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UBC Theses and Dissertations

Simulation of voyage economics for salmon seine fishing boats in British Columbia Molyneux, William David


It is important to know the likely income to a fishing vessel, so that it can be operated as a profitable concern for its owner. Most work on fishing vessel design optimization has used average catch size and income as the measure of economic performance. Whilst this analysis is adequate when cost minimization is being considered, it is deficient for developing strategies for maximizing income. One analysis method which allows for the observed random variation in fishing operations is system simulation. It is the intention of this thesis to demonstrate that simulation modelling can be developed into a useful analysis tool for predicting fishing vessel operating economics. The same model can then be incorporated into expert system based design techniques. A simulation model for salmon seine fishing in British Columbia was developed which allowed for variation in catch rates with fishing locations, the distance between the locations and constraints on the fishing process. The vessel operational profile used in the simulation was based on a review of previous research, discussions with fishermen and industry representatives as well as previously unpublished data on vessel mobility and fuel consumption for a specific boat. The other data used in the simulation were developed from records of catches, kept by the Department of Fisheries and Oceans. These data were analyzed by each geographic area, to give the distribution of catch per day, income per day, length of voyage and number of trips per year for the four years 1987 to 1990. The model of the voyage economics was developed for three alternative decision rules. These were to always fish one geographic area (Stationary Model), to select the area which had the best performance during the last opening (Forecast Model) and to select the areas at random (Random Model). The simulation was run for each rule and the results were compared to observations derived from the performance of the actual fleet, for one year of observations. It was found that each simulated decision method was reflective of certain parts of the actual fleet. The results of additional simulations gave valuable insights into the most profitable methods of operating salmon seine fishing vessels. It was predicted that the Forecast Model provided an income 37 percent higher than average, based on four years of real catch data. However, a lower than average performance was predicted when the profit at each area was close to the mean value for all the areas in the model. The simulation quantifies the observed reluctance of skippers to change fishing locations. It was predicted that the vessels in the fleet had hold sizes which were between 60 and 100 percent bigger than was required, based on the most probable fishing trip. It was also predicted that the rate or return, based on the catch data and the investment in the boat, was much lower than would be expected for a high risk venture. When two or more boats operated together and pooled the operating expenses and income, the simulations showed that the risk of the income for the voyage being less than the expenses was considerable reduced. The biggest benefit was for two boats to be fishing together. This factor is important when the number of opportunities to fish are small, as observed in the British Columbia Salmon Season.

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