HyperNews for Harvest Modeling Project
22 August 1997 Meeting Minutes
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Forum:
Discussion of Harvest Modeling Project
Date: Mon, 08 Sep 1997 20:00:16 GMT
From: Admin
robert.kope@noaa.gov 206-860-3374
Jim Scott (NMFS) james.b.scott@noaa.gov 360-783-5827
Ken Newman (UI) newman@uidaho.edu 208-885-6861
Jim Norris (UW) jnorris@olympus.net 360-385-4486
Dell Simmons (USFWS) dell_simmons@mail.fws.gov 260-695-7605
Jennifer Gutmann (UWIFC) jgutmann@nwifc.wa.gov 360-438-1180
Din Chen (CDFO) chend@pbs.dfo.ca 250-756-7341
Cara Campbell (NMFS) cara.campbell@noaa.gov 206-860-6780
Jim Anderson (UW) jim@fish.washington.edu 206-543-4772
Christine Muongchanh (UW) cket@fish.washington.edu 206-543-7848
Carrie Cook-Tabor (USFWS) cooktckc@dfw.wa.gov 360-902-2838
Norma Jean Sands (ADFG) normas@fishgame.state.ak.us 907-465-4254
Gary Morishima (QINC) morikog@aol.com 206-236-1406
David Caccia (UW) davec@oak.cbr.washington.edu
Peter Lawson and Tom Wainwright joined the meeting via speaker phone from
Newport, OR.
2. Update on code development (Jim Norris):
Jim Norris began by describing the fundamental parameter specification
dilemma: How to maintain complete parameter specification flexibility
without restricting the process equations? For example, most existing
models assume the natural mortality rate is age specific, but is constant
for all years and stocks. In this case, the parameter is specified by a
single age index--NatMortRt(age). It is conceivable that future models also
may want the natural mortality rate to vary by year, time step, region, and
cohort. To get this type of flexibility would require a five dimensional
array -- NatMortRt(age,year,step,region,cohort). It is probably impossible to
have arrays this big, so some sort of variable array specifications will be
required.
Jim gave a summary of the potential specification levels for different
processes:
Non-salmon processes (e.g., physical environment and non-salmon biological
environments) may have parameters that vary by:
-- year
-- time step
-- region
Salmon processes (e.g., natural mortality, growth, spawning, migration) may
have parameters that vary by:
-- year
-- time step
-- region
-- cohort
Fishing processes (e.g., legal and incidental fishing mortalities) may have
parameters that vary by:
-- year
-- time step
-- region
-- cohort
-- fishery
To fully specify all parameters with maximum flexibility using a
traditional multidimensional array approach would require a huge number of
parameters. Jim distributed a summary of a Generic Parameter System that
Troy developed that allows complete flexibility in specifying parameters (a
copy of the description is available at
/harvest/gen_param.html). The goal of the
system is to provide sparse arrays of arbitrary dimension and size at run
time, without requiring changes in the underlying source code.
The primary component of the system is a GenericParamArray object that
holds pointers to either another GenericParamArray or a GenericParamFinal
value. This provides for the arbitrary number of dimensions for each
parameter.
One requirement of this system is to have some dimensions specified at the
model level:
-- Number of geographic areas
-- Number of species
-- Number of stocks for each species
-- Number of age classes for each species
The following dimensions can be specified at the year level:
-- Number of time steps for each year
-- Number of cohorts for each stock for each year
-- Number of fisheries for each year
Jim Scott questioned why the number age classes was under the model level,
and not the stock level. Jim explained it was necessary to specify the
number of age classes at the highest possible level to make the
GenericParamArrays work properly. Stocks that typically had fewer age
classes (e.g, 4 instead of 6) would simply have zero abundance in the
higher age classes. For example, the migration matrices for those stocks
would migrate all the age 4 fish into the spawning grounds.
Gary noted that the number of years was missing from the model level. Jim
agreed.
Carrie pointed out that fixing the number of geographical areas at the
model level could cause a problem because the Proportional Migration (PM)
model sometimes has different areas in different years and time steps. She
noted that the PM model uses CWT recoveries from statistical areas to
determine the "donor" areas, and these can change from time step to time
step. Jim N suggested that this may not be a problem if the areas are
specified at the highest possible resolution in the model, and then
defining migration matrices in terms of groups of areas. Jim N said he
would discuss this issue with Troy.
Gary noted that the generic system is to set up pointers to different
parameters. He also questioned about the data types and was concerned that
small typos could mess up the configuration. He stressed the need to make
sure that pointers point to the right location. Jim Norris will pass on
this concern to Troy.
Robert commented that this configuration will allow us to set up separate
data types. The configuration file will be set up without having to access
the source code.
Jim Norris added that the Generic Parameter System was not implemented yet
and might not be the final model.
Jim Scott encouraged that we try this configuration to see how it works.
There was general concern about the added access time the generic system
might require. Jim said he and Troy had discussed this and had concluded it
would not be significantly slower. The group recommended that the system be
tested against a full array system. Jim agreed to do the test.
3. Update on migration algorithm report (Jim Norris):
Jim Norris stated that many people had trouble with the migration matrix
notation in the State Space Model (SSM). Currently, the rows index the "to"
regions and the columns index the "from" regions. Thus, each element of the
matrix, say a(i,j), represents the fraction moving from region j to region
i. Most people would like each element to represent the fraction moving
from region i to region j. Jim asked if anyone would object to changing the
definition of the matrix. This would result in the SSM formula using the
transpose of the matrix. No strong objections were voiced.
Jim asked if anyone had come up with a better intuitive definition for the
migration matrix elements when applied to the Proportional Migration model.
No one had given this any thought.
Jim would like to add the "Box Car" model to the report. Robert thought it
was a good idea and agreed to give Jim some references on it.
4. Report on FRAM development for 1998 season (Carrie Cook-Tabor, Jennifer
Gutmann).
Jennifer briefly reported on the July 15 meeting on FRAM development. Jim
Packer is doing most of the coding to allow the FRAM model to evaluate
selective fisheries. This modification is required by the letter of
agreement between the Tribes and Washington Department of Fish and Wildlife
regarding mass marking. Minutes of the July 15 meeting were distributed
(these are available at /harvest/fram.html).
Basically, the FRAM model is being modified to double the number of stocks,
thus allowing each stock to have marked and unmarked components.
Gary asked how the new FRAM model would be evaluated and tested. He
suggested using the same datasets used by the PSC Selective Fishery Model a
few years ago to see how different the results are from the two models. It
was left uncertain who, when, or how the new FRAM model would be tested.
5. Update on State Space Model development, parameter estimates, and
utilization (Ken Newman).
Ken began by outlining general project objectives:
-- Protection/Adequate Escapements
-- Set Catches
-- Season "stability"
Management actions to meet these objectives include time/area closures,
quotas, ceilings, selective fisheries, etc.
Tools for evaluating the actions must have the following characteristics:
-- Reflective of actions
-- Structurally meaningful (causal, biological)
-- Must reflect uncertainties
Ken showed some examples of how the State Space Model (SSM) can be used. He
showed results of Monte Carlo simulations (box plots of total catches from
100 games). The sources of variation in these simulations were: annual and
stock to stock variation in SSM parameters (i.e., initial survival, initial
distribution, catchability coefficients, migration parameters) or whatever
the deviation is between what is said will be done management-wise and what
actually occurs.
There are 5 specific parameter estimates from the current version of the SSM:
1. Initial survival rate
2. Initial location (location parameter of a beta distribution; the shape
parameter is fixed at 2.0)
3. US Fishing Effectiveness
4. Canadian Fishing Effectiveness
5. Movement parameter (location parameter of a beta distribution; the shape
parameter is fixed at 3.0)
The natural mortality parameter is set to zero during the time steps of the
fishing period.
The latest results show a more consistent pattern for the fishing
effectiveness estimates (i.e., the US and Canadian values are in the same
relative position from year to year). The previous results were inconsistent.
Ken has found that the estimated migration rates range from 0 to 86 km/day,
but are generally within observed values.
Ken described his latest work using both an inner model and an outer, or
hypermodel. There are 5 parameters in the inner or SSM. These are generated
from a multivariate hyperdistribution, a so-called "outer" model. This is
currently formulated as simply the joint distribution of 5 independent
random variables. Four of the distributions are gamma(alpha[i], beta[i])
i=1,..,4 and one is beta(alpha,beta). The parameters of this
hyperdistribution are called hyperparameters, of which there are 10. Five
of the hyperparameters are fixed and 5 are estimated from historical data.
Ken noted that his biggest headache now is getting data. Specifically, for
a given year and a given stock he needs two tables (matrices) of data. The
first has areas for rows, statistical weeks for columns, and all CWT
recoveries (by gear type if possible) for each element. The second matrix
has the same row and column indices, but has some consistent measure of
effort for each element.
Ken asked for comments on whether his model system has anything missing
(leakage).
For future work, Ken suggested the following:
-- Use non-normal, non-linear SSM (e.g., log-normal, Poisson)
-- More complex spatial framework (e.g., ocean and Puget Sound migration path)
-- More complex fisheries interaction (e.g., competing gear types and
different temporal scales)
-- Partitioning sources of variation (i.e., isolate and quantify each of
the sources of variation, trying to determine the more serious or
influential sources. Potentially, perhaps, data collection methods might be
changed.
The meeting was adjourned at 12:30 pm. Next meeting was scheduled for
Tuesday, October 28 at NMFS Montlake Lab.
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