Changes between Version 3 and Version 4 of EwEugModellingEffortDynamics


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Timestamp:
2010-11-22 01:11:39 (9 years ago)
Author:
shermanl
Comment:

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  • EwEugModellingEffortDynamics

    v3 v4  
    66 2. By entering annual patterns via reference csv files along with historical ecological response data; and 
    77 
    8  3. By treating dynamics of fleet sizes and resulting fishing effort as unregulated and subject to fisher investment and operating decisions (“bionomic” dynamics, fishers as dynamic predators). 
     8 3. By treating dynamics of fleet sizes and resulting fishing effort as unregulated and subject to fisher investment and operating decisions ("bionomic" dynamics, fishers as dynamic predators). 
    99 
    10 To facilitate exploration of alternative harvest regulation policies, the Ecosim default options are (1) or (2).  However, users can invoke the fleet/effort dynamics model by checking the box on the [[Ecosim parameters.htm|Ecosim parameters]] form. Input parameters must be set on the [[Fleet size dynamics.htm|Fleet size dynamics]] form. 
     10To facilitate exploration of alternative harvest regulation policies, the Ecosim default options are (1) or (2).  However, users can invoke the fleet/effort dynamics model by checking the box on the [EwEugEcosimParameters Ecosim parameters] form. Input parameters must be set on the [EwEugFleetSizeDynamics Fleet size dynamics] form. 
    1111 
    12 When the fleet/effort response option is invoked, using the checkbox on the Ecosim [[Run ecosim.htm|Run Ecosim]] form, Ecosim erases all previously entered time patterns for fishing efforts and fishing rates, and replaces these with simulated values generated as each simulation proceeds. The fleet/effort dynamics simulation model uses the idea that there are two time scales of fisher response: 
     12When the fleet/effort response option is invoked, using the checkbox on the Ecosim [EwEugRunEcosim Run Ecosim] form, Ecosim erases all previously entered time patterns for fishing efforts and fishing rates, and replaces these with simulated values generated as each simulation proceeds. The fleet/effort dynamics simulation model uses the idea that there are two time scales of fisher response: 
    1313 
    14141) A short time response of fishing effort to potential income from fishing, within the constraints imposed by current fleet size, and 
    1515 
    16 2) A longer time investment/depreciation ‘population dynamics’ for capital capacity to fish (fleet size, vessel characteristics). 
     162) A longer time investment/depreciation 'population dynamics' for capital capacity to fish (fleet size, vessel characteristics). 
    1717 
    18 These response scales are represented in Ecosim by two ‘state variables’ for each gear type ''g''. 
     18These response scales are represented in Ecosim by two 'state variables' for each gear type ''g''. 
    1919 
    2020'''Fast time response model''' 
     
    2626[[Image(wiki:EwEugImages:0800003A.png)]] 
    2727 
    28 where ''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: 
     28where ''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: 
    2929 
    3030[[Image(wiki:EwEugImages:0800003B.png)]] 
    3131 
    32 where ''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: 
     32where ''c'',,''g'',, is the cost of a unit of fishing effort for gear g (cost and price factors are entered via the [EwEughDefinitionOfFleets Definition of fleets] and [EwEugOffVesselPrice 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: 
    3333 
    3434[[Image(wiki:EwEugImages:0800003C.png)]] 
    3535 
    36 Here, ''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. 
     36Here, ''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. 
    3737 
    3838[[Image(wiki:EwEugImages:0300003D.png)]] 
    3939 
    40 '''Figure 3.12''' Effect of the ‘heterogeneity’ parameter, ''p'', on effort/income function. 
     40'''Figure 3.12''' Effect of the 'heterogeneity' parameter, ''p'', on effort/income function. 
    4141 
    4242'''Slow time reponse model'''