This case study is based on the 2011 and 2017 stock assessments. The operating model is conditioned on the stock in 1989, and is intended to investigate the impact of the observed change in growth pattern that occurred after this time.
This base-case OM projects the population forward from 1989 and assumes that growth does not change - i.e it is conditioned on the knowledge of growth pattern at that time.
Two alternative robustness OMs are:
Growth in future projections changes to that observed after 1990 (Figure 14 in 2011 Assessment).
The change in growth in future projections is half of that observed after 1990.
The OM rdata file can be downloaded from here
Download and import into R using myOM <- readRDS('OM.rdata')
Species: Merluccius productus
Common Name: Pacific Hake
Management Agency: Joint US-Canada Hake
Region: North-East Pacific
OM Name: Name of the operating model: Pacific_Hake
nsim: The number of simulations: 192
proyears: The number of projected years: 50
interval: The assessment interval - how often would you like to update the management system? 4
pstar: The percentile of the sample of the management recommendation for each method: 0.5
maxF: Maximum instantaneous fishing mortality rate that may be simulated for any given age class: 0.8
reps: Number of samples of the management recommendation for each method. Note that when this is set to 1, the mean value of the data inputs is used. 1
Source: A reference to a website or article from which parameters were taken to define the operating model
2011 and 2017 stock assessments
maxage: The maximum age of individuals that is simulated (there is no plus group ). Single value. Positive integer
Specified Value(s): 22
Based on the maximum observed age.
R0: The magnitude of unfished recruitment. Single value. Positive real number
Specified Value(s): 10000
Scaling parameter set at an arbitrary value
M: Natural mortality rate. Uniform distribution lower and upper bounds. Positive real number
Specified Value(s): 0.22, 0.22
Fix at the MLE from 2017 assessment.
M2: (Optional) Natural mortality rate at age. Vector of length maxage . Positive real number
Slot not used.
Mexp: Exponent of the Lorenzen function assuming an inverse relationship between M and weight. Uniform distribution lower and upper bounds. Real numbers <= 0.
Specified Value(s): 0, 0
No justification provided.
Msd: Inter-annual variability in natural mortality rate expressed as a coefficient of variation. Uniform distribution lower and upper bounds. Non-negative real numbers
Specified Value(s): 0.05, 0.1
A small amount of inter-annual variability in M was assumed.
Histograms of 48 simulations of M
, Mexp
, and Msd
parameters, with vertical colored lines indicating 3 randomly drawn values used in other plots:
The average natural mortality rate by year for adult fish for 3 simulations. The vertical dashed line indicates the end of the historical period:
Natural mortality-at-age for 3 simulations in the first historical year, the last historical year (i.e., current year), and the last projected year:
Natural mortality-at-length for 3 simulations in the first historical year, the last historical year (i.e., current year), and the last projected year:
h: Steepness of the stock recruit relationship. Uniform distribution lower and upper bounds. Values from 1/5 to 1
Specified Value(s): 0.86, 0.86
Fixed at the MLE in the 2017 assessment.
SRrel: Type of stock-recruit relationship. Single value, switch (1) Beverton-Holt (2) Ricker. Integer
Specified Value(s): 1
A Beverton-Holt SRR was used based on the 2017 assessment.
Perr: Process error, the CV of lognormal recruitment deviations. Uniform distribution lower and upper bounds. Non-negative real numbers
Specified Value(s): 0.8, 1.3
Based on the 2017 assessment.
AC: Autocorrelation in recruitment deviations rec(t)=ACrec(t-1)+(1-AC)sigma(t). Uniform distribution lower and upper bounds. Non-negative real numbers
Specified Value(s): 0, 0.1
Based on the 2017 assessment.
Histograms of 48 simulations of steepness (h
), recruitment process error (Perr
) and auto-correlation (AC
) for the Beverton-Holt stock-recruitment relationship, with vertical colored lines indicating 3 randomly drawn values used in other plots:
Period: (Optional) Period for cyclical recruitment pattern in years. Uniform distribution lower and upper bounds. Non-negative real numbers
Slot not used.
Amplitude: (Optional) Amplitude in deviation from long-term average recruitment during recruitment cycle (eg a range from 0 to 1 means recruitment decreases or increases by up to 100% each cycle). Uniform distribution lower and upper bounds. 0 < Amplitude < 1
Slot not used.
Linf: Maximum length. Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 80, 80
The estimated von Bertalanffy growth parameters for female fish from the 1975 - 1990 period were used for the base-case model (Figure 14 in the 2011 asssement).
K: von Bertalanffy growth parameter k. Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 0.08, 0.08
See Linf
t0: von Bertalanffy theoretical age at length zero. Uniform distribution lower and upper bounds. Non-positive real numbers
Specified Value(s): -6, -6
Estimated from the mean length-at-age curves reported in Figure 7 of the 2011 assessment.
LenCV: Coefficient of variation of length-at-age (assumed constant for all age classes). Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 0.1, 0.15
Default values for variability in length-at-age were assumed.
Ksd: Inter-annual variability in growth parameter k expressed as coefficient of variation. Uniform distribution lower and upper bounds. Non-negative real numbers
Specified Value(s): 0, 0.02
A small amount of inter-annual variability in K was assumed.
Linfsd: Inter-annual variability in maximum length expressed as a coefficient of variation. Uniform distribution lower and upper bounds. Non-negative real numbers
Specified Value(s): 0, 0.02
A small amount of inter-annual variability in Linf was assumed.
Histograms of 48 simulations of von Bertalanffy growth parameters Linf
, K
, and t0
, and inter-annual variability in Linf and K (Linfsd
and Ksd
), with vertical colored lines indicating 3 randomly drawn values used in other plots:
The Linf and K parameters in each year for 3 simulations. The vertical dashed line indicates the end of the historical period:
Sampled length-at-age curves for 3 simulations in the first historical year, the last historical year, and the last projection year.
L50: Length at 50 percent maturity. Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 36, 36
From the 2017 assessment.
L50_95: Length increment from 50 percent to 95 percent maturity. Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 4, 4
From the 2017 assessment.
Histograms of 48 simulations of L50
(length at 50% maturity), L95
(length at 95% maturity), and corresponding derived age at maturity parameters (A50
and A95
), with vertical colored lines indicating 3 randomly drawn values used in other plots:
Maturity-at-age and -length for 3 simulations in the first historical year, the last historical year (i.e., current year), and the last projected year:
D: Current level of stock depletion SSB(current)/SSB(unfished). Uniform distribution lower and upper bounds. Fraction
Specified Value(s): 0.9, 1.1
From the 2017 assessment. The stock in 1989 was estimated to be at high levels.
Fdisc: Fraction of discarded fish that die. Uniform distribution lower and upper bounds. Non-negative real numbers
Specified Value(s): 0.05, 0.15
A small degree of discard mortality was assumed, although the model has little discarding.
Histograms of 48 simulations of depletion (spawning biomass in the last historical year over average unfished spawning biomass; D
) and the fraction of discarded fish that are killed by fishing mortality (Fdisc
), with vertical colored lines indicating 3 randomly drawn values.
a: Length-weight parameter alpha. Single value. Positive real number
Specified Value(s): 0
From the 2017 assessment.
b: Length-weight parameter beta. Single value. Positive real number
Specified Value(s): 2.96
From the 2017 assessment.
Size_area_1: The size of area 1 relative to area 2. Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 0.5, 0.5
A mixed stock is assumed
Frac_area_1: The fraction of the unfished biomass in stock 1. Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 0.5, 0.5
A mixed stock is assumed.
Prob_staying: The probability of inviduals in area 1 remaining in area 1 over the course of one year. Uniform distribution lower and upper bounds. Positive fraction.
Specified Value(s): 0.5, 0.5
A mixed stock is assumed
Histograms of 48 simulations of size of area 1 (Size_area_1
), fraction of unfished biomass in area 1 (Frac_area_1
), and the probability of staying in area 1 in a year (Frac_area_1
), with vertical colored lines indicating 3 randomly drawn values used in other plots:
nyears: The number of years for the historical spool-up simulation. Single value. Positive integer
Specified Value(s): 24
Based on the assumption the fishery began in 1966 and the OM is based on 1989.
Spat_targ: Distribution of fishing in relation to spatial biomass: fishing distribution is proportional to B^Spat_targ. Uniform distribution lower and upper bounds. Real numbers
Specified Value(s): 1, 1
Targeting was assumed proportional to biomass.
EffYears: Years representing join-points (vertices) of time-varying effort. Vector. Non-negative real numbers
Historical fishing effort for 1966 - 1989 was estimated from the 2011 Assessment.
EffLower: Lower bound on relative effort corresponding to EffYears. Vector. Non-negative real numbers
See above.
EffUpper: Upper bound on relative effort corresponding to EffYears. Vector. Non-negative real numbers
See above.
EffYears | EffLower | EffUpper |
---|---|---|
1966 | 0.636 | 0.636 |
1967 | 1.120 | 1.120 |
1968 | 0.688 | 0.688 |
1969 | 1.000 | 1.000 |
1970 | 1.240 | 1.240 |
1971 | 0.767 | 0.767 |
1972 | 0.522 | 0.522 |
1973 | 0.600 | 0.600 |
1974 | 0.739 | 0.739 |
1975 | 0.612 | 0.612 |
1976 | 0.512 | 0.512 |
1977 | 0.332 | 0.332 |
1978 | 0.300 | 0.300 |
1979 | 0.345 | 0.345 |
1980 | 0.268 | 0.268 |
1981 | 0.437 | 0.437 |
1982 | 0.344 | 0.344 |
1983 | 0.285 | 0.285 |
1984 | 0.314 | 0.314 |
1985 | 0.243 | 0.243 |
1986 | 0.382 | 0.382 |
1987 | 0.464 | 0.464 |
1988 | 0.497 | 0.497 |
1989 | 0.701 | 0.701 |
Esd: Additional inter-annual variability in fishing mortality rate. Uniform distribution lower and upper bounds. Non-negative real numbers
Specified Value(s): 0.1, 0.3
A small amount of variability was added to the estimated effort trend.
Histograms of 48 simulations of inter-annual variability in historical fishing mortality (Esd
), with vertical colored lines indicating 3 randomly drawn values used in the time-series plot:
Time-series plot showing 3 trends in historical fishing mortality (OM@EffUpper
and OM@EffLower
or OM@cpars$Find
):
qinc: Average percentage change in fishing efficiency (applicable only to forward projection and input controls). Uniform distribution lower and upper bounds. Non-negative real numbers
Specified Value(s): 0, 0
No directional change in catchability was assumed for future projections.
qcv: Inter-annual variability in fishing efficiency (applicable only to forward projection and input controls). Uniform distribution lower and upper bounds. Non-negative real numbers
Specified Value(s): 0.05, 0.1
A small degree of inter-annual variability in catchability was assumed.
Histograms of 48 simulations of inter-annual variability in fishing efficiency (qcv
) and average annual change in fishing efficiency (qinc
), with vertical colored lines indicating 3 randomly drawn values used in the time-series plot:
Time-series plot showing 3 trends in future fishing efficiency (catchability):
L5: Shortest length corresponding to 5 percent vulnerability. Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 35, 39
Bracketed around the estimated selectivity from the 2011 assessment.
LFS: Shortest length that is fully vulnerable to fishing. Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 42, 48
Bracketed around the estimated selectivity from the 2011 assessment.
Vmaxlen: The vulnerability of fish at Stock@Linf . Uniform distribution lower and upper bounds. Fraction
Specified Value(s): 1, 1
The stock assessment assumes that selectivity is asymptotic.
isRel: Selectivity parameters in units of size-of-maturity (or absolute eg cm). Single value. Boolean.
Specified Value(s): FALSE
Selectivity parameters are in absolute units.
LR5: Shortest length corresponding ot 5 percent retention. Uniform distribution lower and upper bounds. Non-negative real numbers
Specified Value(s): 0, 0
Retention is assumed equal to selectivity.
LFR: Shortest length that is fully retained. Uniform distribution lower and upper bounds. Non-negative real numbers
Specified Value(s): 0, 0
Retention is assumed equal to selectivity.
Rmaxlen: The retention of fish at Stock@Linf . Uniform distribution lower and upper bounds. Non-negative real numbers
Specified Value(s): 1, 1
Retention is assumed equal to selectivity.
DR: Discard rate - the fraction of caught fish that are discarded. Uniform distribution lower and upper bounds. Fraction
Specified Value(s): 0, 0
No general discarding.
SelYears: (Optional) Years representing join-points (vertices) at which historical selectivity pattern changes. Vector. Positive real numbers
Slot not used.
AbsSelYears: (Optional) Calendar years corresponding with SelYears (eg 1951, rather than 1), used for plotting only. Vector (of same length as SelYears). Positive real numbers
Slot not used.
L5Lower: (Optional) Lower bound of L5 (use ChooseSelect function to set these). Vector. Non-negative real numbers
Slot not used.
L5Upper: (Optional) Upper bound of L5 (use ChooseSelect function to set these). Vector. Non-negative real numbers
Slot not used.
LFSLower: (Optional) Lower bound of LFS (use ChooseSelect function to set these). Vector. Non-negative real numbers
Slot not used.
LFSUpper: (Optional) Upper bound of LFS (use ChooseSelect function to set these). Vector. Non-negative real numbers
Slot not used.
VmaxLower: (Optional) Lower bound of Vmaxlen (use ChooseSelect function to set these). Vector. Fraction
Slot not used.
VmaxUpper: (Optional) Upper bound of Vmaxlen (use ChooseSelect function to set these). Vector. Fraction
Slot not used.
CurrentYr: The current calendar year (final year) of the historical simulations (eg 2011). Single value. Positive integer.
Specified Value(s): 1989
Based on 1989
MPA: (Optional) Matrix specifying spatial closures for historical years.
Slot not used.
The observation model parameters are taken from the Generic_Obs model in DLMtool.
Cobs: Log-normal catch observation error expressed as a coefficient of variation. Uniform distribution lower and upper bounds. Non-negative real numbers
Specified Value(s): 0.1, 0.3
Borrowed from: Generic_Obs
Cbiascv: Log-normal coefficient of variation controlling the sampling of bias in catch observations for each simulation. Uniform distribution lower and upper bounds. Non-negative real numbers
Specified Value(s): 0.1
Borrowed from: Generic_Obs
CAA_nsamp: Number of catch-at-age observation per time step. Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 100, 200
Borrowed from: Generic_Obs
CAA_ESS: Effective sample size (independent age draws) of the multinomial catch-at-age observation error model. Uniform distribution lower and upper bounds. Positive integers
Specified Value(s): 25, 50
Borrowed from: Generic_Obs
CAL_nsamp: Number of catch-at-length observation per time step. Uniform distribution lower and upper bounds. Positive integers
Specified Value(s): 100, 200
Borrowed from: Generic_Obs
CAL_ESS: Effective sample size (independent length draws) of the multinomial catch-at-length observation error model. Uniform distribution lower and upper bounds. Positive integers
Specified Value(s): 25, 50
Borrowed from: Generic_Obs
Iobs: Observation error in the relative abundance indices expressed as a coefficient of variation. Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 0.1, 0.4
Borrowed from: Generic_Obs
Ibiascv: Not Used. Log-normal coefficient of variation controlling error in observations of relative abundance index. Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 0.2
Borrowed from: Generic_Obs
Btobs: Log-normal coefficient of variation controlling error in observations of current stock biomass among years. Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 0.2, 0.5
Borrowed from: Generic_Obs
Btbiascv: Uniform-log bounds for sampling persistent bias in current stock biomass. Uniform-log distribution lower and upper bounds. Positive real numbers
Specified Value(s): 0.33, 3
Borrowed from: Generic_Obs
beta: A parameter controlling hyperstability/hyperdepletion where values below 1 lead to hyperstability (an index that decreases slower than true abundance) and values above 1 lead to hyperdepletion (an index that decreases more rapidly than true abundance). Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 0.5, 2
Borrowed from: Generic_Obs
LenMbiascv: Log-normal coefficient of variation for sampling persistent bias in length at 50 percent maturity. Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 0.1
Borrowed from: Generic_Obs
Mbiascv: Log-normal coefficient of variation for sampling persistent bias in observed natural mortality rate. Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 0.2
Borrowed from: Generic_Obs
Kbiascv: Log-normal coefficient of variation for sampling persistent bias in observed growth parameter K. Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 0.1
Borrowed from: Generic_Obs
t0biascv: Log-normal coefficient of variation for sampling persistent bias in observed t0. Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 0.1
Borrowed from: Generic_Obs
Linfbiascv: Log-normal coefficient of variation for sampling persistent bias in observed maximum length. Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 0.05
Borrowed from: Generic_Obs
LFCbiascv: Log-normal coefficient of variation for sampling persistent bias in observed length at first capture. Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 0.05
Borrowed from: Generic_Obs
LFSbiascv: Log-normal coefficient of variation for sampling persistent bias in length-at-full selection. Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 0.05
Borrowed from: Generic_Obs
FMSYbiascv: Not used. Log-normal coefficient of variation for sampling persistent bias in FMSY. Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 0.2
Borrowed from: Generic_Obs
FMSY_Mbiascv: Log-normal coefficient of variation for sampling persistent bias in FMSY/M. Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 0.2
Borrowed from: Generic_Obs
BMSY_B0biascv: Log-normal coefficient of variation for sampling persistent bias in BMSY relative to unfished. Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 0.2
Borrowed from: Generic_Obs
Irefbiascv: Log-normal coefficient of variation for sampling persistent bias in relative abundance index at BMSY. Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 0.2
Borrowed from: Generic_Obs
Crefbiascv: Log-normal coefficient of variation for sampling persistent bias in MSY. Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 0.2
Borrowed from: Generic_Obs
Brefbiascv: Log-normal coefficient of variation for sampling persistent bias in BMSY. Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 0.5
Borrowed from: Generic_Obs
Dbiascv: Log-normal coefficient of variation for sampling persistent bias in stock depletion. Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 0.5
Borrowed from: Generic_Obs
Dobs: Log-normal coefficient of variation controlling error in observations of stock depletion among years. Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 0.05, 0.1
Borrowed from: Generic_Obs
hbiascv: Log-normal coefficient of variation for sampling persistent bias in steepness. Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 0.2
Borrowed from: Generic_Obs
Recbiascv: Log-normal coefficient of variation for sampling persistent bias in recent recruitment strength. Uniform distribution lower and upper bounds. Positive real numbers
Specified Value(s): 0.1, 0.3
Borrowed from: Generic_Obs
Histograms of 48 simulations of inter-annual variability in catch observations (Csd
) and persistent bias in observed catch (Cbias
), with vertical colored lines indicating 3 randomly drawn values used in other plots:
Histograms of 48 simulations of inter-annual variability in depletion observations (Dobs
) and persistent bias in observed depletion (Dbias
), with vertical colored lines indicating 3 randomly drawn values used in other plots:
Histograms of 48 simulations of inter-annual variability in abundance observations (Btobs
) and persistent bias in observed abundance (Btbias
), with vertical colored lines indicating 3 randomly drawn values used in other plots:
Histograms of 48 simulations of inter-annual variability in index observations (Iobs
) and hyper-stability/depletion in observed index (beta
), with vertical colored lines indicating 3 randomly drawn values used in other plots:
Time-series plot of 3 samples of index observation error:
Plot showing an example true abundance index (blue) with 3 samples of index observation error and the hyper-stability/depletion parameter (beta
):
Histograms of 48 simulations of inter-annual variability in index observations (Recsd
) , with vertical colored lines indicating 3 randomly drawn values used in other plots:
Histograms of 48 simulations of catch-at-age effective sample size (CAA_ESS
) and sample size (CAA_nsamp
) and catch-at-length effective (CAL_ESS
) and actual sample size (CAL_nsamp
) with vertical colored lines indicating 3 randomly drawn values:
Histograms of 48 simulations of bias in observed natural mortality (Mbias
), von Bertalanffy growth function parameters (Linfbias
, Kbias
, and t0bias
), length-at-maturity (lenMbias
), and bias in observed length at first capture (LFCbias
) and first length at full capture (LFSbias
) with vertical colored lines indicating 3 randomly drawn values:
Histograms of 48 simulations of bias in observed FMSY/M (FMSY_Mbias
), BMSY/B0 (BMSY_B0bias
), reference index (Irefbias
), reference abundance (Brefbias
) and reference catch (Crefbias
), with vertical colored lines indicating 3 randomly drawn values:
We assumed that management was implemented perfectly.
TACFrac: Mean fraction of TAC taken. Uniform distribution lower and upper bounds. Positive real number.
Specified Value(s): 1, 1
Borrowed from: Perfect_Imp
TACSD: Log-normal coefficient of variation in the fraction of Total Allowable Catch (TAC) taken. Uniform distribution lower and upper bounds. Non-negative real numbers.
Specified Value(s): 0, 0
Borrowed from: Perfect_Imp
TAEFrac: Mean fraction of TAE taken. Uniform distribution lower and upper bounds. Positive real number.
Specified Value(s): 1, 1
Borrowed from: Perfect_Imp
TAESD: Log-normal coefficient of variation in the fraction of Total Allowable Effort (TAE) taken. Uniform distribution lower and upper bounds. Non-negative real numbers.
Specified Value(s): 0, 0
Borrowed from: Perfect_Imp
SizeLimFrac: The real minimum size that is retained expressed as a fraction of the size. Uniform distribution lower and upper bounds. Positive real number.
Specified Value(s): 1, 1
Borrowed from: Perfect_Imp
SizeLimSD: Log-normal coefficient of variation controlling mismatch between a minimum size limit and the real minimum size retained. Uniform distribution lower and upper bounds. Non-negative real numbers.
Specified Value(s): 0, 0
Borrowed from: Perfect_Imp
Histograms of 48 simulations of inter-annual variability in TAC implementation error (TACSD
) and persistent bias in TAC implementation (TACFrac
), with vertical colored lines indicating 3 randomly drawn values used in other plots:
Histograms of 48 simulations of inter-annual variability in TAE implementation error (TAESD
) and persistent bias in TAC implementation (TAEFrac
), with vertical colored lines indicating 3 randomly drawn values used in other plots:
Histograms of 48 simulations of inter-annual variability in size limit implementation error (SizeLimSD
) and persistent bias in size limit implementation (SizeLimFrac
), with vertical colored lines indicating 3 randomly drawn values used in other plots: