# 7. GLOSSARY

 B0 is the virgin biomass (often expressed in terms of the biomass of mature females) - see also K. BMSY is the biomass at which MSY is achieved. Bt is the (exploitable) biomass at the start of year t. is the catch by all gear-types during year t. is the catch by gear-type 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 yield-per-recruit 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 B0. 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 BMSY. is the number of fish of age a and sex s at the start of year t. N(x,y2) 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 Sample-Importance-Resample - a numerical method for computing posterior distributions. Steepness is the ratio of the recruitment expected at 20% of B0 to the recruitment expected at B0 (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 stock-recruitment relationship (the ratio of the expected recruitment at 20% of B0 to the expected recruitment at B0). 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 gear-type 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 gear-type g during year t. is the weight of a fish of age a and sex s during year t. is the slope of the stock-recruitment relationship at the origin (or the logarithm of this slope). is the parameter that determines the carrying capacity for a stock-recruitment relationship. is a multiplicative factor to adjust the output of the stock-recruitment 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 inter-annual variation in catchability. is the standard deviation of the noise about the stock-recruitment relationship. is the standard deviation of the variation in biomass due to environmental fluctuations. is relative fecundity as a function of age.