Many instrument concepts and techniques have been tried from outer space for ocean research. The main instruments (sensors) that are being used for satellite oceanographic observations are visible, thermal and microwave sensors, viz. Ocean Colour Monitor (OCM), Thermal Infrared Radiometer (TIR), Scatterometer (SCAT), Synthetic Aperture Radar (SAR), Altimeter (ALT), Microwave Radiometers, Imaging Spectrometers and High Resolution Imagers. These instruments provide a wealth of information on a diverse range of geophysical and biological parameters and phenomena, such as surface or near-surface roughness, large-scale surface topography, wind fields, etc. Measurements of these features and their variations over space and time can be interpreted to provide information relating to biological productivity, fish location, currents, sea state, surface winds, water composition and quality, sedimentation patterns, pollution and other phenomena. Integration of complementary data from different instruments is often used, to increase the information content of the data collected. Detailed study of open water phenomena are best done with sensors designed for oceanographic observations, while coastal studies can often be done with remote sensing satellites designed for land applications.
There are a large number of ways in which GIS is presently being utilized to assist in fisheries management or research. Some of these include:
- Distribution displays- this is simply the drawing of maps to show the distribution of any feature or combination of marine and /or fisheries features.
- Marine habitat mapping and analyses-establishing the essential components of habitats is an ideal way to utilize GIS, e.g. perhaps with a view to aquatic conservation designations.
- Resource analyses-to quantify and display the disposition and dynamics of any marine resource or combination of resources.
- Modeling- these functions include work on illustrating themes, often in a simplistic or general way, or there may be predictive modeling to show the outcome of potential decisions or actions.
- Monitoring management policies-i.e. to best sustain fish yields, fishing effort needs to be optimally deployed, perhaps with the help of electronic log-books or vessel monitoring system tracking data.
- Ecosystems relationships- e.g. predator/prey relationships or relationships betwee3n fish distributions and any environmental parameter.
- Marine protected areas-i.e. identifying suitable areas for species protection, or for exclusion of fishing and analyzing the results achieved by these areas.
- Marine spatial planning- i.e. determining marine allocations, such that competing users of the marine space can all best function sustainably. This is complex given the number of often conflicting parties involved plus the variety of spatial considerations.
- The creation of economic surfaces-i.e. allowing researchers to model the likely income derived from fishery products based on alternative management and resource extraction scenarios.
- Ecosystem approach to fisheries- GID is the ideal tool to assist in identifying ecosystems disequilibrium and to predict and depict scenarios for improved management practices.
Conclusion
Remote Sensing and GIS with its inherent advantage of synoptic coverage and receptivity has become an indispensible tool for studying, research, planning operation and management of water bodies including in land, coastal and marine. Fisheries and Aquaculture which are the major industry connected with water bodies is thus benefiting from the technology and has progressed at a good pace. Geospatial technologies, Remote Sensing (RS) and Geographical Information Systems (GIS) have shown great potential to be used successfully in planning various activities of aquaculture like site selection, location of cages for mariculture, utilizing bays for sea weed culture etc. In fact, the geospatial technologies have become increasingly significant for environmental planning and assessment mainly because of the need to generate a number of spatial datasets, couple these spatial data with their attributes and do an overlay analysis. GIS has several other advantages for aquaculture development programs. It not only provides a visual inventory of the physical, biological, and economical characteristics of the environment, it also allows rational management without complex and time-consuming manipulations. Continuous research in the areas of application of geospatial tools in fisheries over the past three decades has made a good progress in its application in the areas of Marine capture fishery, marine culture fishery, coastal aquaculture, inland aquaculture, inland water bodies and management and the continuous improvement in the technology only helps in the sustainable growth of the fisheries industry.