B_{0} 
is the virgin biomass (often expressed in terms of the biomass
of mature females)  see also K. 
B_{MSY} 
is the biomass at which MSY is achieved. 
B_{t} 
is the (exploitable) biomass at the start of year
t. 

is the catch by all geartypes during year t. 

is the catch by geartype g during year
t. 
Depletion 
is the ratio of the biomass in a given year to that in a
virgin state. 

is the fishing mortality at which the slope of the
yieldperrecruit curve is 0.1 of that at the origin. 

is the ith hypothesis (the combination of a model and a
set of values for its parameters). For cases in which the model is assumed
known, corresponds solely to a set of
values for the model parameters. 

is the index of abundance for year t. 
K 
is the environmental carrying capacity  see also
B_{0}. 

is the likelihood of the data given a parameter vector (see
Section 1.3.1). 

is the instantaneous rate of natural mortality. 
MCMC 
Markov Chain Monte Carlo  a numerical method for computing
posterior distributions. 
MSY 
is the Maximum Sustainable Yield. 
MSYR 
is the ratio of MSY to
B_{MSY}. 

is the number of fish of age a and sex s at the
start of year t. 
N(x,y^{2}) 
is the normal distribution with mean x and standard
deviation y. 

is the recruitment (
is the recruitment during year t). 

is the recruitment in a virgin state. 

is the average recruitment. 

is the spawner stock size
( is the spawner stock size at the
start of year t). 
SIR 
SampleImportanceResample  a numerical method for computing
posterior distributions. 
Steepness 
is the ratio of the recruitment expected at 20% of
B_{0} to the recruitment expected at B_{0} (see
also h). 
U[a,b] 
is the uniform distribution on the range a to
b. 

is the value of some function f of the model
parameters. For example, f could simply involve selecting one of the
parameters or some more complicated function such as projecting the model and
computing the current biomass. 

is the product of the likelihood function and the prior
evaluated at the parameter vector
. 
h 
is the steepness of the stockrecruitment relationship (the
ratio of the expected recruitment at 20% of B_{0} to the expected
recruitment at B_{0}). 
k 
is a (constant) harvest rate. 

is the prior probability of the parameter vector
. 
q 
is the catchability coefficient  the parameter which relates
catch rate to exploitable biomass. 

is the intrinsic growth rate parameter for a biomass dynamics
model. 
s 
is the annual survival rate. 

is the relative selectivity of the gear used by geartype
g on fish of age a and sex s during year
t. 

is the exploitation rate on fish of age a and sex
s by geartype g during year t. 

is the weight of a fish of age a and sex s
during year t. 

is the slope of the stockrecruitment relationship at the
origin (or the logarithm of this slope). 

is the parameter that determines the carrying capacity for a
stockrecruitment relationship. 

is a multiplicative factor to adjust the output of the
stockrecruitment relationship for year t. 
l 
is the intrinsic growth rate parameter (also referred to as
r). 

is the vector of model parameters;
is the jth element of
. 

is the posterior probability of the parameter vector
. 

is the importance function. 

is the amount of temporal autocorrelation in assessment
error. 

is the amount of temporal autocorrelation in process
error. 

is the standard deviation of the extent of assessment
error. 

is the standard deviation of the extent of implementation
error. 

is the standard deviation of the process error. 

is the standard deviation of the interannual variation in
catchability. 

is the standard deviation of the noise about the
stockrecruitment relationship. 

is the standard deviation of the variation in biomass due to
environmental fluctuations. 

is relative fecundity as a function of age. 