Changes between Version 1 and Version 2 of EwEugModellingEffortDynamics


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Timestamp:
2010-01-31 12:06:50 (9 years ago)
Author:
varunr
Comment:

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  • EwEugModellingEffortDynamics

    v1 v2  
    2323At each time step, a mean income per effort index ''I,,g,t,,'' is calculated as 
    2424 
    25 [[Image(wiki:EwEugIimages:0800003A.png)]] 
     25[[Image(wiki:EwEugImages:0800003A.png)]] 
    2626 
    2727where ''i'' = ecological species or biomass group, ''q'g,i'' is the catchability coefficient (possibly dependent on Bi) for species'' i'' by gear ''g'', and ''P,,g,i,,'' is the market price obtained per biomass of'' i'' by gear g fishers.  Also, mean fleet profit rates ''PR,,g,t,,'',,,,for fishing are calculated thus: 
    2828 
    29 [[Image(wiki:EwEugIimages:0800003B.png)]] 
     29[[Image(wiki:EwEugImages:0800003B.png)]] 
    3030 
    3131where ''c'',,''g'',, is the cost of a unit of fishing effort for gear g (cost and price factors are entered via the [[Definition of fleets.htm|Definition of fleets]] and [[Market price.htm|Market price]] forms). For each time step, the “fast” effort response for the next (monthly) time step is predicted by a sigmoid function of income per effort and current fleet capacity: 
    3232 
    33 [[Image(wiki:EwEugIimages:0800003C.png)]] 
     33[[Image(wiki:EwEugImages:0800003C.png)]] 
    3434 
    3535Here, ''I,,hg,,'' and ''p'' are fleet-specific response parameters. ''I,,hg,,'' is the income level needed for half maximum effort to be deployed and ''p'' is a “heterogeneity” parameter for fishers: high ''p'' values imply all fishers “see” income opportunity similarly, while low p values imply fishers “turn on” their effort over a wide range of mean incomes, as shown in Figure 3.12. 
    3636 
    37 [[Image(wiki:EwEugIimages:0300003D.png)]] 
     37[[Image(wiki:EwEugImages:0300003D.png)]] 
    3838 
    3939'''Figure 3.12''' Effect of the ‘heterogeneity’ parameter, ''p'', on effort/income function. 
     
    4242For each fleet, slow effort responses are modelled as changes in fleet capacity (''K'',,''g,t'',,), which is a function of the capital depreciation rate ''ρ,,g,,'', the capital growth rate ''r'',,''g,t'',,'and profit ''PR'',,''g,t'',,. The capital growth rate is calculated via a growth factor ''gf'',,''g'',,,t, i.e., 
    4343 
    44 [[Image(wiki:EwEugIimages:0800003E.png)]] 
     44[[Image(wiki:EwEugImages:0800003E.png)]] 
    4545 
    4646where ''K'',,''g,1'',,'', ρg'' and ''r'',,''g,1'',, are set by the user. The annual capacity ''K'',,''g,t'',, is then updated as 
    4747 
    48 [[Image(wiki:EwEugIimages:0800003F.png)]]. 
     48[[Image(wiki:EwEugImages:0800003F.png)]].