Geospatial Mapping of Fisheries Profile of West Bengal of India through GIS

In the age of information and technological advancements, location-awareness is becoming a key feature in management of natural resources. Geospatial mapping is a location based study and is a part of intelligence GIS which is expected to be useful tool for fisheries scientists, aquatic resource managers and policy planners in developing and planning strategies for fisheries resources of the country. In this context, a study was performed where mapping of fisheries profile of West Bengal was carried out using GIS tool having critical geographic dimensions. For this purpose, at the core of the system fisheries data of West Bengal were accessed and integrated from different sources at district level. Data were tabulated using Microsoft Excel and then joined to digitize Map of West Bengal to enable mapping using Arc info 9.3 GIS software. This was further synchronized and integrated to generate four thematic maps based on different criteria. The map dealing with fisher folk population and their occupation contains the searchable criteria as regards to the fishermen population as well as their classified categories according to their occupation. The map dealing with West Bengal fish production contains fish production, fish seed production district-wise and growth rate for 2004-2008. The third map contains district-wise water resources and reservoir areas along with brackish water. With this mapped information, planners and various stakeholders will have readily accessible district level data on various components of fisheries of West Bengal, thereby facilitating better planning, management and development of the fisheries sector.

An optimal management strategy for stochastic population dynamics of released Plecoglossus altivelis in rivers

Excessive predation pressure from the waterfowl Phalacrocorax carbo(Great Cormorant)on Plecoglossus altivelis(Ayu)has recently been a severe problem of river environment in Japan.Local fishery cooperatives are currently suffering from economic difficulties due to decrease of the fish catch of P.altivelis.Local fishery cooperatives and municipalities have been enthusiastically trying to develop countermeasures that can effectively reduce the predation pressure;however,their effectiveness and efficiency have not been systematically quantified well.This aim can be achieved with the help of an appropriate mathematical model.In this paper,based on a pure death process,a practical stochastic control model for population dynamics of released P.altivelis in river environment under predation pressure from P.carbo,harvesting by human,and environmental fluctuations is proposed.Finding an optimal management strategy ultimately reduces to solving a 2D Hamilton–Jacobi–Bellman equation,which is performed with a finite element scheme.Its application to a Japanese river environment successfully computes the optimal management strategy that is consistent with the reality.Numerical sensitivity analysis of the presented mathematical model is also performed for comprehension of dependence of the optimal strategy on the model parameters.