We did catch them but did not count...
We don't know why, but now it does count...
Found the problem, only for Germans and France.

The "Yellow Swordfish" is always called "Swordfish" (Espadon/Schwertfish) (Fr./Ger.) however if it is the normal or the yellow one.

The quest accepts swordfishes from the Arsha Sea (i.E. near Al-Naha-Island), but no spearfishing from Ross Sea (German game client). There seems to be 2 types of identical named swordfish (id:8227 and id:8324), and only one type (id:8227) accepted by the quest.

There exists no hotspot (blue fish), with the high "trash rate" of other fishes in Arsha Sea the quest is very hard. Perhaps possible with many participants; we gave up after 1 hour with only 6 "right" fishes.