Hi Abdul, i don't know if this is what you are looking for but NOAA and NASA provide a great variety of global ocean data.

For example NOAA:

https://www.ncei.noaa.gov/products/world-ocean-database

https://coastwatch.noaa.gov/cw_html/cwViewer.html

and NASA:

https://salinity.oceansciences.org/data-maps.htm

https://earthdata.nasa.gov/learn/discipline/ocean

I hope this gives you a few starting points.

Hannes Reinwald has provided a good direction to obtaining initial data. The only way to identify potential fishing areas is to sample on a monthly basis and relate CPUE to the oceanographic variables you collecting eg...SST etc. This is a challenging task as targeted fish prefer different habitats...rocky bottoms, sandy bottoms, etc.

Good luck

https://oceanview.pfeg.noaa.gov

Are you looking at both recreational and commercial fishing? I also suggest CPUE from regular sampling however. You must also consider the target species you are after as different fishing methods will need to be used accordingly as you may end up not getting the fish in your catches due to the wrong fishing method.