Commit fa7ffd45 authored by pfreon's avatar pfreon
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Clarification of the .HLP and MODELxx.TXT files regarding the beginning and end of V influence

Explanations on the answer to the questions on the beginning and end of V influence when it occurs before spawing.
parent 3e87ea80
Age at the beginning of environmental influence (expressed in number of past year-classes, being them seasonal or annual)?
Please select the appropriate age at which the influence of environment begins.
Enter 0 if the influence begins before spawning, i.e., during gonad maturation.
If the influence begins before spawning, i.e., during gonad maturation
through an influence on the fecundity or the quality of the gamets, there are
three possible answers. If sexual maturation and spawning occur during the same year
(or season if you are using a seasonal step) answer 1 here and also 1 to the question
"Age at the end of the environmental influence?"). If the sexual maturation occurs
mainly the year or season prior to spawning, answer 0 here and also 0 to the next
question. When it occurs during both years or season, answer 0 and 1.
If there is a single year-class per 12-month intervals, the age 1 limits are
the spawning date (or birth date) and the first birthday, one
year later. Age 2 limits are the first and the secondbirthday, etc.
the spawning date (or birth date) and the first birthday, one year later.
Age 2 limits are the first and the secondbirthday, etc.
If there is are several year-classes per 12-month intervals, the age 1 limits
are the spawning date (or birth date) of a given year-class and the spawning
If there is are several seasonal year-classes per 12-month intervals, the age 1
limits are the spawning date (or birth date) of a given year-class and the spawning
date of the next year-class a few months later, a laps of time which corresponds
to the time intervals of your dataset. Age 2 limits are one and two time intervals,
etc.
......
......@@ -12,5 +12,5 @@ to the time intervals of your dataset. Age 2 limits are one and two time interva
etc.
If the total duration of environmental influence is lower than or equal to one time
interval , enter the same number that you entered to answer the previous question,
interval, enter the same number that you entered to answer the previous question,
relative to the age at the beginning of environmental influence. 
\ No newline at end of file
......@@ -5,10 +5,11 @@ linear model (Graham-Schaefer model) between the CPUE and the fishing
effort E, and on the other hand a power relationship between the CPUE
and the environmental variable V. This latter variable is supposed to
influence both the catchability coefficient and the abundance of
the stock (surplus production). Because the same model with a linear
relationship between the CPUE and V (instead of power one) would result
in an overparameterized model, this model can be also used as a proxy
for this case due to the flexibility of the power relationship.
the stock (surplus production) through a power relationship. Because
the same model with a linear relationship between the CPUE and V (instead
of power one) would result in an overparameterized model, this model can
be also used as a proxy for this case due to the flexibility of the power
relationship.
Please note that theoretically such an equation can be used even when
the influences of the environment on abundance and catchability have
......@@ -19,7 +20,11 @@ In case of identical signs of environmental influences, the most
favorable cases are obtained when the weighting factors are the
same for environmental influence on abundance and on catchability.
This condition is fulfiled when the environmental influence on
abundance concerns all the exploited year-classes.
abundance concerns all the exploited year-classes. In such cases with n
exploited year classes and a recruitment at age tr, the answers given
to the questions "Age at the beginning of environmental influence?"
and "Age at the end of environmental influence?" must be tr and tr+n-1
respectively.
After fitting the model, if the coefficient b is not significantly
different from zero, this suggests that the influence of V could be
......
......@@ -7,8 +7,17 @@ and the environmental variable V when it influences the abundance
and a power relationship between the CPUE and V when it influences
the catchability coefficient.
This kind of non-monotonic equation is useful when the relationship between
CPUE and V is dome-shaped (optimal central value). The graph MSY versus V must
The most favorable cases for using this model are obtained when the
weighting factors of V are the same for environmental influence on
abundance and on catchability. This condition is fulfiled when the
environmental influence on abundance concerns all the exploited
year-classes.In such cases with n exploited year classes and a recruitment
at age tr, the answers given to the questions "Age at the beginning of
environmental influence?" and "Age at the end of environmental influence?"
must be tr and tr+n-1 respectively.
The quadratic equation is useful when the relationship between the abundance
and V is dome-shaped (optimal central value). The graph MSY versus V must
OBVIOUSLY be parabolic. If not, the data-set does not justify such a model
and it is recommanded to the following model belonging to the same family:
......
......@@ -3,9 +3,9 @@ MODEL #34 CPUE = a V^b exp(c V^d E)
This is a surplus production model combining on the one hand the exponential
model (Fox model) between the CPUE and the fishing effort E, and on
the other hand a power relationship between the CPUE and the environmental
variable V. This latter variable is supposed to influence both the
catchability coefficient and the abundance of the stock (surplus
production). Because the same model with a linear relationship between
variable V. This latter variable is supposed to influence both the catchability
coefficient and the abundance of the stock (surplus production) through a power
relationship. Because the same model with a linear relationship between
the CPUE and V (instead of power one) would result in an overparameterized
model, this model can be also used as a proxy for this case due to the
flexibility of the power relationship.
......@@ -19,7 +19,12 @@ version of CLIMPROD. In case of identical signs of environmental
influences, the most favorable cases are obtained when the weighting
factors are the same for environmental influence on abundance and on
catchability. This condition is fulfiled when the environmental influence
on abundance concerns all the exploited year-classes.
on abundance concerns all the exploited year-classes. In such cases with n
exploited year classes and a recruitment at age tr, the answers given
to the questions "Age at the beginning of environmental influence?"
and "Age at the end of environmental influence?" must be tr and tr+n-1
respectively.
If, after fitting the model, the coefficients b and d have opposite
signs, this may correspond to two different cases:
......
......@@ -7,7 +7,16 @@ environmental variable V when it influences the abundance, and a power
relationship between the CPUE and V when it influences the catchability
coefficient.
This kind of non-monotonic equation is useful when the relationship between
The most favorable cases for using this model are obtained when the
weighting factors of V are the same for environmental influence on
abundance and on catchability. This condition is fulfiled when the
environmental influence on abundance concerns all the exploited
year-classes.In such cases with n exploited year classes and a recruitment
at age tr, the answers given to the questions "Age at the beginning of
environmental influence?" and "Age at the end of environmental influence?"
must be tr and tr+n-1 respectively.
The quadratic equation is useful when the relationship between
the abundance and V is dome-shaped (optimal central value). The graph MSY
versus V must OBVIOUSLY be parabolic. If not, the data-set does not justify
such a model and it is recommanded to use the following model belonging to the
......
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