Compilation of maps for fishery distribution

Criteria and procedures

For the compilation of maps for fishery distribution, a new approach has undertaken in order to better represent the real distribution of each species. The main source of information to describe the species distribution was their habitat descriptions and geographic distributions as derived from the official FAO Catalogues of Species. It was possible to make use of these information using a modern GIS approach after standardization of all terminology used in the descriptive contexts which is briefly explained hereafter.

In sequence, these are the basic steps that were undertaken: for those species which show some type of relationship with the ocean bottom, habitat's description has been translated in a sequence of depth ranges, using the limits indicates in the Table 1. Once finalized, depth ranges were extracted from a single data set, i.e., the GEBCO Digital Atlas (Natural Environment Research Council. 1994. Digital version of the IOC/IHO General Bathymetric Chart of the Oceans) and transferred to a GIS. Then, information from geographic distribution, i.e., localities and or oceanographic provinces, were extracted from the WVS (World Vector Shoreline at scale 1:43.000.000) and ArcWorld (distributed by ESRI (Environmental Systems Research Institute), 380 New York St., Redlands, California, 92373-8100, USA) and overlaid with former information to produce the final output.

For species with oceanic behaviour, the main source of information derived from direct knowledge and combination of different FAO sources of information. Such amount of data transferred on hand drawn maps, were directly digitized and georeferenced using once again WVS data set and DCW for the exact location of localities and oceanic provinces.

On the final outputs, two different distributions were identified, one where species has been certainly checked and one were spotted or uncertain distribution was provided.

Prepared by:
Fabio Carocci, FAO-FIRM, 2001