The Redevelopment On Simulating The Aquatic Animals Migration In Yangtze River Based On MapX

Yangtze River had always been the ideal habitat, breeding ground, and migration channel by aquatic organisms. However, severely impacted by intensive human activities, species resources in Yangtze River have been on constant decline, and the situation of migration species is among the worst. Species in Yangtze River are deprived of the opportunities of the survival of the fittest. As the result, idioplasmic quality becomes increasingly degraded. Nowadays, Coilia ectenes, Coilia mystus, Anguilla japonica and Eriocheir sinensis H.milne-edards are the only four migratory fish species traveling between Yangtze River and sea, on which we still have fishing season, but even their resources are becoming rare. This is mainly due to the fact that these migration species have to be confined within limited space instead of for migration species in contrast to desirable space of thousands of miles. The problem is mainly caused by the river-lake isolation and the environmental pollution. By taking into account migratory cycle, migratory route, migratory time and geographic distribution, we developed "Geographic Information System (GIS) for Migration Fishery Resources in the Yangtze River Mainstream". In addition, based on the characteristic of these migratory fish species, we conducted research on the methods expressing migratory time, migratory space and related attribute data synchronically, so that other scholars and managers can get some insights from the simulation of migration.Based on the characteristics of the change over the aquatic animal migration in Yangtze River between different years and demands from different user groups, we used Microsoft Visual Basic 6.0 as the platform for system development and Microsoft Access 2003 as the management tool for back-end attribute database. Based on MapX, we developed "GIS for Migration Fishery Resources in the Yangtze River Mainstream". With ADO and DAO as database access interface, this system makes the connection between attribute data and spatial data, and the updating of database information come true. In addition to that, this system establishes a series of layers which is compatible with MapInfo, such as Yangtze valley map, islands location map, migratory route, and monitor stations.After going through the stages of the requirement specification, data compilation, system designing, developing and debugging, now "GIS for Migration Fishery Resources in the Yangtze Rive Mainstream" takes an early shape. Not only does this system have functionalities from average commercial GIS software, e.g. file management, view processing, feature query and input, layers management, theme mapping, map output and printing, but also the database update, intelligent distinction and vector representation of the distribution function and quantity of migratory fish. In addition to that, by leveraging the programming function of MapX, we have made breakthrough on various technical bottlenecks, which includes features instantaneous smooth moving and refreshing. Thanks to those breakthroughs, dynamic simulation of migration species, their distribution, migration and change tendency are made possible and actually implemented. In addition, the system offers more extensibility by providing the functionalities of attribute data and spatial data management. It can also facilitates government's decision making through system analysis, and serves as an ideal supporting platform for efficient and sustainable usage of data fishery resources.In this research, we started by introducing the situation of migration species resources in Yangtze River in a overall perspective, both the history and the status quo of the Geographic Information System for marine fishery and inland-water fishery. Then, we describe the requirement specification and the methodology for "GIS for Migration Fishery Resources in the Yangtze River Mainstream", especially the two innovative functions of the system, which are the demonstration of changing distribution of migratory fish, and the dynamic simulation of migration process. The source code of the core functionalities is also presented. Moreover, to demonstrate the application of the system, we apply it to the data from investigation which was hold in 2004 for matured mitten crab resource in the estuary of the Yangtze River. During the application process, we discussed some technical challenges we faced and tackled during the development. Last, we explore the prospect for the usage of three-dimensional spatial data, the integration of GPS and GIS technologies, and the use of Web GIS for fishery. At the same time, we identified various shortcomings in developing the system, and gave some potential suggestions.