Changes between Version 1 and Version 2 of EwEugProduction


Ignore:
Timestamp:
2010-01-28 14:39:42 (10 years ago)
Author:
varunr
Comment:

--

Legend:

Unmodified
Added
Removed
Modified
  • EwEugProduction

    v1 v2  
    55Even if the parameter is labelled ‘production/biomass’ in EwE, what should be entered is actually the mortality rate. An example, if you have a juvenile group and use a bioenergetic model to calculate the production, you should subtract the amount that is recruited to the adult group from the production in order to the actual mortality, which is what Ecosim needs to work with. Production over biomass is entered on the [[Basic input.htm|Basic input]] form. See [[Mortality coefficients.htm|Mortality coefficients]] and [[Predation mortality.htm|Predation mortality]] for description of Ecopath’s estimates of different mortality components in the system. 
    66 
    7 === Total mortality catch curves === 
     7'''Total mortality catch curves''' 
    88 
    99Total mortalities can be estimated from catch curves, i.e., from catch composition data, either in terms of age-structured catch curves; (Robson and Chapman, 1961), or of length-converted catch curves (Pauly et al., 1995). The estimation can be carried out using appropriate software for analysis, such as the FiSAT package (Gayanilo et al., 1996). 
    1010 
    11 === Total mortality from sum of components === 
     11'''Total mortality from sum of components''' 
    1212 
    1313Production rate is the sum of natural mortality (''M = M0'' + ''M2'') and fishing mortality (''F''), i.e., ''Z'' = ''M'' + ''F''. In the absence of catch-at-age data from an unexploited population, natural mortality for finfish can be estimated from an empirical relationship (Pauly, 1980) linking ''M'', two parameters of the von Bertalanffy Growth Function (VBGF) and mean environmental temperature, i.e., 
     
    2323where the yield is a rate, (e.g., t/km²/year), the biomass lacks a time dimension, (i.e., is expressed as t/km²), and thus the fishing mortality is an instantaneous rate, (e.g., per year). 
    2424 
    25 === Total mortality from average length === 
     25'''Total mortality from average length''' 
    2626 
    2727Beverton and Holt (1957) showed that total mortality (Z = P/B), in fish population whose individuals grow according to the von Bertalanffy Growth Function (VBGF), can be expressed by: