Changes between Version 3 and Version 4 of EwEugPredictingSpatialFishingPatterns
 Timestamp:
 20101122 22:40:48 (10 years ago)
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EwEugPredictingSpatialFishingPatterns
v3 v4 1 1 == 4.5 Predicting spatial fishing patterns == 2 2 3 EwE works with multiple fishing fleets, with fishing mortality rates (''F'') initially distributed between fleets based on the distribution in the underlying Ecopath base model. In Ecospace the ''F' ''s are distributed using a simple 'gravity model' where the proportion of the total effort allocated to each cell is assumed proportional to the sum over groups of the product of the biomass, the catchability, and the profitability of fishing the target groups (Caddy, 1975; Hilborn and Walters, 1987). This profitability of fishing includes factors such as the cellspecific cost of fishing.3 EwE works with multiple fishing fleets, with fishing mortality rates (''F'') initially distributed between fleets based on the distribution in the underlying Ecopath base model. In Ecospace the ''F' ''s are distributed using a simple 'gravity model' where the proportion of the total effort allocated to each cell is assumed proportional to the sum over groups of the product of the biomass, the catchability, and the profitability of fishing the target groups (Caddy, 1975; Hilborn and Walters, 1987). This profitability of fishing includes factors such as the cellspecific cost of fishing. 4 4 5 5 Assuming that there are ''N'' cells representing water areas, each fleet k can cause a total fishing mortality rate ''N · F,,k,,''. For each step in the simulation this rate is distributed among cells, c, in proportion to the weights ''G,,kc,,'' based on: