Can We Have All Species Simultaneously at B MSY ? William Overholtz Jason Link Chris Legault Robert Gamble Michael Fogarty Laurel Col or ‘Having your Fish and Eating Them Too’
Mar 21, 2016
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