The red circles appear to be used to link to a country's attribute information. The smallest circle represents 0 tons, which you can easily find out by hovering over a red circle in a landlocked country.
Norway has a very long coastline, and do not have many neighbors where they would have to reduce or negotiate their EEZ (200 nm) boundary. They also control those islands to the north, thus extending their EEZ quite a bit.
If you click the Details button at the upper left of the map, the information is there (Miguel Paredes of Esri UK made it).
Smallest circles actually represent the entire class of 0 - 50,939 tons. So some small circels do have values.
This seems like poor symbology to me. With so many locations having zero tons caught there should be a class for zero with a different color cricle (gray?), or no symbol at all if the location simply could not have participated in the marine fish catch anyway.