiplie

r 15%

12.5%

10%

Transfer Efficiency

MS & Aggregate Production Model Simulator

dNdt

r NN N

K T

N

K KN H Ni

i i

i ig g

g

g

iG G

G

gip p

p

i i

(

( ) ( )) ( )1 1 1

1

biomassNrategrowth r

capacity carryingK

tcoefficienn competitiotcoefficienpredation

rateharvest H

speciesi) species(on predator ip

member guildgguildG

Model DetailsProgrammed in Visual C#Uses 5th order Runge-Kutta iterative numerical

solutionsUser friendly GUI developedNot an estimator or fitting toolModel description variously in print, in review,

etc.

Model Parameterization

Set species, assign to guilds/groups

Determine system and guild carrying capacities, based on BMSY’sSystem = 4.0 million mt Groundfish = 1.42 million mtPelagics = 1.29 million mtElasmobranchs = 1.15 million mt

Single Species Dynamics

No Interspecific Interactions

Individual Species with Interactions

Aggregate Species Dynamics

GARM Ecosystem TOR Status

Compilation of MSY and BMSY Estimates CompletePreliminary Shelf-wide Network Model Available and

Experimental Scenarios InitiatedInitial ASPIC Runs Completed for Aggregate BiomassPreliminary Estimates of Fishery Production Potential

and PPR CompletedSensitivity Analysis of FPP and PPR underway for Transfer

EfficienciesMultispecies Production Model Simulator Implemented.Preliminary Simulator Scenario Results Completed

Additional Material

Energy Budget Preliminary Results

Final Balanced BMSY Scenario

-250%

-200%

-150%

-100%

-50%

0%

50%

100%

150%S

mal

l Pel

agic

s- c

omm

erci

al

Sm

all P

elag

ics-

oth

er

Sm

all P

elag

ics-

squ

id

Sm

all P

elag

ics-

ana

drom

ous

Med

ium

Pel

agic

s- (p

isci

vore

s&

oth

er)

Dem

ersa

ls- b

enth

ivor

es

Dem

ersa

ls- o

mni

vore

s

Dem

ersa

ls- p

isci

vore

s

%

Diff from input

Diff from baseline

Preliminary Energy Budget Conclusions

Rebalancing relative to input levels suggests may not be able to have all fish species at BMSY due to flow constraints

All scenarios were balanced largely predicated upon a higher small pelagic-commercial biomass and a lower demersal-omnivore and piscivore biomass

ASPIC Estimates (kt)

Target Estimates (kt)

Species Group MSY BMSY(kt) MSY BMSY(kt)

GARM 126 758 197 1,424Pelagic 422 2,971 354 1,295Elasmobranch 59 1,895 18 1,156Garm & Pelagic 422 5,971 551 2,719GARM & Pelagic & Elasmobranch

579 5,350 569 3,875

Preliminary Aggregate BRP Estimates