GIS has for long been heralded as an important development tool for aquaculture planning and development , one which is key in dealing with identification of where potential lies, estimating what production can be leveraged with adequate investment and as essential for defining spatial limits and use zones for end users so diminishing potential conflicts of interest between stakeholders.
Over the years, many studies involving a variety of fish and shellfish in freshwater and marine environments around the globe have been undertaken . Such s tudies encompass regions rang ing from Norway to southern Chile, from Saudi Arabia, to Indonesia , over whole continents like South America and Africa. T he databases utilized can be multi-latitudinal over several countries based sometimes on widely differing national datasets . The results of interpolations carried out on available global databases for criteria such as climate and soils usually are of low resolution and hardly find practical use in regional development offices . Occasionally, private enterprises and a quaculture investment groups will invest in GIS-based studies. State development agencies also may require pre-feasibility studies to guide investments . In both cases end results are frequently not published in scientific journals but usually as reports of limited reach and distribution becoming at most 'grey literature'. Such results are often privile ged or 'proprietary' information, and seldom if ever , disclosed . Other studies never become part of a project duly implemented or of a state development strategy for reasons diverse , such as of that of technical nature , economic trends , geopolitics or even plain lack of available financial resources .
The t ools for elaborating a GIS are many, and some are very powerful. However, the raw materials needed, i.e. databases are many times insufficient, ina dequate in format, extent, volume, or quality or plainly inexistent. To confront these possible shortcomings, some limited alternatives exist, but results may be less trustworthy to place important decisions. H ardly the projected GIS software- supported model outcomes have had to seriously face the final 'quality assurance' test, when a sophisticated multicriterial decision algorithm supported by wide consultation . With poor or hard to obtain spatial databases, GIS modelling be seriously hampered or delayed. Availability of databases and their metadata description is hardly ever is mentioned in preliminary contacts with GIS contractors . Thus GIS experts may eventually have to manually digitize maps, some of them outdated and adjust tables found in government reports to support moeling . Such impon derables lead to delayed produc tion of final mapping and analysis beyond a point in time where changes in politics and deadlines of funding sources catch up, mak ing a proper validation process somewhat or totally unfeasible. In other cases aquaculture projects already en route may continue on a disaster course leading to lack of credibility of the activity.