Growth and distribution of port-based global fishing effort within countries EEZs.

摘要

Analyzing spatio-temporal evolution of global fishing effort provides an insight into mechanisms driving fishing effort temporal and spatial expansions. It also enables contrasting fishing effort spatio-temporal trends against the well-documented fact of overall global depletion of major commercial fish stocks. This thesis presents analysis of the evolution and spatial distribution of port-based global fishing effort from 1970 to 2000. A fishing effort spatial distribution prediction model, involving qualitative filter criteria and quantitative weighting of fishing grounds, is developed to predict the spatial distribution of port-based global fishing effort within the EEZs of countries. Countries of the world were grouped into four regions for regional analysis and then pooled for an overall analysis of global spatio-temporal trends.; The results of the analyses showed that, on global scale, effective fishing effort grew by 600% in the period between 1970 and 2000. This growth led to reduction of total catch per unit of effort (CPUE) by 80% over the same period. The results of the prediction of spatial distribution of port-based global fishing effort showed that the distribution of global fishing effort covered the continental shelves of the world's ocean in the 1990s, with intensely fished areas clustered along the coasts of major fishing nations. On top of offshore range expansion, the results revealed that the centers of massive fish catch and effort concentrations have gradually moved southward by 20° and 10° respectively. Additionally, fuel consumption rate of port-based global fishing fleets was estimated, using an independent estimate of global fisheries fuel consumption. The result gave a fuel consumption rate of 0.1-0.3 liters per horsepower-hour. When this rate is applied to time-series of global fishing fleet, the result showed that the fuel consumption of global fishing fleet grew by 85% between 1970 and 2000.